Connections - Winter 2020-21

THE MAGAZINE FOR NICEIC AND ELECSA REGISTERED CONTRACTORS WINTER 2020-21 | ISSUE 216 | £5.00

Light relief How the right lighting can boost remote workers’ mental health

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WINTER 2020-21 | ISSUE 216

24

CASE STUDY 20 David Adams discovers the vital electrical work that went into the NHS’s new Blood and Transplant Centre in Barnsley

HOME OFFICES 24 The effect of light on mood is a tangible one, and with more and more people working from home, many will want to reconsider their home office lighting

VAN/TOOL THEFT 28 Losing your tools to van thieves is a devastating blow for an electrical contractor – here’s how you can make life more difficult for the would-be robbers

CONTRACTOR PROFILE 30 How Wisbech Electrical is

“We know that light can have dramatic effects on the body and mind”

transitioning into a new era under fresh ownership, and flourishing despite the Covid-19 pandemic

TECHNICAL 34 Ask the experts 36 How to identify current system

28

earthing arrangement 42 Apprentice Corner 46 Factors affecting currentcarrying capacity of live conductors 52 Intro to EESS Part 1 59 Protective equipotential bonding

20

TRAINING 1 2 Neil Vincent on how the Covid-19

CURRENT AFFAIRS 66 Appreciation of tradespeople

this challenging period

pandemic has sparked the development of online training

rises as home DIYers find their own skills lacking; furry friends help people cope with the pandemic – and your pictures of pets on the job

INDUSTRY UPDATE 6 WIRE webinars provide pandemic

CAUGHT ON CAMERA 1 5 The worst offenders our contractors

CPD; Watt’s the Matter? campaign

have seen this quarter - including the reckless use of a curtain pole...

HELLO 4 We must stay positive during

7 Government green plan boost; remembering Tony Cable COVER: ISTOCK

PRODUCT FOCUS 64 The latest products on the market

30

8 Proposed bill to tackle dangerous

ADVICE 1 7 Jonathan Amponsah gives his tips for ensuring clients pay up on time

counterfeit electrical goods

10 Consultations on electrician

OPINION 1 8 Single-piece connectors make light work

regulation and rental safety checks

of installing data networks, says Brett Smyth

With developments around Covid-19 moving at a rapid pace, all information in this issue is correct as of Friday 15 January. Due to our printing and distribution processes, it has not been possible to factor in developments since that date. Many thanks for your understanding.

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hello

KEVA T E C HN N I PA CAL RKER

Pulling together Another lockdown was not how we wanted to start 2021 but we must stay positive, in the hope that better times may be around the corner

W

e have entered the 21st year of the 21st century with a mixture of dismay and hope. Like many of you, I was keen to put 2020 to bed and move on from what was a challenging year. However, 2021 started where 2020 left off, as we were faced with another lockdown.

Serious challenges remain, but we must stay positive, work together, keep each other safe and show one another kindness. All being well, the rollout of the vaccine will bring a semblance of normality to our lives sooner rather than later.

What is not clear is how this pandemic will impact us mentally and economically. While the economic impact is largely out of our control, we can improve the wellbeing of our minds and the minds of those around us.

It is well understood that the seasons can impact mental health, and many suffer from the ‘winter blues’. Less commonly known is the role effective lighting can play in improving low mood

– and we have an article on how contractors can help home workers with this on page 24.

The home improvement market presents a real opportunity for us to collectively ensure lighting is a key consideration, and to this end NICEIC and ELECSA have embarked on a national PR campaign called ‘Watt’s the Matter?’

The campaign, which targets consumers through national and regional media, highlights the issue and promotes the use of NICEIC and ELECSA contractors for all electrical installation works.

Before I leave you to enjoy the rest of the issue, I would like to pay a personal tribute to a much admired former colleague and industry champion, Tony Cable, who we lost in November 2020. Tony was a great ambassador for the NICEIC and ELECSA brands and his passing is a loss felt by us and the entire industry.

That’s all from me for now. Until next time, please continue to take every step possible to keep yourself and those around you safe.

‘There is a real opportunity for us to collectively ensure lighting is a key consideration’

Kevan Parker is managing director of Certsure

CO N TAC TS / CO NNE C T IO NS

Level 5, 78 Chamber Street, London E1 8BL EDITORIAL General 020 7880 6200 Editor Nick Martindale nick.martindale@redactive.co.uk Technical editor Jonathan Elliot Sub editor Kate Bennett Designer Carrie Bremner Technical designer Adrian Taylor Picture researcher Akin Falope Publishing and business development director Aaron Nicholls ADVERTISING/MARKETING connections@redactive.co.uk 020 7880 6206

PRODUCTION General production enquiries 020 7880 6209 Senior production executive Rachel Young rachel.young@redactive.co.uk SUBSCRIPTIONS Should you require your own copy of Connections or multiple copies for your staff, subscriptions are available by calling 01580 883844 CONTRIBUTIONS Connections welcomes ideas for contributions.

Please email nick.martindale@ redactive.co.uk

© Redactive Publishing Ltd 2021 Level 5, 78 Chamber Street, London E1 8BL Registered No. 3156216. All rights reserved. This publication (and any part thereof) may not be reproduced, transmitted or stored in any print or electronic format (including but not limited to any online service, any database or any part of the internet) or in any other format in any media whatsoever, without the prior written permission of the publisher.

Redactive Publishing Ltd accepts no liability for the accuracy of the contents or any opinions expressed herein.

Printed by Precision Colour Printing Limited

ISSN 2042-5732

WWW.NICEIC.COM WWW.ELECSA.CO.UK ENQUIRIES Certsure 01582 539000 Communications executive Debbie Shields debbie.shields@certsure.com NICEIC Direct 0333 015 6626 Twitter @officialNICEIC or @officialELECSA Customer services 0333 015 6625 Sales 0333 015 6626 Training 0333 015 6627 Technical helpline 0333 015 6628 Insurance 0333 015 6629

Recycle your magazine’s plastic wrap – check your local LDPE facilities to find out how.

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news

INDUSTRY UPDATE

WATT’S THE MATTER CAMPAIGN ON BENEFITS OF GOOD LIGHTING

Strong demand for WIRE webinars NICEIC and ELECSA’s in-depth technical webinar series, the WIRE, notched an impressive 20,000 viewers in just eight months during 2020.

The webinars, which are free and exclusive to NICEIC and ELECSA registrants, have covered topics such as fault-finding techniques, SPDs, and earthing and bonding. Delivering over 15 hours of CPD approved guidance, the WIRE has proved a hit with those looking to update skills remotely.

“When Covid-19 struck, we identified the need to keep our finger on the pulse when it came to helping customers maintain standards and deliver technical excellence,” said Michaela Keates, NICEIC and ELECSA events and marketing manager.

“As face-to-face events were stopped, the WIRE provided the perfect platform to deliver vital CPD training remotely. It seems to have struck a chord and has proven to be

a much-welcomed resource for our customers.”

The current series has resumed in 2021, and will once again include the popular coding clinic, alongside an inspection and testing mini-series.

Sam Donaghy, NICEIC and ELECSA technical engineering manager, said: “The introduction of the Electrotechnical Assessment Specification (EAS) update will bring CPD into sharper focus. Under these new requirements, those registered with a certification body will be required to document evidence of their CPD. “We will continue to develop exclusive material to ensure NICEIC and ELECSA contractors remain at the forefront of the industry.”

NICEIC and ELECSA are urging homeowners to consider the importance of effective lighting in the home. Through their Watt’s the Matter? campaign the brands are highlighting the health and wellbeing advantages of effective lighting promoting the use of registered electrical contractors for all installation work.

Research to support the campaign found a quarter (25 per cent) of homeworkers say the lighting in their home office is either too dark or too light, with just over half (52 per cent) revealing they regularly suffer from headaches, migraines or eye strain when working.

Almost one in four (24 per cent) people say good home lighting makes them feel better during the winter months, while 27 per cent say decent lighting makes them happier and more energetic.

Paul Collins, NICEIC and ELECSA technical services manager, said: “While it’s great to see more people recognising how better home lighting can help them get through the gloomy winter, have-a-go DIY enthusiasts must remember there’s a huge difference between fitting a new energyefficient lamp and attempting to install a more sophisticated smart solution, which comes with potential pitfalls around electrical safety.

“Our message to consumers is simple – investing in good lighting can be a real mood booster. But always use a professional, such as those electrical contractors listed with NICEIC and ELECSA, for any electrical work – not only to keep your home and family safe, but also to receive the best technical advice and expertise.”

To secure your space on a session or to catch up on previous episodes, visit the NICEIC website’s events section

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Double boost for green tech in 10-point plan More opportunities in low-carbon installations and electric vehicle charging points will be created as a result of the government’s 10-point green plan, announced in November.

The government unveiled a range of green initiatives as part of a £12 billion investment programme designed to help the UK meet its target of eradicating its contribution to climate change by 2050.

The strategy includes plans around offshore wind, hydrogen and nuclear energy. But for electrical contractors, the main focus will be the promise to improve the energy efficiency of homes and public buildings, and the commitment to extend the infrastructure required to charge electric vehicles.

The government pledged to make homes, schools and hospitals greener, warmer and more energy efficient, with a target to install 600,000 heat pumps every year by 2028. In England, this includes extending the Green Homes Grant, which covers around two-thirds of the cost to householders of implementing qualifying energyefficiency improvements such as

heat pumps, solar thermal devices and biomass boilers, up to a limit of £5,000. Lower-income applicants can have the full costs covered, up to £10,000. The scheme will now operate until 31 March 2022.

With electric vehicles, the commitment to invest £1.3 billion to accelerate the rollout of charge points for electric vehicles in homes, streets and on motorways across England will also be welcomed by contractors.

“This is a significant step forward and excellent news for electrical contractors who will be called upon to facilitate the charging infrastructure,” said Paul Collins, NICEIC and ELECSA technical services manager.

Prime minister Boris Johnson also announced the sale of new petrol and diesel vehicles would cease in the UK by 2030, bringing the timeline forward by a decade.

Contractors can get up to speed around new technologies through NICEIC and ELECSA’s Low Carbon Fix podcast, available at www.niceic.com/low-carbonfix or via your favourite podcast provider.

IMAGES: ISTOCK/SHUTTERSTOCK

BUILDING REGULATIONS GUIDANCE IN ENGLAND Following the Hackett Review, the Ministry of Housing, Communities and Local Government has released two new publications designed to provide greater clarity around building regulations in England.

These comprise an enhanced manual for the Building Regulations, designed to be clear and useful for a range of

audiences, and a fully searchable PDF of all Approved Documents.

The publications will be essential reading for anyone working in building services industry and can be found at www.gov.uk/guidance/building-

REMEMBERING TONY CABLE Everyone at Certsure was deeply saddened to hear the news that Tony Cable had passed away in November last year.

Tony had worked in the electrical industry for more than 60 years before he retired in 2017. Having initially completed a six-year apprenticeship, he ran his own business before becoming a college lecturer and joining the NICEIC technical helpline.

His last job was as senior marketing and events engineer, where he played a prominent role presenting videos and hosting sessions at NICEIC Live events.

Alan Wells, former technical director at NICEIC and board member of Electrical Safety First, said: “Tony was engaging and used his extensive practical electrical experience to communicate in a memorable and easy to understand way that resonated with contractors and electricians alike. He had a passion for electrical safety.”

During the course of his career he also helped numerous apprentices into the industry, including working with NICEIC’s own intake and officiating at NICEIC’s Apprentice of the Year competitions.

Speaking at Live South in April 2017 just ahead of his retirement, Tony said: “I have had an amazing career in this industry and met lots of wonderful people. I hope I have managed to pass on a few things that I have learnt along the way.”

He will be much missed, and the thoughts of everyone at Certsure are with Tony’s friends and family.

regulations-and-approved-documentsindex#approved-documents

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18/01/2021 18:05

INDUSTRY INDUSTRY UPDATE UPDATE

MOVE TO POLICE ONLINE ELECTRICAL ITEM SALES

NEWS IN NUMBERS

The proportion of tradespeople who have seen client demand rise since Covid-19 struck, a study by Powered Now suggests

30% The amount of businesses that say they are not clear about the implications of Brexit for their firm, ECA research finds

The proportion of engineering services firms that expect turnover to fall in the final quarter of 2020, according to ECA

Electrical Safety First has put forward its own bill that would make online marketplaces such as Amazon legally responsible for hosting listings of potentially lethal electrical items.

This follows the government’s Online Harms Bill, which focuses on concerns around online personal security. The charity says it fails to address dangerous electrical goods being bought through online marketplaces.

“We campaigned strongly for the government’s Online Harms Bill to include dangerous electricals available online,” said Electrical Safety First chief executive Lesley Rudd.

“Counterfeit or substandard electrical products can have a life-changing impact. Given the sophisticated technologies available to these retail giants, it is not unreasonable to expect them to ensure effective safeguards to stop unsafe electricals being sold on their platforms.”

The bill would force online marketplaces to ensure the safety of electricals sold from a fulfilment centre or third-party seller on their site. They would also have to alert consumers who have bought a substandard electrical item from their marketplace.

The damage Electrical Safety First’s caused by a 2020 annual survey substandard found almost one in four battery charger consumers bought what seemed to be a genuine electrical item from a third-party seller, and found it was fake. It also revealed that one in 10 adults have first-hand experience of an electrical shock or fire from an electrical item bought online.

Electrical Safety First is currently hosting a petition against the sale of dangerous electricals on online marketplaces. To sign, visit www.electricalsafetyfirst.org.uk

162% The increase in sales of battery electric vehicles during 2020, according to the Society of Motor Manufacturers and Traders

The number of CCTV cameras in the UK, up from 4.8m at the last count, according to installation firm CCTV.co.uk

New York, New York Certsure staff kicked off the new year in style as they completed a virtual walk from the company’s headquarters in Dunstable to New York city.

Through logging collective mileage achieved across a number of physical activities such as walking, running and cycling, the workforce completed the 3,439 mile journey and raised an impressive £1 per mile for the Electrical Industries Charity.

On receiving the £3,439, Tessa Ogle, Electrical Industries Charity managing director and CEO, said: “We would like to sincerely thank Certsure LLP for the generous charitable donation. We are a charity created for the industry and with our focus on those within our industry.

It is with your support that we can offer industry members complete support and assistance and, put simply, we couldn’t do it without you.”

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18/01/2021 18:06

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SEE HOW WE’RE CHANGING THE INDUSTRY: WWW.GUARDIANELECTRICAL.CO.UK

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15/01/2021 14:59

INDUSTRY INDUSTRY UPDATE UPDATE

SCOTTISH ELECTRICIAN CONSULTATION STILL OPEN FOR COMMENT The Scottish government is currently consulting on the issue of the regulation of electricians.

The move follows the creation of the Electricians Working Group by the Scottish government, which brought the industry together to try to build consensus for a way forward.

