Essential Reading for Electrotechnical Trainees
MAGAZINE YOUR COURSE COMPANION Terms 1&2 Autumn Issue 2014 Price: £2.00
www.sparks-magazine.co.uk for news, reviews and competitions
NATION
AL
COMPET headlin
ITION ‘1
e spon
sor
ENTRY DET SEE PA AILS GE 3
IN THIS ISSUE... LEVELS 2 & 3 COURSE TOPICS COVERED WE GET READY FOR NATIONAL APPRENTICE OF THE YEAR 2015
PLUS
Candidate Name:
BUMPER
48-PAGE ISSUE!
SEE PAGE 14 FOR HELPFUL AM2 ADVICE AND JIB EXPLAIN THE IMPORTANCE OF THE ECS CARD ON PAGE 35
Course:
College:
5
Setting The Standards
for the electrotechnical industry
Once you've qualified – get your hands on one of these ECS - the competence card for the electrotechnical industry ● Proves your competence, qualifications and identity
● Shows you have been Health & Safety assessed
● Get access to construction sites
● Is the industry's CSCS card
Apply soon after your apprenticeship completion – it's easier to do it now rather than later!
www.ecscard.org.uk Visit our website or call 03333 218 230. If you’re in Scotland call 0131 445 9216 or visit www.sjib.org.uk Administered in England, Wales & Northern Ireland by the Joint Industry Board for the Electrical Contracting Industry
Administered in Scotland by the Scottish Joint Industry Board
CONTENTS
Essential Reading for Electrotechnical Trainees
MAGAZINE YOUR COURSE COMPANION Price: £2.00
Terms 1 & 2 Issue 2014
WHAT’S IN THIS ISSUE OF
www.sparks-magazine.co.uk for news, reviews and competitions
WIN! NATI
IN THIS ISSUE... APPRENTICE OF THE YEAR 2015
PLUS
08
06
sponsor
ENTRY DETAILS SEE PAG E3
LEVELS 2 & 3 COURSE TOPICS COVERED WE GET READY FOR NATIONAL
PAGE
headline
PAGE
COMPETITONAL ION ‘15
Candidate Name:
BUMPER
48-PAGE
Course:
ISSUE!
SEE PAGE 14 FOR HELPFUL AM2 ADVICE AND JIB EXPLAIN THE IMPORTANCE OF THE ECS CARD ON PAGE 35
College:
Editor
Advertising office@sng-publishing.co.uk Technical Contributor Mike Davies Electrical Engineer & Lecturer Graphic Design Studio 74 www.studio-74.co.uk
Publisher Celia Matthews celia@sng-publishing.co.uk
Printers Woodford Litho Ltd England General Enquiries SNG Publishing Ltd Chiltern House, 45 Station Rd Henley-on-Thames RG9 1AT 0870 774 3049 www.sparks-magazine.co.uk To subscribe to SPARKS Magazine call 0870 774 3049 or subscribe online at www.sparks-magazine.co.uk
PAGE
Carlie Cohen editor@sng-publishing.co.uk
03
>>
SYLLABUS
>>
FEATURES
04
SPOT THE MISTAKE
10
SAFE ISOLATION OF POWER SUPPLIES
03
NATIONAL APPRENTICE OF THE YEAR 2015 GETS UNDERWAY
13
RECOMMENDED SEQUENCE OF SAFE ISOLATION FOR SINGLE-PHASE SUPPLIES
06
JOBS FOR THE GIRLS CAMPAIGN
16
MATCHING UNITS AND SYMBOLS
08
ELECTRONICS LINE 3000 COMPETITION TO
14
22
HAND TOOLS
AM2 ADVICE FROM NET
20
24
ELECTRIC CERTIFICATION
HELLERMANNTYTON APPRENTICE INTERVIEW
26
CONNECTING ELECTRICAL MEASURING INSTRUMENTS
21
RIDGID EXPLAIN THE BENEFITS OF THEIR MULTI-FUNCTIONAL RE 60 ELECTRICAL TOOL
28
SELECTING DATA USING THE IET ON-SITE GUIDE
35
32
THE PRINCIPLES OF ELECTRICITY SUPPLY
JIB DISCUSS THE IMPORTANCE OF THE ECS CARD
PYTHAGORAS THEOREM OF RIGHT-ANGLED TRIANGLES
42
EXAM PREPARATION ADVICE
36 38
VOLTAGE DROP IN FINAL & DISTRIBUTION CIRCUITS
>>
REGULARS
40
TRANSPOSING FORMULAE
02 49
NEWS PRODUCTS & SERVICES
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WIN A COMMPACT INTRUSION SYSTEM
Note from the Summer holidays are over – time for the start of a fantastic new academic year and all the opportunities that it can bring. This issue, have a look at some helpful ideas if you’re considering entering our National Apprentice of the Year competition plus some great exercises created to help support you in your syllabus.