“Although there were a variety of views on how to take specific issues forward, there was unanimous recognition that the system is complex and there is no easy way for a consumer to quickly determine if individual electricians or electrical businesses

are competent to carry out required work,” the consultation states. “It was agreed that the protection of consumers and raising of awareness among consumers was needed.”

According to research by Electrical Safety First, a quarter of UK adults do not use registered electricians, and a third of adults have hired an electrician who has been recommended to them without checking their credentials.

The consultation opened in November and will close on 12 February. It can be found at www.gov.scot/publications/ consultation-regulation-electricians

White paper pledges safety consultation

The electric charging forecourt can charge up to 36 cars at a time

CHARGED UP

The government has announced a consultation on how to ensure social tenants are protected from poor electrical safety, in its long-awaited white paper on the quality of social housing in England.

The move was welcomed by Lesley Rudd, chief executive of Electrical Safety First. “The announcement of a new consultation on electrical safety in the social housing sector provides a much-needed opportunity for the government to end the tenure lottery that currently exists,” she said. “The protection that electrical safety checks afford those in privately rented homes should be extended to those living in social housing.”

The white paper also announced a consultation on mandating smoke and carbon monoxide alarms in social housing, after revealing that around 200,000 social homes are without a working smoke alarm and more than 2.3 million are without a working carbon monoxide alarm. The consultation closed on 11 January.

Paul Collins, NICEIC and ELECSA technical services manager, said: “We welcome the release of this important white paper. Improving safety across social housing is a must and we hope recommendations seen within this document will help bring change similar to that seen within the private sector. We will follow this topic closely and update our contractors as soon as more information becomes available.”

The UK’s first all-electric charging forecourt has opened in Braintree, Essex. Run by Gridserve, the site uses energy from a local solar farm to deliver 350kW of charge.

It can charge up to 36 cars at once, and provide enough charge for around 200 miles of driving in just 20 minutes. Gridserve plans to roll out 100 such sites during the next five years.

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15/01/2021 15:00

VIRTUAL LEARNING

Adapting to the new reality The events of the past year have helped usher in a new era of virtual training, with six of our most popular courses now available through our virtual classroom

L

Neil Vincent is head of training at NICEIC and ELECSA

ast year was the year of Plans A, B and even C as changing circumstances became the new normal.

Training was not exempt, as Covid-19 meant our face-to-face events and courses had to pause on several occasions.

However, opportunities were seized and improvements made.

These included the introduction of our virtual classroom, a platform you have embraced.

Since launching in May 2020, we have delivered 135 courses, reaching more than 1,200 delegates. Initially offering four of our most popular courses – the 18th Edition update, electric vehicle (EV) charging, fire alarm fundamentals and emergency lighting fundamentals – we have worked to expand the offer, which now incorporates two further topics: fire alarm maintenance and emergency lighting design and maintenance.

The emergency lighting design and maintenance course combines our previous unit two design and unit three maintenance courses.

Representing value for money and living up to our values of delivering technical excellence and raising standards, these two courses were identified as being interlinked, so combining them was a logical step.

Focusing on our core objective – delivering the right content at the right time – we have improved flexibility to meet your needs. Back in May, we were running two virtual courses per week; since then, we have steadily ramped up capacity.

We now offer at least one virtual

course every day, with weekend dates available on our most popular course, EV installation.

I also challenged the team to think outside of the box, and we now have a greater ability to tailor courses to meet individual business needs. Companies needing to train multiple operatives can benefit from exclusive sessions, while businesses with specific technical requirements can have course material tailored to meet their objectives.

Many larger customers already took advantage of our bespoke training offer in the face-to-face environment. Thanks to the rollout of the virtual platform, we are unlocking this approach for those wishing to train remotely.

This may be the ideal solution for many businesses looking to upskill in specific areas.

At a time when it seems uncertainty is the only certainty, one thing is set in stone: that our

industry is built upon technical excellence. We must ensure we maintain technical knowhow and competence. NICEIC and ELECSA are committed to helping you achieve this and will continue to provide the tools needed to keep skills up to date.

You also have access to free and exclusive technical guidance through your customer portal.

Here you will find on-demand episodes of the WIRE and indepth technical articles.

The introduction of EAS (Electrotechnical Assessment Specification) 2020 means undertaking and recording CPD is a requirement of your scheme registration, so make sure your records are in order by keeping a log of the learning you undertake throughout the year.

Should you want to discuss your training requirements, reach out to our expert team by calling 0333 015 6627

EAS 2020 What is it? Electrotechnical Assessment Specification (EAS) sets out the minimum requirements for an enterprise (contractor) to be recognised by a certification or registration body as technically competent.

What has changed? The document now requires all contractors registered with a certification body to document evidence of their continuous professional development (CPD) as part of scheme requirements.

What do I need to do? You need to prove you and your operatives are undertaking CPD throughout the year by keeping records. This can be as simple as keeping a spreadsheet detailing the name of the individual, the type of CPD, the date it was undertaken, the amount of time it took, and a summary of key lessons learned.

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19/01/2021 11:42

For faster fixing of electrical boxes in stud walls

Two sizes now available!

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Britclips® RSWB Why mess around with wooden noggins when you can keep a box of RSWB’s on your van? With two sizes now available they will fit any joist divide between 25 and 60cm. Simply screw into the joist at whatever depth you require for your back box. With pre-drilled holes to make fixing even easier, they can also be used to secure conduit and pipes.

Jordan Davies from Amigo Electrical told us: “We use the RSWB as standard now for all our first fixing. It’s so convenient, cost-effective and is a huge time-saver.”

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15/01/2021 15:01

OPTION 1 – BLENDED LEARNING Gain access to the 18th Edition Online Full Course and learn at your own pace, before joining a face to face or virtual classroom for a 1-Day Update Course and Exam.

NOW AT A REDUCED PRICE OF £295

OPTION 2 – ONLINE FULL COURSE Gain access to the 18th Edition Online Full Course, studying online at your leisure to complete the course. You will then need to book your place at your local Exam Centre for your 2-hour exam.

NOW AT A REDUCED PRICE OF £250

OPTION 3 – NEW VIRTUAL CLASSROOM TRAINING You can now continue your professional development virtually. Take the 1-day update course from a location of your choice, whilst using a compatible device.

NEW PRODUCT £185

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TO BOOK YOUR ONLINE COURSE TODAY VISIT SHOP.NICEIC.COM/ TRAINING/18TH-EDITION OR CALL

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15/01/2021 15:02

YOUR P IC T U R E S

2

Caught on camera

1

Trusty NICEIC and ELECSA contractors have been busy uncovering and rectifying dodgy installations and DIY botch jobs. Here are some of the worst offenders from the past quarter

3 4

T

his quarter’s collection of sub-standard discoveries includes: a curtain pole being used as an earth electrode for a large domestic property (1); an unfortunate end for a rodent (2); an electrical shambles in a utility room (3); a fuse board that has seen better days (4); and a piece of MCB improvisation (5).

It continues with: wiring too close to a gas pipe (6); an unwelcome intervention from a plasterer (7); rodent-damaged underfloor cables (8); a spot of plastic recycling including a transformer in the smaller tub (9); and an unearthed light fitting with the line connector melted to the metal (10).

6

5

Thanks to...

8

> Gavin Hyde from Bath-based Sulis Electrical Services > Damian Hayes of Salisbury firm Damian Hayes Electrical > Martin Hampson of Marts and Sparks in Bristol > Robert Cross from Bemish Building Maintenance in Putney > Jim Martindale of Direct Electrical Services in Hull > Mike Valentine of MV Electrical in Weston-super-Mare > Mike Kingman of MDK Electrical Services in Maidstone, Kent > Richard Gates of 365 Electrics in Chart Sutton, Kent > Andrew Figge of AJ Figge Electrical Contractors in Littlebury, Essex > Martin Cheshire of CT Electrical

7 10

Engineers in Warwickshire.

Keep those shots coming in!

Email caughtoncamera@redactive.co.uk

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18/01/2021 17:13

ELECTRICIANS & GAS SAFETY ENGINEERS SCOTLAND NEEDS YOU! Scottish Fire and CO Alarm Legislation has changed and Scotland’s 2.48 million homes require a competent person WR ²W DQG XSJUDGH WKHLU alarm systems by February 2022.

So, the question is are you up to date with your training?

Do you know about the new legislation, could you guide a home owner if asked?

If you need to update your training or become an Expert Installer simply book your free training today at aico.co.uk/expert-installer

#AreYouReady www.aico.co.uk | enquiries@aico.co.uk | 01691 664100 p16_CON.Win21.indd 16

15/01/2021 15:04

CASH FLOW

Get paid on time Having efficient processes to ensure you receive payment for work in a timely fashion is even more important in the current difficult conditions, says Jonathan Amponsah

E

lectrical contractors are all too familiar with the difficulties involved in getting paid on time. It wasn’t long ago that the industry witnessed the shock demise of Carillion and the effects that this had on electrical contractors.

Fast-forward a few years, and we’re all dealing with a bigger global issue – one that has already made a dent in the cash flow of many contractors. To improve your cash flow, you can take the following steps: REVIEW YOUR BUSINESS MODEL While this may not be at the top of your list, it is usually the root cause of most cash flow problems. The pandemic has really exposed this, and scrutiny of the way Carillion conducted business also revealed serious problems with its model. In terms of profit margins, always check whether you are making decent profits on the jobs you undertake and review whether your pricing adequately covers all your direct costs.

Jonathan Amponsah is CEO of The Tax Guys

REVIEW YOUR CREDIT TERMS Every good contract will make it very clear when you must be paid. Avoid offering long credit terms, regardless of who the customer is. In its document Creating a responsible payment culture, the government acknowledges that payment terms beyond 60 days are unacceptable. From a credit control point of view, make sure your contract has clauses relating to late payment interest, recovery costs and liability to pay.

RENEGOTIATE WITH SUPPLIERS Instead of delaying payments to your own suppliers, pick up the phone, be honest and re-negotiate better payment terms.

CUT COSTS Eliminate all unnecessary expenses and only spend on the costs that keep your operational activities going or generate revenue.

PLAN AHEAD FOR TAXES If you have deferred some taxes or reached a payment plan with your suppliers, do plan ahead and watch out for key dates. The first quarter

of this year will be critical when it comes to taxes, as you may be looking to pay personal taxes, payment on account, VAT deferred from the previous year, and VAT due in the current quarter. Pick up the phone and speak to HMRC early to avoid a cash flow crisis.

GET CASH IN EARLY The following eight ways can help you to get cash in early: Use technology to bill on time and send out gentle reminders. With so many apps on the market, you can now bill on the job and let the robots do some of the initial reminders for you.

Offer customers at least three payment options. On your electronic invoices, consider including the usual bank details, credit card and direct debit mandate links. Customers who are on the go can easily click and pay.

Consider incentives for early payment. Here, you can offer a percentage discount if the bill is paid straight away, another discount if customers complete the direct debit mandate, and full price if they pay in 30 days.

Use direct debits. Gone are the days when direct debit facilities were only offered to ‘big businesses’. There are some good online providers of direct debits, so give it a try.

Take a deposit. It’s good practice to request half payment ‘upfront’ and the remaining half on completion of work. Refrain from working for a customer who hasn’t paid you the first deposit.

Review your aged debtors and pick up the phone to talk to customers who have not paid. According to research by debt recovery company Echo Managed Services, 40 per cent of debt gets paid after a telephone call reminder.

Remove yourself from the process. Outsourcing the credit control removes any emotional connection you may have with customers and ensures that your business gets the cash it needs to stay afloat.

Use debt collections letters with interest. If you have them, your credit control department, accountants or lawyers can draft a series of strong debt collection letters and add interest in accordance with your contract.

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DATA NETWORKS

Single connectors Making smart networks as robust and consistent as possible is critical to the functioning of many buildings across a huge variety of sectors, says Brett Smyth

D

ata networks are fundamental to our built environment – and the number of terminations involved can be significant. Each requires attention to detail to ensure a robust and compliant connection, but time pressures, the availability of skilled personnel and congested service voids can all impact the consistency of data terminations.

Conventional field-terminated RJ45 plugs require installers to trim conductors to a precise length before placing the plug onto the cable. If the conductors are too short, open circuits may be discovered during testing; if they are too long, terminations will not look neat and performance may suffer when pairs are exposed outside of the plug body/cable jacket. It’s also easy for a conductor to move during this process, which can go unnoticed until the cables are tested. Both scenarios can result in failed terminations, and it can be difficult and time-consuming to pinpoint the connections that need to be rectified.

To speed up data cabling installations and improve accuracy and consistency, an alternative method is needed that enables right-first-time

accuracy for all skill levels, making the process for Cat 5e, Cat6 and Cat6a cables less fiddly and timeconsuming while error-proofing the network.

Single-piece connectors avoid the need to assemble a three-piece connector, even with CAT6 cable. Conductor wires do not need to be trimmed to a specific length; installers simply remove a section of jacket, remove the centre spline, untwist the pairs into the right order, and trim ends flat.

The cable can then be slid into the connector until seated, with the twisted pairs as close to the pin contacts as possible, and the jacket seated beyond the primary strain relief for a secure connection.

Once the wires are fed through, the installer can pull the cable into the plug, allowing the twists to be pulled to the front of the connector.

This method can improve quality assurance and avoid call-backs across a range of data installation requirements, including CCTV and access control systems, extended patch cords and creation of Cat6 cable backbones for linking data cabinets.

Brett Smyth is general manager EMEA at Ideal Industries

I N FO C U S / MART IN CH E S H IRE How did you come to work for yourself?

What state do they tend to be in?

I joined my dad’s electrical business when I qualified, about 14 years ago.

We usually find at least a code 2, but you can go from one extreme to another. We normally get the remedial works on top.

How has that evolved?

It’s still the same company with me, my dad and his business partner. I’m looking to take it over at the end of this year.

What kind of work do you?

Martin Cheshire, CT Electrical Engineers

Anything domestic or industrial, so emergency lighting testing, fire alarms or putting in new sockets. We’re doing a lot of electrical inspections in private rental properties as well.

Do you do any bigger projects?

We’ve changed around 60 fluorescent fittings to LED in a factory, and we cover a few three-phase customers too.

Might you change things when you take over?

It would be nice to expand, but you don’t want so much work you have to put people off. My

dad wants to carry on for a few days a week as an employee.

Whereabouts do you cover?

We’re based in Atherstone, Warwickshire, so we cover Tamworth, Nuneaton, Coventry and even Leicestershire.

What do you get up to outside work?

I like to play golf, and have also been going to watch Manchester United since I was 12.

If you are a small business or sole trader and would like to feature in In Focus, email infocus@redactive.co.uk

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CASE STUDY

BLOOD BROTHERS Using the government’s ProCure22 (P22) construction procurement framework, the NHS appointed Kier to lead the fit-out of the centre, including the construction of specialist environmentally

Vital organ

BY DAVID ADAMS

A new blood facility in Barnsley is helping NHS Blood and Transplant engage in research and ensure supplies reach patients in time. Sheffield firm HE Barnes played a key role in helping it get up and running

controlled laboratories, clean room, freezer and cold rooms, alongside warehousing and office space. HE Barnes was then selected to provide a full turnkey electrical and mechanical design and build services installation.

HE Barnes was founded in Sheffield by Horace Edwards Barnes in 1923 and remained in family ownership until 2012, when it was sold to its current owners.

Since then the company has focused on growth, including the extension of its service offering, to become a complete turnkey mechanical and electrical services provider.

It now serves clients in multiple sectors, including industrial, retail, leisure, education, residential and healthcare. Turnover is about £30 million and HE Barnes is now part of the broader HEB Group, which also includes a facilities management division. The whole group has several hundred employees, including around 100 at HE Barnes itself.

The £4.2 million project to complete the electrical and mechanical services fit-out at the Barnsley NHSBT centre is one of

IMAGES: JAMES SHAW PHOTOGRAPHY

O

ne of the few positive consequences of the Covid-19 pandemic has been the way it has reminded us all of the true value of the NHS to our society and economy.

But the health service depends not just on the efforts and expertise of its staff, but also on the equipment and facilities they use to deliver patient services and support medical research.

Sheffield-based electrical and mechanical services contractor HE Barnes can claim to have made an important contribution to that work. It delivered a full electrical and mechanical fit-out of the new NHS Blood and Transplant Centre at Capitol Park, near Barnsley, in 2019, with the project handover completed during summer 2020.

NHS Blood and Transplant (NHSBT) manages blood donation services in England and transplant services throughout the UK. Its new centre serves both as a facility for laboratory services, including cell therapy research, and as a location from which the distribution and storage of blood, organs, tissues, bone marrow and stem cells across the country can be coordinated. NHSBT claims the new centre is one of the most advanced facilities of its kind in the world.

The centre replaces two facilities that were located in Sheffield and Leeds – both older buildings that were becoming more expensive to maintain. The new centre has been built inside an existing 7,000m2 shell-and-core building on the Capitol Park business park near Barnsley, close to junction 37 of the M1, to ease the speed and efficiency of distribution processes.

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The new centre is where NHS Blood and Transplant coordinates and carries out many of its vital activities

£4.2M: THE TOTAL VALUE OF THE ELECTRICAL AND MECHANICAL PROJECT

The interior of the facility (below) and (far below) the new back-up generator installed to ensure continuous operation of a facility crucial to NHS operations

the largest and most complex the company has completed. Following the detailed design phase, on-site installation began in 2019 and was completed in March 2020. HE Barnes mobilised a full site-based project delivery management team, with project lead Richard Oadley and electrical project manager Darren Jones heading a team whose size fluctuated between 15 and 30 sitebased operatives, including specialist supply chain partners.

“The team at Barnsley lived and breathed the project from day one,” says HE Barnes managing director Nigel Pollard. “We were often effectively the lead trade in the building and, in conjunction with Kier, were instrumental in ensuring close liaison with NHSappointed fit-out specialists.”

The latter had been appointed to complete fit-out of the laboratories on site. “There were a lot of interfaces between services, so there had to be a lot of collaboration to ensure that when we walked away absolutely everything NHSBT required was available,” Nigel explains.

‘The LV switch room was configured for the original supply capacity switchgear’ ADDED COMPLICATIONS As this was a shell-and-core building, the intake electrical infrastructure was already in place. However, during the detailed design process it became apparent that the existing electrical supply via a 850kVA HV/LV clientowned substation would not meet the facility’s requirements, and would have to be replaced with a 1,250kVA transformer.

“That had a number of knockon effects – it meant the LV panel

and MCCBs we’d procured needed to be upgraded,” says Nigel. “The LV switch room was configured for the original supply capacity switchgear, so we had to ensure that the new, larger substation would actually fit, physically. That proved to be quite technically challenging.

And all of this was happening in a fairly tight timeframe.”

Nonetheless, the complete project – including back-up generator, electrical installations, fire and security systems, mechanical services and a building management system – was completed to deadline.

It was then necessary to complete room-by-room quality assurance and sign-off in line with NHSBT processes. On the HE Barnes side, this was coordinated by Isabelle Wagstaff, who is one of the firm’s project managers.

This final stage of the project was completed despite, as Nigel points out, the coronavirus crisis “striking almost at the critical point, when we were undertaking the commissioning, including a complex, comprehensive and finite verification process”.

He says the company’s board of directors are all hugely proud of the way the team worked in collaboration with Kier, other contractors on site and the NHS stakeholders to ensure a successful delivery of the project, and also of the way the team proved they could adapt to unexpected changes.

“Being involved in a government P22 project on a large scale, and the fact that Kier had the confidence both that we could technically and financially deliver a project of this size, make this project another milestone for our business,” says Nigel. “We have proved we can deliver, which is testament to our people, who are undoubtedly the most valuable asset within our business.”

David Adams is a freelance business journalist

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THE WIRE ON DEMAND Did you know that you can access a whole library of CPD technical webinars on demand through your customer portal?

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15/01/2021 15:06

HO M E OFF IC E S

With more people working from home than ever before, homeowners and employers have an interest in ensuring people have the right set-up to promote physical and mental health.

Lighting is a vital part of the mix

Lightening the mood

BY PENELOPE RANCE

ONE OF THE LASTING LEGACIES

of Covid-19 is likely to be that more individuals and businesses operate at least partly from home on a permanent basis. With this shift has come the realisation that domestic workspaces need to be designed to support not just efficiency, but mental wellbeing as well. Lighting plays an important role in creating positive atmospheres for both work and winding down afterwards, as a growing body of evidence is showing.

A City University London report, Lighting, Wellbeing and Performance at Work, identified lighting as one of several factors in

creating healthy work environments that promote employee engagement, wellbeing and productivity. It found that worker-controlled lighting solutions can enhance work satisfaction, and reduce the likelihood of employee stress, absenteeism and accidents while working. These findings also hold true in the home working environment, as borne out in NICEIC’s own research findings (see box).

Among the ways poor lighting affects performance are physical impacts such as eye strain, fatigue and reduced visual acuity, and physiological ones, by interfering with circadian rhythms. This inhibits problem-solving ability and cognitive performance and can influence mood and interpersonal

relationships – as important over video calls as in the office.

“Our body responds to light biologically, which is why even visually impaired people live within their circadian rhythm, and also mentally, hence the fact that seasonal affective disorder (SAD) impacts so many people during winter months,” says Jay Wilkin, technical director at RAY Lighting.

The understanding of our response to light is increasing all the time. “With discoveries such as the third light receptor in the eye, which regulates our circadian rhythm, and the influence of blue light on the suppression of melatonin, we know that light can have dramatic effects on the body and mind,” says Marcus Steffen, director of MS Lighting Design.

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‘Our body responds to light biologically, which is why even visually impaired people live within their circadian rhythm’

IMAGE: ISTOCK

“Looking at wider research, you can see examples such as night shift work, where the usual routine is disrupted and has an adverse effect on mental health.”

ARTIFICIAL CONCERNS Artificial light can have an extremely negative effect on human wellbeing. Homo sapiens have inhabited Earth for 240,000 years but have only had artificial lighting for 150: just 0.625 per cent, points out Terry John, founder of Lifelight Studio. “We haven’t evolved to deal with artificial lighting,” he says. “Our biological, hormonal and mental systems are attuned to the changes in natural light. It’s unnatural for us to be under artificial light at the wrong time of day.”

The harmful effects are caused by three characteristics of artificial light, including blue light, which is increasingly common due to the popularity of LEDs. “There has been pressure from a regulatory point of view to reduce energy consumption, and lighting has played a major part in that through energy-efficient technology such as LED, which can save 80 per cent compared with traditional incandescent lamps,” says Peter Hunt, chief policy officer of the Lighting Industry Association. “The danger is that this drive for energy efficiency has been at the expense of light quality.”

Add in long hours of screen time, and our blue light consumption has rocketed in recent years.

Almost all LEDs start life as a blue source in chip form. Blue is very bright, does not overheat, and is a simple way to create many lumens.

A layer of yellow and red phosphor is added to create warmer colours.

“This excess of blue in the substrate that we are exposing ourselves to over long periods of time is impacting our bodily rhythm – this includes everything from sleep to digestion,” says Wilkin. Inadequate or poor-quality sleep has a powerful effect on mental health.

Flicker also compromises our wellbeing. Even if we can’t consciously see it, all LEDs flicker, many at 100 per cent, but even the best at 40 per cent. “This not only triggers a stress response in our brains and results in malaise,

LIGHT TOUCH Terry John of Lifelight Studio was employed to survey the lighting at a local authority office set in a converted warehouse and recommend improvements to support staff wellbeing. “They had a high incidence of people suffering with migraines, and high levels of absenteeism,” he says.

There were several factors contributing to these issues. “A number of the ceilingrecessed luminaires had been disabled by the occupants in an attempt to make the illumination feel more acceptable, but this actually made the situation worse,” he says. “Unusually low ceiling height, lack of natural daylight, poor spacing of the recessed luminaires, aggravating contrast levels and, for the space, poor choice of legacy luminaires combined to make the lit environment very poor.”

With no single ‘cure all’ solution, John made a number of recommendations, including raising the ceiling height in the lowest area, installing uniform lighting to reduce the ‘cave-like’ effect, and painting walls white to maximise reflectance values throughout the space. He suggested that task lighting be provided, specified to include controllable light with reduced danger of users accidentally disabling glare.

“Finally, and possibly most importantly, I recommended education of staff on what an effective and healthy lit environment is and how they might adjust behaviours to improve how they feel,” he adds.

anxiety and insomnia, but is also found to exacerbate conditions such as ADHD,” points out Wilkin.

“It makes reading stressful and exhausting as our eyes try to process words in between the flickers.”

The third major issue impacting mental health is long hours spent under the impoverished colour spectrum provided by artificial light. “By using red and yellow phosphor to balance the blue, lamp manufacturers are not faithfully recreating all the colours,” says Wilkin. “Sunlight is generally rated at a colour rendering index (CRI) of 100: we should be making sure our inside environments are as close to this as possible.”

HOME DISCOMFORTS Understanding these issues can help electrical contractors to install more beneficial lighting systems in people’s homes. “Using light to improve the quality of a home office environment doesn’t have to be complicated,” says Hunt.

“Basic principles like providing sufficient light for a task, avoiding glare, creating areas of contrast and using daylight where possible will all contribute to creating a good lit environment.”

One of the key elements is ensuring that there is enough light to work by, as many domestic setups are inadequate. “People are turning spare bedrooms into offices, and the lighting requirements for these two uses are vastly different,” points out Steffen. “A pendant in the middle of the room is not fit for purpose. Office lighting generally tries to achieve 300 lux on a desk. At home, the light levels are usually at 100-200 lux, which are not suitable for long periods of intense work.”

Glare management is vital, as high glare can cause headaches, migraines, and exhaustion.

“Reducing glare by using baffles on spotlight fittings, and fitting dimmers, will make a huge impact on the environment, and thus the users’ mental health,” adds Steffen.

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HOM E OFF IC E S

“Dimming can really help since it gives the client more control over their environment, so they can change it depending on their mood, relieving stress.”

Smart lighting can enhance that control, allowing people to shape their lit environment with greater precision. “Smart lighting systems can respond to fluctuations in daylight levels and provide the right light where it is needed, while saving energy too,” says Hunt.

“Human-centric lighting slowly and imperceptibly changes the colour and intensity of light throughout the day, stimulating the receptors in the eye which control functions such as sleep-wake cycles and alertness.”

This effect is relatively easy to achieve in a home office with a smart task light, controlled by an app to change in colour and intensity throughout the day. “The lamp produces a curve starting with a dose of cold, bluer light to get serotonin levels up, then as it gets towards the end of the day, it goes lower, with redder, warmer light,” explains John.

EDUCATIONAL ROLE Electrical contractors are well placed to help educate people about the importance of the right lighting for mental wellbeing. “Electricians have a lot of influence over what direction a client can take, and there is a huge hole in the market for electrical contractors who can provide holistic advice rather than just putting up rows of downlights,” adds Steffen.

Wilkin believes that, as contractors come to understand more about the available products, they will be better equipped to match them to the human need for light in each specific environment.

“Electrical contractors are able to support clients on every level – from supplying a better-quality lamp

WATT’S THE MATTER? More than half (52 per cent) of people who have been working from home say their mental health has deteriorated during the course of the pandemic, new research by NICEIC has found. The study also found that 55 per cent feel gloomy about the prospect of spending more time at home this winter, with almost four in 10 (38 per cent) saying they feel anxious and fearful.

Poor lighting is adding to the problem, with two-thirds (66 per cent) admitting that this makes them feel more stressed and negatively impacts their concentration levels.

A quarter (25 per cent) of home workers admit the lighting in their home office is either too dark or too light, with just over a half (52 per cent) revealing they regularly suffer from headaches, migraines or eye strain when they are working.

There are signs that the importance of good quality lighting in the home is now better appreciated. Although only 9 per cent have upgraded the lighting in their home office so far, 65 per cent say this is just as important as painting, laying new carpets and buying new furniture. To learn more, please visit www.niceic.com/media/watts-the-matter

that has a warranty and requires zero maintenance, right through to engines, spots and an extensive range of additional innovations.”

John sees opportunities for collaboration in creating and installing beneficial lighting, with contractors raising their profile as part of a network of experts. “As they are at the coalface, interacting directly with consumers, which architects, developers and main contractors might not do, they are a valuable conduit for sharing information on end-users’ wants and needs,” he points out. “This could open up another income stream for contractors.” If they want to specialise in mental wellbeing, contractors can undertake further training. The Lighting Industry

Association offers courses in lighting design that are open to all.

Occupying a niche in this area could become more profitable as employers recognise the value of better lighting in home offices and are willing to fund new installations for home-based staff. “Studies have found an improvement in staff productivity where good lighting design and human-centric lighting has been employed,” says Hunt. “This should be an incentive in itself.”

In some instances, employers have a legal requirement to ensure that their employees have the right lighting, no matter where they are based. The Health and Safety at Work Act means employers are still responsible for the wellbeing of staff working in a home office, and this includes making sure lighting does not have a negative impact.

Ultimately, the aim should not be up-selling clients with the latest technology, but rather finding the right solution. “What we should be selling is the right light,” adds John.

“The light fittings are just the artist’s brush, the tool to apply the light. If the installation is well thought out, then it should last, and it should suit the demographic of people using the space. It’s a much more humancentric approach.”

Penelope Rance is a freelance business journalist

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VA N / TO O L T H E F T

Protect your assets

JOSHUA FLYNN FOUNDED

Bracknell-based Binfield Renewable Solutions in 2011, specialising in the installation of renewable energy and heating technologies. He wasn’t at work when the contents of his van were stolen, in January 2019: it was a Sunday and he’d used it to drive his children into the countryside.

He parked the van in a busy car park. When he returned a couple of hours later, thieves had struck.

“They’d managed to pull the side door open and pulled the deadlock out of position,” he says. “They had taken everything. The only thing they left me was a transformer. I had some hire equipment in there as well. It was an absolute nightmare.”

He later discovered that conditions in the small print on his insurance policy specified that it did not cover theft of tools from the van during the day, meaning he wasn’t even covered.

He estimates it cost around £8,000 to replace the kit, and two days when he could have been working.

Approximately 117,000 incidents of items being stolen from vans were reported to UK police forces between 2016 and the end of 2018, according to What Car? magazine. Figures from the Association of British Insurers show that 2019 saw 19,560 commercial vehicle theft claims settled, up 7 per cent on the previous year. The average amount paid out for a claim in 2019 was £5,700.

EASY PICKINGS There are several problems facing any tradesperson with a van. First, if the name of the business is on the side of the van, this shows thieves there might be something worth stealing.

Second, few vans are impregnable.

Conventional locks can be picked or forced, rear doors crowbarred open and side doors pulled off their tracks.

Given the time and opportunity, thieves may even use power tools to break through padlocks or to rip open the side or roof of a vehicle. Third, it is easy to sell stolen tools.

“The average value of a van’s contents is going up, so the rewards are getting bigger for criminals,” says James Brown, managing director at

BY DAVID ADAMS

Contractors are unable to work without their tools and replacing them can be costly. With thefts from vans on the increase, it’s vital to make sure your vehicle is as secure as it can be

Selectamark Security Systems. “They see it as a quick and easy way to get a lot of money, unfortunately.” Theft of the vans themselves is less common, but is sometimes carried out to order by well organised groups, which steal the most popular vans in order to strip them for parts to sell online.

It is possible to reduce the risk of theft. One way to do so –

inconvenient and time-consuming though it may be – is to unload your tools from the van at the end of the day and store them inside your home or another secure location overnight.

If possible, the van should be parked overnight in a well-lit location, ideally monitored by CCTV and reversed up against a wall. If the van has a side door, the ideal parking

RADIO INTERFERENCE

117,000: THE ESTIMATED NUMBER OF THEFTS FROM VANS BETWEEN 2016-18

If you can’t lock your vehicle, a nearby radio transmitter may be blocking the signal from key to van, says Ford vehicle security specialist Simon Hurr. “Sometimes thieves leave a radio transmitter near a car park for this purpose,” he says. Hold the key close to the

front of your body, then circle the van, keeping the key between you and the vehicle and continuing to try to lock it. When you reach a location from where you can lock it, your body is blocking the source of the interference, which must be somewhere behind you.

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IMAGE: GETTY

space would also leave that door next to a wall, says Simon Hurr, vehicle security specialist at Ford.

Thieves might use skeleton keys to open the front doors, then use laptops to hack digital ignition systems or the On-Board Diagnostics (OBD) port in order to bypass an immobiliser.

Countermeasures do exist, including lockable devices fitted over the OBD port, ignition locks, wheel locks, steering locks and, perhaps best of all, pedal boxes, which can make it pretty much impossible to move the vehicle without picking it up using a crane.

Ensuring a thief cannot get into the back of the van is more difficult, but is possible. Extra protection to foil brute force attacks or attempts to trip central locking systems might include deadlocks, hook locks operated separately from the central locking system, security bezels on door locks, lockable armour shells that fit over the side door and pillar or across the rear doors, and steel anti-peel kits to prevent side doors being pulled open.

AIDING RECOVERY There are also solutions available for marking tools permanently so that if they are stolen they may be recovered later, or – more likely – thieves might be deterred from stealing them because the tools may be harder to sell. Selectamark is

£ £5,700: THE AVERAGE AMOUNT PAID OUT FOR COMMERCIAL VEHICLE THEFT CLAIMS IN 2019

among the companies offering this sort of indelible marking solution.

“You get piece of mind,” says Brown.

“Forensically marking these items is effective and cost-effective.”

If all else fails, insurance can compensate you for the loss of equipment and/or your vehicle, but it’s vital to get the right policy. “We are seeing a lot of underinsured tools claims – for example, someone claiming for £7,000 when there was

only £1,500 worth of cover on the policy,” says Ian Newman, head of SME strategy and development at Covea Insurance, a partner of NICEIC and ELECSA Insurance Services.

Some policies will also only cover the van some of the time and only in certain locations, so make sure you read yours carefully.

It’s also important to provide the insurer with accurate, up-to-date information about your vehicle, its contents and other information, such as where the vehicle is left overnight – all details that will help the claims process run more smoothly. Make a comprehensive list of your tools, keeping serial numbers and receipts for the most valuable items.

There is no silver bullet to prevent the theft of tools from vans, but Tricia Tout, neighbourhood and partnership delivery officer at Avon & Somerset Police, reiterates the fact that there are steps you can take to reduce the risk.

“Criminals will target any weak areas, so the more secure people can keep their vehicles and tools, the better,” she says. “The criminal will find something else to attack if breaking into your van is too difficult.”

David Adams is a freelance business journalist

NICEIC AND ELECSA INSURANCE SERVICES Readers of Connections can insure themselves against van and tool theft through NICEIC and ELECSA Insurance Services, a service managed by Marsh Commercial with specialist insurer Covéa. The standard policy includes public liability, employers liability, professional indemnity and corporate manslaughter cover.

It can be supplemented with optional features, including cover for tools set at limits ranging from £1,500 to £10,000 and for non-specialist work tools such as phones or laptops.

Cover applies at any time – some insurers may only cover tools at certain times – but tools must be kept in a locked vehicle out of sight or in a locked solid building, and there needs to be evidence

of forced entry for a claim to be judged valid.

Paul Buckle, managing director, schemes and affinities, at Marsh, including NICEIC and ELECSA Insurance Services, says the preventative measures insurers view as being the most effective are removing tools from the van at night and reversing the van up against a wall, as well as ensuring vehicles are monitored

by CCTV of some kind, including that provided by digital doorbells.

He agrees that tool-marking and tagging solutions are useful, but warns that there is no single fail-safe way to protect tools against theft. “But this risk is insurable and you can have that claim settled very quickly,” he adds. Go to www.niceic-and-elecsa-insurance.com

29 W I NT E R 2 02 0- 2 1

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CON T RAC TO R P R O F IL E

Brave new world A deal in 2019 saw ownership of Cambridgeshire contractor Wisbech Electrical switch from its founders to a new team of employees

B

ack in May 2019, Cambridgeshire firm Wisbech Electrical finalised a process that saw its ownership transfer from the three surviving original directors to a team of 10 employees, who would all become shareholders in the firm.

The business was initially set up in 1996 by five contracts managers – Phil Ringwood, Neville Pearman, Derrick Blackett, Robert Braybrook and Paul Strickle – who found themselves out of work when local firm DA Rollins ceased trading. It has now entered a new era.

“Out of the 10 who took it over, we have four directors, three engineers out in the field, and three people in administration,” says Marcus Ringwood, who moved from site supervisor to contracts director as a result of the takeover.

His brother Carl is also a contracts director, alongside Aaron Spriggs and Kevin Oughton. Marcus and Carl’s father Phil is one of the former owners, while Tracy and Paula Blackett are the daughters of another founder, Derrick Blackett, and are two of the shareholders working in the accounts team.

Marcus originally joined the company as an apprentice and has now been with it for 20 years, progressing from working as an apprentice to managing small and large-scale projects. “The buyout gave me the opportunity to progress again,” he says. “There was a lot to learn, but I was ready for a new challenge.” The initial plan was for him to focus on tendering for larger projects, he says, but the current market means most of his attention is around small works.

Company Wisbech Electrical Established 1996 Major projects Developing two new factories and installing production lines for Nestlé Purina

RECIPE FOR GROWTH The business, which has been based in dedicated offices in the Port of Wisbech for the past 22 years, has historically worked for food manufacturers, and this remains its main area of focus today. In the early days, Spillers Pet Foods and Premier Foods were major clients, and today Nestlé Purina Petfoods – which took over Spillers – is a core customer. “A lot of the industry around here is based around the food sector,” says Marcus. “That’s been our bread-and-butter over the years.”

Kevin Oughton, who has been with the company for 23 years, has headed up the Nestlé Purina account for the past six years. “They used to always have one factory in Wisbech, but there are now three major factories on the same site

IMAGE: DAVE MCHUGH / UNP

BY NICK MARTINDALE

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Wisbech Electricals directors Aaron Spriggs, Marcus Ringwood, Carl Ringwood and Kevin Oughton (L-R)

producing all the Felix pouches, so we’ve been involved in developing the two new factories and installing new lines or swapping lines round on a constant basis. It’s a 24/7 operation and they produce something like four million pouches every 24 hours. We’ve grown with them, and we’ve travelled around with them too; we’ve been across to France and also to Russia and Hungary installing production lines.”

Other customers in this sector include a local large-scale potato producer, and poultry facilities across the country. But its expertise

in industrial environments has also seen it move into commercial projects for offices and hotels.

The fact that the food sector was deemed essential throughout the coronavirus pandemic meant that the business was less affected than many others. “We haven’t closed completely at all, and have kept around 70 per cent of the workforce working and not furloughed,” says Marcus. “This area isn’t as heavily populated as the cities either, so we’ve been quite fortunate in that we haven’t seen too much interference from Covid-19.”

While much of the commercial work dried up during the pandemic, says Marcus, new regulations around electrical installation condition reports for the private rented sector have seen it take on work in the domestic sector. This is something the business is keen to do more of in the future.

“Although we focus on industrial and commercial work, a core of our team has had experience with domestic, and are all capable of doing it if we need them to,” he continues.

‘We haven’t closed completely at all, and have kept around 70 per cent of the workforce working’

STEADY PROGRESS The business, which employs just under 50 people, takes on work ranging from small-scale projects to multi-million-pound contracts. One of the 2016 contracts was valued around £2.5 million, says Marcus, and firm had it turned around in 17 weeks. Wisbech Electrical would

Marcus Ringwood joined the company as an apprentice and has now been with it for 20 years

be happy to take on similarly-sized projects in future, he adds.

From a recruitment perspective, Wisbech generally relies on traditional advertising, supplemented by a couple of apprentices from a local college each year – although this has fallen to just one this year. “One of the biggest challenges with taking on apprentices is the fact that we work in industrial environments,” says Marcus. He points out that the draw of university and the option of working in more glamorous industries, such as nuclear or aerospace, can also make it hard to attract the right candidate.

While the trials of 2020 meant that last year was simply a case of keeping the business going, the directors are keen to grow during the next few years. “Electric vehicle installations are an obvious area, especially with the recent announcement about petrol and diesel cars,” says Marcus. “We do a lot of that anyway. Then maybe further down the line we will look at renewables because that’s going to be another big thing for the future, for everybody.” The types of facility the business tends to work on would lend themselves to both, he says.

The new owners remain in regular contact with the surviving previous ones, as there are still three and a half years left on a five-year management buyout that will see the price of the deal paid for out of company profits. They are open to the idea of making other employees shareholders in the firm once that is paid off. “That would mean they’re not just getting a wage out of it but a profit-share at the end of the year,” says Kevin. “Once that loan has been repaid then that’s something we can explore a little bit more. But it would be difficult to do that right now.”

Nick Martindale is editor of Connections

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technical

Your industry-leading reference guide to technical information 34

Ask the experts Answers to some of the more frequently asked questions put to our Technical Helpline

36

How to identify current system earthing arrangement Guidance for identifying what type of system earthing arrangement exists at a domestic premises – essential when altering or adding to an existing installation

42

Apprentice Corner This first part of a series on batteries provides an overview of the types of batteries available, the technical terms associated with them, and their typical applications

46

Factors affecting current-carrying capacity of live conductors The aspects to consider when determining minimum live conductor sizes

52

Intro to EESS Part 1 This first part of a series on electrical energy storage systems focuses on operational modes and means of connection

59

Protective Equipotential Bonding Setting out the situations in which protective equipotential bonding is or is not required

THE NICEIC AND ELECSA PUBLISHING TEAM Jonathan Elliott senior technical author Craig Waslin technical author Chris Long technical engineer HELPLINE Sam Donaghy technical engineering manager Duncan McFarlane technical helpline engineer Norman Bradshaw technical helpline engineer Mark Cooper technical helpline engineer Richard Atkins technical standards engineer Mark Barnes-Rider technical helpline engineer Craig Kemp technical helpline engineer Craig Cunningham technical helpline engineer George Georgiou technical helpline engineer Jonathan Dare technical helpline engineer

33 W I NT E R 2 02 0- 2 1

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T E C HN I CAL

Ask the experts

QU E ST I ON

Following on from the question concerning US national standards, what measures must be taken when documenting this installation work on completion?

ANSWE R

We continue with our series of answers to some of the more frequently asked questions put to our Technical Helpline Q UE STIO N

I have been asked to install some equipment in an industrial bakery which was manufactured in the US to their national standards.

Can this equipment be used in the UK? A N SW E R

We are upgrading the supply arrangement for a building supplied from the main distribution board situated in another building some considerable distance away. The upgrade includes conversion of the supply from single-phase to three-phase, however the loading per-phase will not be increased.

Currently the remote building is supplied via a two-core SWA cable.

Would it be acceptable to use the existing two-core cable for two of the phases and to add another identical two-core cable in parallel for the third phase and neutral or some similar such arrangement?

Q

BS 7671 only applies to items of electrical equipment in respect of their selection and application in the installation. The construction of assemblies of electrical equipment must comply with appropriate standards (Regulation 113.1).

In general, equipment may No. Regulation 521.8.1 states be installed in an electrical that where a number of multicore installation in the UK if it cables are installed in parallel complies with: and are used to form one circuit, each • an appropriate British or cable must contain one conductor of Harmonized Standard, or each line. It also states that conductors • in the absence of such a of a circuit must not be distributed across standard, to the appropriate different multicore cables.

International (IEC) standard or the appropriate standard of another country (Regulation 133.1.1).

A

Where there are no such applicable standard(s), the item of equipment concerned may still be installed where selected by special agreement between the person specifying the installation and the installer (Regulation 133.1.2).

Where the equipment used does not meet the requirements of Regulation 133.1.1 or is used outside the scope of its relevant standard(s), the designer or other person responsible for specifying the installation shall confirm that the equipment provides at least the same degree of safety as that afforded by compliance with the Regulations; in this case, in terms of selection of the equipment (Regulation 133.1.3).

Do you have a technical query? Call our helpline on 0333 015 6628

Where the equipment in question meets the relevant requirements of an appropriate standard in accordance with Regulation 133.1.1, an Electrical Installation Certificate can be issued in the normal manner.

Where the equipment used does not meet the requirements of Regulation 133.1.1 or is used outside the scope of its relevant standard(s), this must be recorded on the Electrical Installation Certificate (Regulations 120.3 & 133.1.3).

QU E ST I ON

Under what circumstances can socket-outlets that do not comply with a UK product standard be installed in the UK? ANSWE R

As was the case in the question concerning US national standards, in general, equipment may be installed in an electrical installation in the UK if it complies with: • an appropriate British or Harmonized Standard, or • in the absence of such a standard, to the appropriate International (IEC) standard or the appropriate standard of another country (Regulation 133.1.1).

Additionally, Regulation group 553.1, which deals with plugs and socketoutlets, contains the following requirements that must be met: • Other than for SELV circuits, it must not be possible for any pin of a plug to make contact with any live contact of: (i) its associated socket-outlet with any other pin of the plug completely exposed, and (ii) any other type of socket-outlet installed within the same installation (Regulation 533.1.1) • Other than for SELV circuits, electric clock points, shaver socket-outlets, or a circuit having characteristics such that danger would otherwise arise: • all socket-outlets must be of a

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non-reversible type incorporating provision for a protective conductor (Regulation 553.1.2) • every plug and socket-outlet must comply with the appropriate product standard listed in Table 55.1 (Regulation 553.1.3) • Every socket-outlet for household and similar use must be of the shuttered type and, where used with AC current, preferably of a type complying with BS 1363 (Regulation 553.1.201).

A plug and socket-outlet not complying with BS 1363, BS 546 or BS EN 60309-2 may be used in single-phase AC or two-wire DC circuits operating at a nominal voltage not exceeding 250 volts for electric clock points, shaver socket-outlets, or a circuit having characteristics such that danger would otherwise arise (Regulation 553.1.5).

Q UE STIO N

When carrying out insulation resistance testing during a periodic inspection in an occupied property, is it acceptable to not perform a test between live conductors and instead test between live conductors connected together and the protective conductor at 250 V to prevent damage to equipment or influence on the readings obtained?

A N SW E R

Yes. Regulation 651.2 states that when a periodic inspection is carried out, this should be done without dismantling or with partial dismantling, to minimise the likelihood of introducing an issue where one did not exist previously.

This regulation further states that inspection should be supplemented by appropriate testing and measurements described in Chapter 64, which deals with initial verification of an installation.

Within Chapter 64, the following options are available to minimise the likelihood of damage to equipment or where the presence of connected equipment may affect test results:

• Where appropriate, live conductors may be connected together and the insulation resistance test may be performed between these live conductors collectively and the protective conductor (Regulation 643.3.1).

• Where circuits under test contain electronic devices likely to cause such damage or which may affect results, the insulation resistance test should only be made between the live conductors connected together and the earthing arrangement (Regulation 643.3.3).

• Where it is not practicable to disconnect equipment that is likely to influence the results obtained, or which could be damaged by testing, the insulation resistance test may be performed at 250 V DC, although the minimum acceptable insulation resistance value of 1MΩ remains for low voltage circuits when tested as described in paragraph 1 of Regulation 643.3.2 (Regulation 643.3.2 para 4).

QUEST I ON

What is a limitation and when may it be applied to inspection and testing?

Where I have performed insulation resistance testing either at 250 V DC or between all live conductors connected together to the protective conductor connected to the earthing arrangement, how do I document this on the Electrical Installation Condition Report (EICR)?

Q

The measures described in the question about insulation resistance testing are permitted by BS 7671 in the circumstances described therein, so their use is not a departure or a limitation, and does not need to be stated as such on the EICR. However, NICEIC strongly recommends that you discuss how you intend to perform the installation resistance testing, and indeed other testing, with the person ordering the inspection/testing in advance of work commencing, to minimise the risk of any dispute at a later stage.

Regulation 653.2 requires that details of the extent of the inspection and testing carried out are given on the EICR. A statement clarifying how the insulation resistance testing was performed should be made in the ‘Extent’ field of the EICR. A similar statement should also be made in the field on the Schedule of test results asking for ‘Details of circuits and/ or installed equipment vulnerable to damage when testing’.

A

ANSWE R

The term limitation is not defined in BS 7671. However, in the context of the standard, a limitation is a boundary condition describing what has and what has not been done.

Within Chapter 65 of BS 7671 it is recognised that there may be circumstances where it may not be possible, or reasonable, to inspect all parts of an installation or perform all of the tests as described in Chapter 64 for initial verification purposes when carrying out periodic inspection and testing in accordance with the requirements of Regulation group 651.

Where a limitation is applied to inspection and testing, Regulation 653.2 requires that this is recorded on the Electrical Installation Condition Report (EICR) issued on completion of the work.

The model EICR in Appendix 6 of BS 7671 recognises both agreed and operational limitations, and

includes entry fields to allow these to be recorded.

In general, limitations should be agreed with the person ordering the inspection and testing before work starts. Where during the course of the inspection and testing particular circumstances prevent certain inspection or testing activities from being performed, these should be reported to the person ordering the work as soon as possible. Such operational limitations should be recorded on the EICR. It is important that neither the contractor nor the person ordering the inspection and testing impose unnecessary limitations on the work.

It should be remembered that the greater the extent of the limitations applied during inspection and testing, the less will be its value in terms of verifying the safety of the installation.

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T E C HN I CAL

How to identify current system earthing arrangement O B JE C TIVE

It is essential for electrical contractors to be able to determine the nature of the earthing arrangement when considering additions or alterations to an existing domestic installation. This is especially important where particular requirements may apply, as is the case for electric vehicle charging points and supplies to swimming pools and certain outbuildings. This article provides guidance on how to determine what type of system earthing arrangement exists at a domestic premises originally designed to form part of a TN-S system earthing arrangement.

Introduction The first usage of Multiple Earthing of Neutral (MEN) dates back to the late 1940s, with the use of Protective Multiple Earthing (PME) commencing in the late 1950s.

Nevertheless, substantial parts of the existing low voltage (LV) distribution network were originally wired with cables providing separate neutral and earthing (SNE) conductors and hence suitable to provide a TN-S system earthing arrangement. SNE cable has not been readily available for many years now and so some repair and maintenance on the existing

SNE cabling has, by necessity, been performed using cables designed to provide a combined neutral and earth (CNE) conductor.

This has meant that many installations originally forming part of a TN-S system can now be converted to form part of a TN-C-S supply arrangement where certain conditions are met, such as upgrading of the main bonding arrangement. Where these conditions cannot be met, or the customer does not want the necessary upgrading work carried out, this conversion cannot be offered and the customer will need to arrange for the installation of an earthing electrode so that the property forms part of a TT system earthing arrangement.

Customers may be able to retain their TN-S earthing arrangement where the distributor has been able to carry out certain specific modifications to their network cabling.

In other cases, despite the repair work carried out on the distribution network, it will not be possible for a customer’s earthing arrangement to be converted to TN-C-S, and so they may be able to retain their existing TN-S earthing.

This leaves a problem: how can we determine what supply earthing arrangement exists at a premises originally designed with a TN-S system earthing arrangement?

Requirements for low voltage networks The Energy Networks Association (ENA) publication Engineering Recommendation G12/4 inc AMD1: 2015 Requirements for the Application of Protective Multiple Earthing to Low Voltage Networks gives the requirements for when Protective Multiple Earthing (PME) is applied to Distribution Network Operator (DNO) and 36 W I NT E R 2 02 0- 2 1

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Independent Distribution Network Operator (IDNO) low voltage distribution systems, and to other public distribution systems connected to those systems under the Distribution Code.

The requirements of G12/4 may be supplemented by each Company’s own PME Code of Practice in respect of the detailed engineering and technical requirements of PME application. Therefore it is important that, where any doubt exists, advice is sought from the relevant DNO/IDNO.

Fig 1 Figure 4.5 of G12/4 modified to highlight those sections of the modified distribution cabling suitable to meet PME requirements S/S

Secondary substation

SNE

Link box

S/S

CNE

SNE

S/S

SNE

SNE

Separate neutral and earth cable

CNE

Combined neutral and earth cable Transition joint – CNE neutral connected to SNE neutral and sheath

(see Note 1)

CNE

PME earth electrode

SNE

Meets PME requirements

Updating of existing networks containing SNE cables Underground network cables For underground cable networks, Paragraph 4.5. of G12/4 states that, where PME facilities are available to consumers and CNE cables are incorporated into networks containing SNE cables: • Wherever possible, CNE cables shall be used for reinforcement, diversions and repairs to existing systems. The neutral to sheath bonding and neutral earthing requirements of such systems shall be in accordance with paragraphs 4.4, 4.4.2, Figure 4.4 and any additional requirements shown in Figure 4.5 of that publication.

• An earth electrode shall be provided at the end of the section of CNE cable most remote from the distribution substation. The neutral of each section of CNE cable shall be bonded to the neutral/sheath of the adjacent SNE cable.

The whole of the distributing main between the substation and this earth electrode will then be suitable for PME. • PME can be applied to the remote sections of SNE distributing mains by bonding the earth and neutral conductors at the end of the SNE distributing main and, where necessary, installing an earth electrode.

KEY:

CNE

SNE

(see Note 1)

S/S

CNE

SNE

LB

SNE

S/S

These sections of SNE cable will meet PME requirements if the sheath and neutral are bonded at the end of main and an end of main electrode added.

Branches comprising SNE cable cannot meet PME requirements

New CNE Service (see Note 2) S/S

SNE

SNE

(see Note 1)

Notes: 1. A non-insulated SNE cable in direct contact with the ground will usually provide an adequate earth electrode.

2. An additional PME earth electrode must be added at the end of any branch or service using CNE cable supplying: – more than 4 customers, or – more than 1 customer if length of run exceeds 40 m, or – street furniture with a PME earth terminal.

the DNO. Those existing customers therefore must remain with a TN-S supply arrangement.

However, this may require particular measures to be taken by the DNO. It can also be seen that it is not possible for customers supplied via branches wired using SNE cable to be given a PME facility.

Overhead network cables Paragraph 4.6 of G12/4 states that the principles applied in PME underground systems also apply to overhead systems or mixed overhead and underground PME systems.

When converting systems with a separate earth conductor to PME, all overhead sections of associated main and any other main likely to be used as an alternative supply, between the supply substation and the connection to a consumer being offered PME, must meet the requirements of G12/4.

This may require the installation of additional neutral earth electrodes at intervals along the line in order to maintain the neutral to earth resistance below the required value (see paragraph 4.7).

This criteria is likely to have been met where neutral earth electrodes are installed at intervals not greater than eight spans of the overhead line.

A suitable length of metallic sheath of an SNE cable laid directly in the ground is considered to be an earth electrode. When a new CNE service, or an existing service replaced by a CNE cable, is connected to an SNE distributing main that does not already form part of a PME system, the consumer may be provided with a PME earth terminal, provided that an earth electrode is connected to the neutral at the service joint.

Referring to Figure 4.4 and more particularly to Figure 4.5 of G12/4, reproduced here with modification as Fig 1, it can be seen that a PME facility cannot be offered to some existing consumers having a SNE connection purely on account of where electrodes are added or a bond is made between the sheath of the SNE cable and the neutral of the CNE cable by the DNO, unless further updating work is carried out by

Looped services When alterations are made to any cable associated with a SNE cable looped service arrangement, the earthing systems at the looped 37 W I NT E R 2 02 0- 2 1

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T E C HN I CAL

property and the property connected to the main service must both be connected to the same system earthing arrangement as each other.

This is to avoid the risk of potential differences existing between un-bonded metalwork within the SNE earthed property in the event of an open circuit neutral fault on the main service.

it can be shown by calculation that any voltage rise on the neutral conductor of the three-phase circuit is limited to 100 V. At the junction of the five wire system and the CNE or ABC section, the neutral of the CNE or ABC must be bonded to the neutral and earth of the five wire system and an earth electrode installed.

Where none of these solutions can be applied, a four-core metallic sheathed cable or separate earth conductor should be installed.

The sheath or earth conductors shall be connected to the SNE cable sheath or CEW earth conductor at each end, with the neutral and earth remaining separate.

In the case of domestic or similar installations, earth fault protection may be provided by installing a separate earth electrode such that the installation forms part of a TT system. For some types of special installation or location, it may be necessary to provide a TN-S system earthing arrangement by other means, although discussion of this falls outside the scope of this article.

Paragraph 5.2.1 of G12/4 states that PME earth terminals cannot be offered to consumers where there are reasonable grounds to believe that: • their earthing (and bonding) installation is not designed to BS 7671; or • the type of installation, by its nature/usage/ particular risk factors, is not suitable for PME.

Continued availability of TN-S earthing facility Paragraph 5.1 of G12/4 states that where CNE cable is introduced into SNE networks, existing SNE consumers’ installations may retain an SNE earth provided that: • a continuous metallic earth return path exists to the source substation; and • they are connected to a length of electrically continuous non-insulated metallic sheath cable that is sufficient to control the rise of potential to acceptable levels under open-circuit neutral conditions. This criterion is deemed met provided the resistance to earth of the metallic sheath is 10 Ω or less, or an individual earth electrode is provided with a resistance of less than 10 Ω.

• Where in specific circumstances the 10 Ω value cannot be achieved, a value up to 20 Ω is acceptable where it can be shown by calculation that any voltage rise on the neutral conductor of the three-phase cable is limited to 100 V. If these conditions cannot be met, the DNO will typically offer existing SNE consumers the opportunity to convert to PME, provided that the earthing and bonding within their installation complies with the particular requirements of BS 7671 for where PME conditions apply.

Alternatively, SNE earths may be maintained by running a separate earth cable along with the section of CNE cable. Where this option is chosen, the neutral and earth should remain separate and be constructed so as to minimise the risk of deterioration or damage.

On overhead networks containing continuous earth wires (CEW), when the five wire sections are replaced by CNE cable or four wire aerial bundled conductor (ABC), the G12/4 preference is for all existing SNE consumers to be converted to PME, provided their earthing and bonding complies with paragraph 5.2.1. If not, it may be necessary for them to convert to a TT system earthing arrangement.

Existing consumers beyond a CNE or ABC insert may retain their SNE earth, provided the earth is connected to a sufficient length of SNE cable such that the resistance to earth of the metallic sheath is 10 Ω or less. Where in specific circumstances the 10 Ω value cannot be achieved, a value of up to 20 Ω is acceptable if

Paragraph 5.4. states that where PME facilities are available to a consumer, a label shall be affixed at the service position, drawing attention to the fact that the service is connected to a network having protective multiple earthing.

How can we tell whether an installation designed as part of a TN-S system has been converted for PME/TN-C-S? The presence of one, or preferably more, of the following may be taken as indicators that such conversion has taken place: Fig 2 Example PME notice to be affixed near the intake position/service head

WA RN I N G This installation is connected to a network with protective multiple earthing. It is recommended that electrical equipment SHOULD NOT BE USED out of doors from this installation unless it is protected by a suitable Residual Current Device.

Please consult Blue Sky Power Networks or an approved Electrical Contractor if in doubt about earthing.

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• The customer’s main earthing and bonding meets the specific requirements of BS 7671 for when the PME conditions given in Chapter 54 apply (although there may be instances where the bonding of an installation forming part of a TN-S system as installed originally meets the requirements for PME).

• As, in many cases, the existing main bonding arrangement of an existing premises having a TN-S earth terminal will not meet the requirements of BS 7671 for a PME earthing facility, conversion to PME cannot take place until any necessary upgrading of the bonding is done. The consumer or their agent will have agreed to this upgrading work and this should have been documented in an Electrical Installation Certificate or, more likely, a Minor Electrical Installation Works Certificate. Any such certification should be made available to anyone carrying out further installation work in the premises.

• The original incoming SNE cable is replaced with a CNE cable and a new cut-out suitable for use with PME has been installed. This should be recognisable to an electrically competent person.

• Alternatively, the metallic sheath and armouring of the SNE underground service cable will be connected to the earthing terminal, neutral terminal or neutral connector block as appropriate, by means of a copper conductor of minimum cross-sectional area as specified in paragraph 4.9 of G12/4.

• Wherever a DNO has converted an installation such that PME conditions apply, a label should be affixed on the meter board or otherwise near the service head stating that the installation is now connected to a PME network.

Fig 3 Textbook representations of ‘typical’ single-phase system earthing arrangements at the intake of domestic and similar premises. Left to right: TT; TN-S; TN-C-S (PME). These are probably insufficient for use as the sole means of determining system earthing arrangement

able to recognise where any such upgrading has taken place.

The relevant DNO will either replace the former ‘TN-S service head’ with a ‘PME service head’ or make other alterations at the origin that should be apparent to an electrically skilled person.

It is highly likely that the earthing and bonding will have had to be upgraded, and this work should be covered by a certificate. Any such electrical certification should be made available to those working in the installation after the conversion work.

Probably the most easily identifiable indicator that the earthing arrangement has been changed will be the presence of the warning label advising that the installation now has a PME earthing facility.

However, if for any reason there is any doubt, an enquiry should be made to the relevant DNO to determine what earthing arrangement is in place at a particular premises. Regulation 28 of the Electricity Safety, Quality and Continuity Regulations lists the type of earthing system applicable to the connection as one of the items of information that must be provided on request to any person who can show a reasonable cause for requiring that information.

Such enquiry is especially important as the requirements of G12/4 may be supplemented by each Company’s own PME Code of Practice in respect of the detailed engineering and technical requirements.

Summary Although some DNOs will use SNE cables when extending, modifying or repairing their existing SNE distribution network, others will upgrade their existing networks so that they are suitable for providing a PME earthing arrangement. This will necessitate the use of CNE cables, even in those parts that were originally installed using SNE cables.

In many cases it may be possible for consumer’s installations forming part of a TN-S earthing system to be modified such that it can form part of a TN-C-S system earthing arrangement. This will almost invariably make it necessary to upgrade the main bonding to meet the requirements of Section 544 of BS 7671 where PME conditions apply, particularly where the maximum demand of the installation is increased significantly.

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arranged in a series/parallel network so that the voltage or current respectively (or both) can be raised to desired levels. It is also capable of being recharged.

How batteries are interconnected will be covered in a subsequent article.

Apprentice Corner

Non-rechargeable batteries (primary)

Batteries Part 1 Types and their current ratings This instalment of Apprentice Corner introduces the types of batteries currently available, including the technical terms used, and their typical applications.

However, the construction and chemical processes during the charging/discharging cycle of batteries is outside the scope of this article.

This article will be complemented using a number of multiple-choice questions.

Rechargeable batteries (secondary) This category of battery can be recharged and hence re-used. Though the initial cost is typically more than for a comparable primary battery, when properly used and maintained they do have a significant life span in terms of the number of times they can be discharged/recharged.

Examples of the common types of rechargeable batteries (Fig 2) include: lead-acid, nickelcadmium (Ni-Cd), nickel-metal hydride (NiMH), lithium-ion (Li-ion), and rechargeable alkaline.

Introduction Once considered heavy and cumbersome and only capable of delivering a relatively small current in proportion to their size and weight, advances in battery technology have seen the performance of batteries improve significantly.

Batteries are the primary power source for many electronic and wireless devices, such as mobile phones, laptops, cordless power tools, etc. They are also employed, on a somewhat larger scale, within the electrical installations to provide as a back-up source for many safety services (see Regulation 560.1 of BS 7671) and, more recently, in electrical energy storage systems (EESS).

The zinc-carbon battery (Fig 1(i)) is one of the oldest types still in current use. Its terminal voltage2 is slightly higher than is available, size for size, for the alkaline (Fig 1(ii)) or lithium (Fig 1(iii)) battery. Its current output is the lowest of all the popular non-rechargeable battery types, which makes it suitable for small load applications, such as in torches.

The alkaline battery, when compared to the zinc-carbon, has a higher energy density3 and a longer shelf life. However, the lithium battery outperforms both alkaline and zinc-carbon batteries by a considerable margin. Its energy density is five times greater than the alkaline battery, and 10 times greater than the zinc-carbon battery.

Lead-acid batteries The lead-acid is the oldest battery technology still in common use. They are used mostly for larger power applications where weight is of little Fig 1 Non-rechargeable batteries

Battery types A battery is an electrochemical energy source that can deliver only DC voltage and current.

Batteries are classified into two categories: (i) Primary cells – which are non-rechargeable (ii) Secondary batteries – which can be recharged.

A primary cell is a battery that is designed to be used only once and then discarded.

The functionality of a secondary battery1 is exactly the same as that of a primary cell, but it is typically a group of one or more cells

(i) Zinc carbon

(ii) Alkaline

(iii) Lithium

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Fig 2 Common rechargeable batteries

Lead-acid

Nickel-metal hydride

concern. They are typically used in emergency lighting and for the back-up supply for fire alarm and detection systems, and in some UPS4 systems.

They can be used in home energy storage systems (EESS) as a cost-effective option, but when compared with other types, such as the Li-ion, they have a lower lifespan and depth of discharge (their low energy density means they cannot be stored in a discharged condition).

heavy load and storage at high temperature reduces its service life. The Ni-MH suffers from a considerably greater self-discharge when left unused than a Ni-Cd. One of its main limitations is that it generates more heat while charging and requires a longer charge time than the Ni-Cd. The trickle charge is critical and must be carefully controlled.

Some advanced chargers provide a ‘stepdifferential charge’ which allows for an initial fast charging state before reaching a threshold voltage; at which point the battery is required to cool before entering a state of trickle charge, where the charging current is continually reducing until the battery is fully charged.

Nickel-cadmium Although these batteries are very rarely used today, they are relatively cheap and their discharge rate is very low when compared to Ni-MH batteries. One disadvantage with the Ni-Cd is they have a ‘memory’. This means that the battery will ‘remember’ the point in its charge cycle where recharging began. Therefore, during subsequent uses, voltage will drop at that point as if it had been discharged. It is more viable to use a Ni-Cd battery continuously until it is totally depleted before recharging. When used in conjunction with manufacturer’s instructions, a nickel-cadmium battery can last for 1,000+ cycles before losing capacity.

Nickel-metal hydride These batteries are preferable to Ni-Cd batteries because of their lower environmental impact.

This includes the materials used to construct the batteries and the safe disposal of spent batteries. They have a greater terminal voltage than for Ni-Cd batteries, but less than for alkaline batteries.

The modern Ni-MH battery offers up to 40 percent higher energy density compared to Ni-Cd, powering devices for longer for an equivalent rated battery. However, it is less durable than the Ni-Cd and cycling under

Lithium-ion

Lithium-ion batteries

1 Often called storage batteries.

2 Terminal voltage is the open-circuit voltage which is available before a load is connected.

3 Energy density is the amount energy stored per unit volume.

4 UPS – An uninterruptible power source is an item of electrical equipment that provides emergency power to a load upon mains power failure.

5 Some types may incorporate a reset switch.

There are many types of Lithium-ion batteries, and they are used in a wide range of applications.

They are generally low maintenance, and can resist the ‘memory effect’ whilst tolerating a wider range of temperatures. Their only serious drawback is their fragility, and the need for a protection circuit to keep them working safely, as required under the IEC 62133-2: 2017 standard when used in portable equipment.

Due to their ability for high energy release, these batteries incorporate a fuse that operates on high current and temperature, which may render the battery useless5.

Typically, where individual cells are arranged to form a battery – such as those used in electric vehicles – precautions need to be taken to reduce thermal runaway between cells and prevent the risk of fire. Such precautions generally include thermal protection padding to limit the transfer of heat between cells, and fire blocking foam to suppress any fire.

While the Lithium-ion battery may provide more voltage, it does so at significantly higher

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financial cost compared to a Ni-Cad battery.

However, both will perform for roughly the same number of charge/discharge cycles.

Nominal voltage – batteries are typically marked with a nominal voltage, as shown in Fig 1 and Fig 2. However, a fully charged battery may have a higher open-circuit voltage (OCV) when tested at the terminals.

Charging current – this is the maximum current that can be applied to charge a battery.

Some high performance batteries may allow charging to be carried out at a higher C rating with minimal stress, although manufacturer’s instructions must be taken into consideration.

Charging voltage – this is the maximum voltage that should be applied to the battery to efficiently charge it. As the battery’s voltage starts to rise, the charging current decreases. The charging voltage available must be greater than the battery’s voltage rating.

Discharging current – this is the current that can be drawn from the battery and delivered to a load. If the current drawn by the load is greater than the rated discharging current, the battery drains very quickly, causing the battery to heat up rapidly. For some batteries, this could lead to them exploding. It is essential that manufacturer’s instructions are followed closely when determining the amount of current drawn by the load, as well as the maximum discharging current a battery can withstand.

Shelf life – this defines the time period a battery can stay fully charged before use and then be used for a rated time period. Shelf life is mainly considered for non-rechargeable batteries because those are generally required for immediate use. For rechargeable batteries, even if the shelf time is less, they can be recharged.

Cut-off voltage – the voltage at which the battery can be considered as fully discharged.

Further discharging may cause permanent damage to the battery, in some cases leading to a fire or explosion.

Cycle life – if a battery is fully charged and then is discharged to 80% of its actual capacity, the battery is said to have completed one cycle. The number of such cycles that a battery can charge and discharge defines the cycle life. The more the cycle life the better will be the battery’s quality.

However, if a battery is discharged to, say, 40% of its actual capacity (considering the battery is fully charged initially), it cannot be considered as a cycle life.

Depth of Discharge (DoD) – the DoD determines the overall cycle count of the battery.

A battery having a small discharge or low DoD will typically last much longer, due to enduring less stress.

It may be considered as a fraction or percentage of the capacity which has been removed from the fully charged battery. DoD is defined as the capacity that is discharged

Technical terms used while dealing with batteries There are a number of terms used to explain the characteristics of a battery. These terms include: Battery capacity – this is a measure of the charge stored by the battery and is determined by the mass of active material contained in the battery. The battery capacity represents the maximum amount of energy that can be extracted from the battery under certain specified conditions – namely current loading, temperature and battery age, amongst other things.

As energy is the product of power and time (P × t), it is expected that the energy stored in a battery would be measured in Watt-hours (Wh). However, since Wh = U × I × h and because the voltage is usually fairly constant, the unit representing battery capacity becomes Ah or mAh. The Ah rating on its own means very little without knowing what hour rate was used.

C-Rate – this is the amount of current that a battery can deliver (or discharge) over a given time and is termed its C-rating. It is closely related to the battery Ah capacity.

Example: A battery is marked as 22 000 mAh (22 A) at 22.5 V and 20 C. Maximum discharge current = mAh × C – rate = 22 × 20 = 440A The battery would be incapable of supplying this amount of current for any appreciable length of time as the battery voltage would very quickly diminish. A more acceptable discharge rate would be 1 C (22 A) or less.

Table 1 shows how different C ratings affect the capacity of a 1 Ah rated battery.

Note: The higher the C-rating, the greater the current that can be drawn from the battery.

Table 1: C-rate for a 1 Ah battery (charging and discharging times) C-rate

Time

5C

12 min

2C

30 min

1C

1h

0.5 C or C/2

2h

0.2 C or C/5

5h

0.1 C or C/10

10 h

0.05 C or C/20

20 h

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from a fully charged battery, divided by battery nominal capacity.

Area Engineer / Mick Maye When did you first become an area engineer for Certsure?

Back in 2015 when Certsure LLP was created. I had previously worked as an assessor for ELECSA and ECA.

Multiple-choice questions 1. A primary battery is a battery where: a) The electrochemical reaction is not reversible b) It can only be charged and discharged once c) It can only be used as a back-up energy source d) It can be charged and discharged many times 2. The capacity of a battery is expressed in terms of its: a) Current rating b) Voltage rating c) Ampere hour rating d) Depth of discharge 3. Which of the following are generally used in a domestic electrical energy storage systems? a) Nickel-cadmium battery b) Lead-acid battery c) Nickel-metal hydride d) Rechargeable alkaline battery

How has the job changed in that time?

The biggest change has been the use of iPads instead of having multiple pages of handwritten reports.

This is a huge advantage for me, as I don’t have the best handwriting!

Mick Maye Northamptonshire and surrounding counties NICEIC and ELECSA employ 80 field team staff to assess contractors’ work and provide up-to-date technical advice. To many of you they will be the face of NICEIC and ELECSA that you see regularly. Here we turn the tables and put them in the spotlight

4. Trickle charging of a storage battery helps to: a) Increase its loading capability b) Reduce its reverse capacity c) Improve its cycle life d) Keep it in a ready-to-use condition

What are some of the biggest changes within the industry that you have come across in that time?

From the one-man bands to the nationals, they are all now aware of how social media can have a both positive and negative effect on their business in a very short space of time.

What’s the strangest thing you have come across on an assessment?

Ladies wearing certain attire at a club I attended as part of a contractor assessment in Coventry Street in London. I can say no more…

What interesting jobs have some of your contractors been involved with?

Quite a few. Notable ones include the new elephant enclosure at Whipsnade Zoo, penguins at Twycross Zoo, airport runway lighting, Silverstone Racing Circuit, and the Vodafone UK transmission site.

5. The output voltage of a battery charger is: a) Higher than the battery voltage b) Less than the battery voltage c) The same as the battery voltage d) Ripple-free low voltage DC

What are your interests outside of work?

Collecting rare soul vinyl, clay shooting and Guinness.

If you could have a superpower, what would it be?

Time travel. Just imagine how you could change things!

6. A battery casing is marked 25C to 40C. This means that: a) The battery will discharge in 1 hour when suppling a load current between 25 A and 40 A b) The battery will discharge in 1 hour at 25 A if the ambient temperature is less than 40 °C c) 25C is the normal discharge rate and 40C is the maximum burst discharge rate d) 40 A is the absolute maximum the battery can supply to a load without damage

If you had a day off tomorrow, what would you do?

Chill out and maybe go clay shooting. Nothing too strenuous!

Favourite book, film and TV programme?

Book: BS 7671 (not!).

Film: I prefer comedy films. Anything Rik Mayall and co. did.

TV programme: Game of Thrones was good and I really liked the series Killing Eve. What’s the best bit of advice you would give to electrical contractors?

Be honest and professional to clients and employees at all times.

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Factors affecting current-carrying capacity of live conductors

O B JE C TIVE

Correcting the current-carrying capacity of a cable for ambient conditions

This article will consider the effect of ambient conditions and installation methods when determining minimum live conductor sizes.

BS 7671 often specifies a minimum crosssectional area for live conductors. In some cases, the purpose of the minimum dimension is for the conductor to be sufficiently resilient to the mechanical damage likely in a particular application or environment.

In most cases, the limiting factor is currentcarrying capacity. However, any quoted minimum size will not have taken into account any external factors that may reduce this.

Whilst the specified minimum size might be adequate in some cases, it will often be necessary to take into account a range of other influences that could affect current-carrying capacity, such as: • ambient conditions in relation to external influences as detailed in Section 522 of BS 7671 • installation methods, conductor arrangements, presence of insulation materials and the like covered in Section 523.

The cross-sectional area (csa) of live conductors must not be less than the minimum sizes stated in the relevant part of BS 7671, such as Table 52.3 (general), Table 55.2 (auxiliary circuits) and, where applicable, in various sections in Part 7 covering special installations/locations (524.1).

The current to be carried by a conductor for sustained periods during normal operation should not result in the appropriate temperature limit specified in Table 52.1 of BS 7671 being exceeded (523.1).

The requirement of Regulation 523.1 is considered to have been met if the current carried by a non-sheathed or sheathed cable does not exceed the values given in the appropriate current-carrying capacity tables in Appendix 4 of BS 7671, taking account of the installation method employed (Table 4A2) and after the application of any relevant rating factors (523.2).

The appropriate value of current-carrying capacity may also be determined: • using the methodology described in the BS 7769 (or BS IEC 60287) series, or • by test, or • by calculation using a recognised method, provided that the method used is stated.

Voltage drop as described in Section 525 can also be the limiting factor when determining minimum conductor size, but is not considered in this article.

The characteristics of the load and, in the case of buried cables, the effective thermal resistance of the soil should be taken into consideration (523.3).

Introduction

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Installation method Table 4A2 of Appendix 4 lists the different installation methods and their related reference method codes recognised by BS 7671.

The installation method affects the rate of heat dissipation and hence the currentcarrying capacity of a cable. For example, the current-carrying capacity of a cable clipped direct to a surface is generally higher than that of the same cable enclosed in conduit or trunking, as the enclosure inhibits the escape of heat from the cable.

The current-carrying capacity of a cable, as outlined in Appendix 4 of BS 7671, normally relates to the maximum temperature at which the conductor can operate continuously without causing damage to the cable insulation or sheath, terminations, connected equipment and surroundings such as building materials.

Fig 1 No grouping factor is required where cables are spaced two diameters apart

Perforated cable tray

d

3-Core SWA cable 2xd

d = Cable diameter

in the group should be based on the lowest maximum operating temperature of any cable in the group together with any appropriate group reduction factor.

If it is known that a non-sheathed or sheathed cable will carry a current not greater than 30 % of its grouped current-carrying capacity, it may be ignored when determining the reduction factor for the rest of the group. The factors only apply to grouped cables where the range of conductor sizes in the group spans not more than three adjacent standard sizes and the current-carrying capacity of all the cables is based on the same maximum permissible conductor temperature – see Note 3 to paragraph 2.3.2 of Appendix 4. For more information relating to mixed size cables see Appendix 4.

It should be noted that where the external distance between adjacent cables exceeds twice their overall diameter, as illustrated in Fig 1, it is not necessary to apply a correct factor for grouping.

Ambient temperature For the purposes of BS 7671, ambient temperature is the temperature of the medium surrounding a non-sheathed or sheathed cable when it is not loaded (523.4). The currentcarrying capacity of a cable reduces as the ambient temperature surrounding the cable increases.

The current-carrying capacities tabulated in Appendix 4 of BS 7671 are based on the following ambient temperatures: • 30 °C – Non-sheathed and sheathed cables in air, irrespective of the installation method.

• 20 °C – Buried cables, either directly in soil or in ducts in the ground.

Where ambient temperature differs from the above values, the appropriate rating factor (Ca) given in Tables 4B1 (for cables in air) and 4B2 (for buried cables) should be applied to the tabulated current-carrying capacities set out in Tables 4D1A to 4J4A.

Number of loaded conductors When calculating current-carrying capacity, only those conductors carrying load current should be considered.

Neutral conductors of balanced polyphase circuits do not need to be taken into consideration.

A neutral conductor should be considered as a loaded conductor where the third harmonic, or multiple of third harmonic, presents a total harmonic distortion greater than 15 % of the fundamental line current (523.6.1).

Where the neutral conductor in a multicore cable carries current, as a result of an imbalance in line currents, the temperature rise due to the neutral current is offset by the reduction in the heat generated by one or more of the line conductors. In this case the conductor size should be chosen on the basis of the highest line current. In all cases the neutral conductor should have an adequate cross-sectional area to

Groups of more than one circuit Where cables are grouped together, unless they are spaced sufficiently far apart, their currentcarrying capacity is reduced. The derating factor used to take account of this is referred to as the grouping factor (Cg). Tables 4C1 to 4C6 of Appendix 4 of BS 7671 contain grouping factors applicable to a range of cable types and installation methods.

Group reduction factors are applicable to groups of non-sheathed or sheathed cables having the same maximum operating temperature. For groups containing nonsheathed or sheathed cables having different maximum operating temperatures, the current-carrying capacity of all the cables 47 W I NT E R 2 02 0- 2 1

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ensure that the conductor temperature limit is not exceeded (523.6.2).

Fig 2 Variation in conductor size to allow for change in ambient temperature

Variation of installation conditions along a route

6.0 mm2 4-core SWA cable

Heat dissipation can vary along the length of a circuit. Where this is the case, the currentcarrying capacity of a cable should be appropriate for the part of the route where it is installed (523.8).

DB1

Wherever possible, cables should be placed so that they are not covered by insulation. Where this is not possible, the cross-sectional area of the cable should be selected taking into account the reduction of current-carrying capacity caused by the degree of insulation coverage.

Tabulated current-carrying capacities are given in Appendix 4 of BS 7671 for cables installed in a thermally insulating wall or above a thermally insulating ceiling and the cable being in contact with a thermally conductive surface on one side. Where these tabulated values are used, it is not necessary to apply a rating factor (Ci) for thermal insulation.

Where a single cable is totally surrounded by thermal insulation over a length of 0.5 m or more, the current-carrying capacity must be taken as 0.5 times the current carrying capacity for that cable clipped direct to a surface and open (Ci = 0.5).

Where a cable of up to 10 mm2 is installed totally surrounded in thermal insulation for less than 0.5 m, the appropriate factor given in Table 52.2 of BS 7671 should be applied to determine its current-carrying capacity.

This requirement also applies where cables pass through fire-stopping material in, for

10 mm2 4-core SWA cable

Hot plant room ≤ 45 °C

DB2

example, trunking where cables pass through penetrations in walls, ceilings, floors etc. as this has effectively removed any ‘free air’ from around the conductors at that point in the enclosure as illustrated in Fig 4.

Neutral conductors Regulation 524.2.1 states that the neutral conductor of a circuit should have a crosssectional area not less than that of the associated line conductor(s) in: • Single-phase, two-wire circuits in all cases, and • Polyphase and single-phase three-wire circuits where the cross-sectional area of the associated line conductors is less than or equal to: • 16 mm² for copper conductors, or • 25 mm² for aluminium conductors • Situations, such as where there is significant harmonic current in a three-phase circuit, where the neutral conductor carries current without a corresponding reduction in current in the associated live conductors (523.6.3).

Fig 3 Installation methods to be applied to flat-twin and earth type cables in thermal insulation

101

Fire stopped

Room at normal ambient temperature ≤ 30 °C

Cables in thermal insulation

100

Metallic adaptable box where conductor size increases

Fig 4 A thermal insulation correction factor may need to be applied where cables pass through walls in trunking

102

103

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For the purposes of Regulation 523.6.3, a harmonic current is considered significant where the total harmonic distortion due to third harmonic current or multiples thereof is greater than 15 % of the fundamental line current.

Where the total harmonic current due to triplen harmonics exceeds 33 % of the fundamental line current, it may be necessary for the neutral conductor to have a larger cross-sectional area than its associated line conductors (524.2.2).

In polyphase circuits where each line conductor has a cross-sectional area greater than: • 16 mm² for copper conductors, or • 25 mm² for aluminium conductors

Apprentice Corner answers 1.

Correct option is (a) A primary battery can only be used the once and must not be recharged.

2. Correct option is (c) The ampere hour (Ah) provides a measurement of battery capacity, although the relationship between battery capacity and the rate of discharge is not a linear one. For example, a 100 Ah battery will not provide 100 A for one hour. It would however provide, say, 20 A for five hours whilst maintaining a voltage close to its terminal voltage.

The cross-sectional area of the neutral conductor may be smaller than the associated live conductors where all of the following criteria are met: i.) the maximum current in the neutral conductor in normal service, including any harmonic current component, does not exceed the current-carrying capacity of the reduced cross-sectional area neutral conductor, and ii.) the neutral conductor is protected against overcurrent in accordance with Regulation 431.2; that is, overcurrent detection appropriate to the neutral conductor’s cross-sectional area is provided, arranged to disconnect the live conductors, but not necessary the neutral conductor, and iii.) in any case, the cross-sectional area of the neutral conductor should be at least: • 16 mm² for copper conductors, or • 25 mm² for aluminium conductors.

3. Correct option is (b) 4. Correct option is (d) 5. Correct option is (a) The rate of current flow when charging a battery in a discharged state can be high.

It is for this reason that ‘smart chargers’ are recommended, which limit the charging current to a safe level throughout the charging period. The charging voltage must be high enough to overcome the battery’s internal resistance to permit the charging current to flow.

6. Correct option is (c) The charge and discharge rates of a battery are governed by C-rates. If, for example, the capacity of a battery is rated at 5 200 mAh, the maximum discharge current is 130 A (5.2 x 25) but can give a current burst of 208 A (5.2 x 40).

Summary A number of factors must be taken into account when determining the minimum cross-sectional area of live conductors.

Even where BS 7671 states a minimum conductor size based on mechanical strength and durability, in many cases this will be insufficient when the ambient conditions that are present in the installation in which the conductors are installed are taken into consideration.

As a result, an assessment must be made of any such ambient conditions present in a particular installation, and current-carrying capacity must be corrected accordingly such that the current carried by a conductor for sustained periods during normal operation does not result in the appropriate temperature limit specified in Table 52.1 of BS 7671 being exceeded.

When determining the corrected currentcarrying capacity of a conductor, any and all relevant factors affecting this should be taken into consideration. Appendix 4 of BS 7671 provides guidance on how this is done.

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Intro to EESS part 1 there is no local generation capacity. It can also provide a reduced reliance on the public supply network.

This article concentrates on the means of connecting such a system to an installation and the range of operational modes that an EESS can provide.

O B JE C TIVE

This is the first in a series of articles looking at the provision of electrical energy storage systems (EESS). It concentrates on the operational modes that may be employed and the means by which the storage media is connected to the host installation and embedded generation, if any.

Future articles will focus on other aspects of such storage systems in greater depth.

Nature of the system An EESS may be designed and built for a particular application or it may be assembled from a range of component parts to provide the desired functionality.

One of the most critical aspects of any EESS is how it is connected to the sources of supply and loads.

Introduction An increased focus on energy efficiency, in conjunction with the wider availability of cost-effective small-scale generation and the significantly reduced availability of new attractive feed-in tariffs, has seen an increase in the installation of local electrical energy storage systems (EESS) at a wide range of properties, including domestic premises.

This is reflected in Amendment No2 of BS 7671, due for publication in 2022, which will introduce a new Chapter 82 – ‘Prosumer’s lowvoltage electrical installations’1. This contains requirements and recommendations relating to the delivery of locally generated energy into the public supply network and/or for use to supply loads locally.

The installation of an electrical energy storage system (EESS) provides a means to store surplus energy generated locally: • either for use within an installation at some later time, or • for export to the public supply network for financial gain.

Fig 1 AC-coupled, grid-connected system with local generation (not capable of off-grid operation) OUTGOING CIRCUITS

POWER CONTROLLING EQUIPMENT

DISTRIBUTION BOARD

AC ENERGY PRODUCTION METER

DC 2-WAY FLOW

ISOLATOR

ISOLATOR

IMPORT/EXPORT METER

ISOLATOR

INVERTER

INVERTER

BATTERY CHARGER/ DISCHARGE CONTROLLER

SERVICE HEAD

SINGLE WAY FLOW

ISOLATOR PV ARRAY

ISOLATOR

DNO NETWORK

FUSE BATTERIES

An EESS can also be employed to store energy taken from the public supply network where 52 W I NT E R 2 02 0- 2 1

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Fig 2 DC-coupled, grid-connected system with local generation (not capable of off-grid operation) OUTGOING CIRCUITS ENERGY PRODUCTION METER DISTRIBUTION BOARD

AC DC 2-WAY FLOW

ISOLATOR

SINGLE WAY FLOW

ISOLATOR

IMPORT/EXPORT METER

INVERTER PV ARRAY ISOLATOR BATTERY CHARGER/ DISCHARGE CONTROLLER

SERVICE HEAD

ISOLATOR

Operational modes

DNO NETWORK

FUSE BATTERIES

Connection may be made by either: • AC-coupling – where both input and output operate at 230/400 V; 50 Hz AC. This is beneficial for the direct supply to AC loads within the premises, but also requires the installation of an inverter and charge control equipment to convert the supply to the storage batteries to DC for charging purposes and from DC to AC to supply AC loads (see Fig 1).

If a battery storage system is added to an existing solar PV system it is likely that it will be AC-coupled as so doing will be easier and cheaper than adding a DC-coupled system.

1 BS 7671 defines a prosumer as an entity or party which can be both a producer and a consumer of electrical energy

Fig 3 Self-generated energy usage against time as part of time shifting strategy

+

Battery Storage

– 0

3

6

However, in the long term, a DC-coupled system will offer higher operational efficiency and greater flexibility.

• DC-coupling – where both input and output operate using DC. This allows for the charging of batteries via a DC/DC convertor – with significantly higher efficiency than an AC supply via inverter/charge controller as there is only one stage of inversion, minimising losses (see Fig 2).

It also allows for the provision of a direct supply of DC loads within the premises.

Although not common currently, this is likely to become more commonplace in the future as installations contain more distributed DC circuits.

A DC-coupled system is likely to be installed in the majority of new combination PV/energy storage systems due to its higher intrinsic efficiency.

9

12

15

18

21

0

24 Hrs

Once batteries capacity reached, excess energy exported to grid Batteries near charge capacity Embedded PV generation charges the batteries Stored energy is greatly reduced Stored energy consumed by the installation Surplus stored energy exported to grid

A number of operational modes are available to meet a diverse range of customer needs.

These modes of operation will directly influence design considerations, equipment selection and system complexity.

A customer may want an EESS installed in their premises for a number of reasons, including: • Time shifting – this is the ability to make most effective use of any excess self-generated energy within an installation at a time when it is needed, or when the embedded generation is not producing energy, or is minimally productive. An example of this would be a PV system at night and on dull days. Fig 3 shows an example of how such a system may operate over a 24-hour period.

• Value optimisation – where an installation is supplied on a variable tariff, energy can be bought at lower cost (off-peak) times and stored locally for use as an alternative to the public supply at times of peak demand/highest cost employing time-shifting. Such a system can be employed in premises where there is no embedded generation capacity and can provide a significant saving over time in some cases. Fig 4 shows a typical arrangement for such a system.

• Alternative supply – this can be arranged to provide a back-up source of energy for a complete installation, core parts of the installation, or at least those parts for which continuity of supply is necessary (see Fig 5).

Where a system is employed to provide an alternative supply, the design must ensure adequate availability of capacity to meet the expected energy demand.

53 W I NT E R 2 02 0- 2 1

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T E C HN I CAL

Fig 4 Basic AC-coupled, grid-connected system. No local generation

OUTGOING CIRCUITS

POWER CONTROLLING EQUIPMENT DISTRIBUTION BOARD

AC

ISOLATOR

DC 2-WAY FLOW SINGLE WAY FLOW INVERTER

ISOLATOR

BATTERY CHARGER DISCHARGE CONTROLLER

IMPORT/EXPORT METER

ISOLATOR SERVICE HEAD

FUSE

DNO NETWORK

BATTERIES

Fig 5 Arrangement showing alternative supply to serve essential loads in the installation in the event of DNO supply failure

OUTGOING CIRCUITS

OUTGOING CIRCUITS

GENERAL LOAD DB

ESSENTIAL LOAD DB

AC DC 2-WAY FLOW SINGLE WAY FLOW

ISOLATOR

CONTACTOR (CONTACTS CLOSED WHILE DNO SUPPLY CONNECTED)

Requirements for earthing and switching will be covered at greater depth in a later article.

ISOLATOR

NEUTRAL-EARTH SWITCHING CONTACTOR (CONTACTS OPEN WHERE DNO SUPPLY CONNECTED)

IMPORT/EXPORT METER

INVERTER PV ARRAY

SERVICE HEAD ISOLATOR BATTERY CHARGER/ DISCHARGE CONTROLLER

DNO NETWORK

An EESS operating in island mode – that is, where supply is maintained from embedded generation or energy storage although the supply from the grid has been disconnected – cannot rely on the earthing arrangement provided by distributor when running independently of the DNO supply (551.4.3.2.1).

This does not mean, however, that the distributor’s means of earthing must be disconnected during such operation.

Energy Recommendation G99 Requirements for the connection of generation equipment in parallel with public distribution networks on or after 27 April 2019, published by the Energy Networks Association (ENA), requires provision of the following when an EESS operates in island mode: • An earth electrode system independent of the earthing arrangement for the grid connection. Any such electrode(s) must have a sufficiently low impedance to allow for the correct operation of protective devices/equipment.

• A means to break all poles of the supply, including the neutral, to prevent transfer of any phase or neutral current produced by the embedded generation from passing into the public distribution network.

• A means to connect the neutral and earth of the embedded generation just after, but at substantially the same time that, all poles of the supply are disconnected. This is to prevent incorrect operation of RCDs within the installation.

ISOLATOR

FUSE BATTERIES

• Grid independent operation – to provide reliability of supply with only self-generated energy employing for example time-shifting (as described above).

Any grid independent system must be provided with an earth electrode system having a sufficiently low impedance to allow for the correct operation of protective devices/equipment.

• Additional supply capacity – to work in conjunction with an existing grid supply to make possible expansion of the electrical load of the premises whilst avoiding the need to have a potentially costly upgrade to the incoming supply arrangement. Such a system may be particularly useful to small businesses whose energy usage has increased as their business expands.

• Peak lopping – somewhat similarly to the provision of additional energy supply capacity, embedded generation/storage capacity can

54 W I NT E R 2 02 0- 2 1

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Fig 6 Use of embedded generation/energy storage to meet peak demands exceeding agreed DNO supply limit

+ Peak loads met by embedded generation capacity

Power Demand

Agreed DNO supply limit

General load met by DNO supply capacity

– 0

3

6

9

12

15

18

21

24

Time of Day

also be used to supply any peak demand exceeding the agreed public supply capacity, so avoiding costly financial penalties (see Fig 6).

Summary Due to an increased focus on energy efficiency, particularly in conjunction with the wider availability of cost-effective small-scale generation, there has been an increase in the installation of local electrical energy storage systems (EESS).

This article, the first of a number looking at electrical energy storage systems (EESS) describes a range of operational modes which may be provided by an EESS and the typical means for connecting such systems into an installation.

The next article in this series will concentrate on examples of key terminology used and descriptions of the component parts required in an EESS.

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T EC HN I CAL

Protective Equipotential Bonding changed in 1969. Part of these changes meant that it became illegal to use lead pipes for the supply of water and so the use of plastic such as medium density polyethylene (MDPE), as shown in Fig 1, was introduced.

O B JE C TIVE

There is often confusion concerning the requirements for protective bonding given in Regulation 411.3.1.2, especially where there are transitions from metallic to plastic pipes entering a premises. This article will clearly show where protective equipotential bonding is and is not required.

Protective equipotential bonding 1 When the type of material used for the service pipework is not easily discernible, a continuity test should be carried out.

The purpose of protective equipotential bonding is to minimise the magnitude of touch voltages that can arise during an earth fault condition.

An example of this will be considered further into the article.

Fig 1 Water and gas service pipework

Introduction Carrying out protective equipotential bonding where there are metallic parts entering a premises has been a requirement of the IEE Wiring Regulations (subsequently BS 7671) for decades. In the 14th Edition (1966) of the Regulations For The Electrical Equipment of Buildings, Regulation D.10 required a connection from the consumer’s earthing terminal be made to the metalwork of any public gas services and any water services on the consumer’s premises.

Similarly, Regulation 411.3.1.2 of BS 7671 (2018) states that in each installation, main protective bonding conductors shall connect extraneousconductive-parts to the main earthing terminal (MET), and includes a list of examples that identifies such types of extraneous-conductiveparts1. It is clear that little has changed in the requirements for protective bonding in more than 50 years.

For many premises built before 1970, there is every likelihood they will have lead pipes for the water supply. Because of the health dangers associated with the use of lead to supply drinking water, the Building Regulations

Metallic Water & Gas Services TN-C-S

Medium Density Polyethylene (MDPE) Water & Gas Services S AF E T Y ELEC T R I C AL CO NNEC T I O N D O NOT R EMO V E

S AF E T Y ELEC T R I C AL CO NNEC T I O N D O NOT R EMO V E

* 1

3

2

No extraneous-conductive-part, no protective bonding required

*Extraneous-conductive-part 1. LV supply

2. Water service

3. Gas service

Note: The water suppliers stop tap, typically located at the boundary of the property, has been omitted for clarity.

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T E C HN I CAL

An earth fault current is defined in Part 2 of BS 7671 as: A current resulting from a fault of negligible impedance between a line conductor and an exposed-conductive-part or a protective conductor.

An extraneous-conductive-part is defined in Part 2 as: A conductive part liable to introduce a potential, generally Earth potential, and not forming part of the electrical installation.

In order for current to flow through a conductor, person or livestock there must be a complete circuit and there must be a voltage present to drive the current. Voltage is always relative between two points. To illustrate why protective bonding is and is not necessary, consider the following examples, which firstly explore the touch voltage developed in the event of an earth fault with simultaneously accessible extraneous-conductive-parts, and secondly, with there being a plastic insert at the entry point, as per Regulation 411.3.1.2.

Fig 2 illustrates part of an installation where an earth fault has developed and as a result a fault current (If) flows in the earth fault loop path. The type of earthing system is not important, but in this example the system is TN-C-S. Fig 2 shows a touch voltage relative to Earth at the point of the fault and any nearby simultaneously accessible extraneousconductive-part, which in this case is a metallic water pipe.

Note: A touch voltage would also exist if the simultaneously accessible part was an exposedconductive-part.

The touch voltage of Fig 2 can be found from: Ut = If × R2 where If =

Fig 3 Touch voltage between a metallic water service pipe with no protective bonding

If R1

R2

Rw Star point

0.36 Ω RPEN

Metallic (mild steel)

RPEN

0.36 Ω

Extraneous-conductive-part

The earth fault loop impedance (Zs) can be found from summating all the resistances in the loop, which in this case is 1.68 Ω.

This conforms to the maximum limiting impedance for a BS 88-2 20 A fuse given in Table 41.2(a) of BS 7671. The fault current therefore is: If =

U0 × Cmin 230 × 0.95 = 1.68 ≈ 130 A Zs

Notes: 1. In all of the following calculations, the effects of reactance have been ignored.

2. Although R2 forms a parallel connection with Rn, it is assumed that the fault has zero impedance and because of the load resistance being in series with Rn, there will be little current flow through the neutral conductor.

Scenario 1: No protective equipotential bonding

L BS 88-2 20 A

0.18 Ω

Volt meter

0.5 Ω MET

U0 × Cmin Zs

If

Ut

Point of fault

Fig 2 Earth fault loop path for a TN-C-S earthing system

0.34 Ω R1-

0.3 Ω

0.3 Ω R1

If

Ut

Rn 0.3 Ω

N If

cpc

If

Load

0.5 Ω

R2

If

Metallic (mild steel) SAFE T Y ELEC TRIC AL CO NNEC TIO N DO NOT REMO VE

MET

The touch voltage between the point of fault and the adjacent metallic cold water service, which forms a good contact with Earth, and can be considered to have negligible resistance is: Ut = If × (Rs + RPEN) = 130 × (o.5 + 0.36) Ut = 130 × (0.5 + 0.36) ≈ 112 V According to Table 1 of BS IEC 60479-1 Effects of current on human beings and livestock – Part 1: General aspects, 50% of the population have a resistance between hand-to-hand of 1 725 Ω at a touch voltage of 100 V in dry conditions.

This equates to a current flow across the heart of:

Extraneous-conductive-part

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T E C HN I CAL

Ut

I =R

body

112

= 1 725 ≈ 65 mA

Fig 4 Touch voltage with protective bonding

If

This level of fault current can lead to heart fibrillation with irreversible effects – a serious risk of death.

Scenario 2: Protective equipotential bonding connected

R1

0.3 Ω Ut

Point of fault

The touch voltage between the point of fault and the adjacent metallic cold water service with a protective equipotential bonding conductor connected is:

R2

Volt meter

0.5 Ω

Metallic (mild steel)

MET Protective bonding

SAFE T Y EL EC TR I C A L CONNEC TI O N DO NOT R EMOV E

RPEN

Ut = If × R2 = 130 × 0.5 Ut = 130 × 0.5 ≈ 65 V From Table 1 of BS IEC 60479-1, 50 % of the population have a resistance between hand-tohand of 2 000 Ω at a touch voltage of 75 V in dry conditions.

This roughly equates to a current flow across the heart of: I=

Extraneous-conductive-part

65 Ut = ≈ 33 mA Rbody 2 000

Older properties, such as those built before the 1970s, will typically have services made of metal, and as such require protective bonding. From the three scenarios, it is clear the effects bonding has on potential touch voltages in the event of an earth fault. Many utility companies are changing their main water and gas pipework to plastic, but there is no legal requirement for them to change the pipework on an individual’s property. It is incumbent upon the property owner to ensure premises have the correct bonding in place.

The protective bonding conductor has provided a parallel path to Earth and thereby lowered the resistance at the MET – the risk of death has reduced significantly.

Scenario 3: Insulating section at point of entry With the cold water service pipework being of insulating construction, there is no longer a touch voltage potential between the point of fault and the adjacent metallic pipework. The water supply pipe is no longer considered to be an extraneous-conductive-part and is unable to transmit an Earth potential.

It is therefore unnecessary to carry out protective equipotential bonding on service pipework when it is made out of insulating material such as medium density polyethylene.

It is impossible for a current to flow to Earth via water or gas pipework when there are insulating sections at the point of entry on such services.

Fig 5 No touch voltage potential between metallic pipework and fault location

If Water pipework no longer an extraneous-conductive-part R1 Ut

Point of fault

Volt meter

R2 MET

Metallic (copper)

Summary Regulation 411.3.1.2 of BS 7671 (2018) recognises that the supply pipework for water and gas to domestic premises is now likely to be made of an insulating material such as medium density polyethylene. This is non-conductive and hence is not an extraneous-conductive-part. Carrying out protective equipotential bonding on such parts is unnecessary as it cannot transmit a potential such as Earth potential. Any inclusion of a protective bonding conductor is pointless.

RPEN Stop valve

MDPE

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Companies can surely make use of this as and when staff do return to the office.

After all, most pets are likely to agree with you, so talking to the dog/cat/gerbil could make the paw-fect sounding board.

Keeping with the theme of pets, Jonathan Issac, owner of CanDo Electrics in Neath Port Talbot, has sent in these pictures of just a couple of the pets he encounters during the course of his work as a domestic electrician.

“The vast majority are friendly and some are highly inquisitive,” he says. “While customers usually offer to remove their pets, my response is so long as they don’t bite, leave them free to roam! I enjoy their company and I haven’t managed to electrocute any yet!”

Have you come across any unusual pets during your work? Email currentaffairs@ redactive.co.uk with pictures

Tell us about any hidden talents or charity initiatives. Email currentaffairs@redactive.co.uk

Bath time! Giving all the hand tools a good clean down at ProElec Electrical Services, Greater Manchester

A new addition to the team at Bark – sorry – Bard Electrical in Exeter

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Motor testing at its best MTR105 Rotating Machine Tester The new Megger Baker MTR105 hand-held static motor tester is designed for performing multifunctional tests on motors.

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15/01/2021 15:24

Connect and convert Connect with new customers and convert them into satisfied ones

Join Which? Trusted Traders Call 0117 456 6036 quoting TTNICEIC trustedtraders.which.co.uk/niceic

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15/01/2021 15:25