And finally, don’t forget to keep your eye on Facebook each Friday for the Sparks Freebie Friday competition. Get your hands on some superb free prizes – like us on www.facebook.com/ sparksmag and follow us on Twitter @ sparksmagazine to make sure that you don’t miss out!
Carlie Cohen Editor
Lecturers and students can find the answers to exercises by visiting and the SPARKS website, www.sparks-magazine.co.uk
© SNG Publishing Ltd, 2014
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twitter.com/sparksmagazine SPARKS Magazine / 1
INDUSTRY NEWS ESR WELCOME LAUNCH OF REGISTERED COMPETENT PERSON DOMINO’S SUPPORTS ITS LONE WORKERS Domino’s is using the marketleading Identicom device as part of a health and safety initiative to protect staff working alone. Designed to look and feel like a standard identity card and is wearable, ensuring it is close to hand and discreet to use. It offers protection by helping workers to capture verbal abuse and raise an alarm; helping managers to meet their duty of care. Visit www.SoloProtect.com
INDUSTRY
The Electrical Safety Roundtable (ESR) has welcomed the launch of a new search facility and mark – designed to provide a single point of reference for consumers looking for an electrician – as an important milestone for the electrical industry. The industry group, which includes participants from the Chief Fire Officers Association, City & Guilds, Local Authority Building Control, the NAPIT Trade Association and other influential stakeholders, has been an outspoken supporter of the need to raise consumer awareness and the importance of using a registered, competent electrician since their initial Westminster meeting in June 2012. Chair of the Roundtable Chris Bielby MBE comments, “Choosing a registered, competent electrician remains the simplest and also one of the most effective ways of ensuring electrical safety in the home.” For more info visit: www.electricalsafetyroundtable.co.uk or www.electricalcompetentperson.co.uk
NEWS Read the full story in the news section of www.sparks-magazine.co.uk
NEW BASEC LAB FACILITIES TO MEET DEMAND FOR CPR FIRE TESTS
MEGGER MULTIFUNCTION TESTERS GET DOWN TO EARTH In response to the growing need for earth electrode resistance measurements, Megger has added a new model to its popular and successful MFT1700 family of multifunction installation testers. When used in conjunction with the appropriate accessories, the new MFT1735 provides comprehensive facilities for two-pole, three-pole, stakeless and ART earth electrode resistance measurements, as well as all the functionality needed to test electrical installations in line with the 17th Edition of the IET Wiring Regulations. For more info visit: www.uk.megger.com
2 / SPARKS Magazine
The British Approvals Service for Cables (BASEC) is anticipating a strong demand for their soon to open cable fire testing facility, as the cable industry moves to implement the Construction Products Regulation 2011 (CPR). Their new test laboratories at BASEC’s headquarters in Milton Keynes are into their commissioning phase and will go fully live by the end of this year. Three new re-configurable fire test labs and a ladder rack rig, join BASEC’s existing smoke and halogen testing facilities which form part of the largest dedicated testing facility in Europe. The facilities also include a 3 cubic metre smoke chamber for smoke emission tests (EN 61034-2). For more info visit: www.basec.org.uk
NEWEY & EYRE WIRES INTO DIGITAL DEMAND With the increasing demand of digital, Newey & Eyre has announced the launch of its innovative Newlec double 13A switched socket with twin USB chargers. Featuring two 5V USB chargers with up to 2.1 amps, which are suitable for charging a full scope of digital devices including iPads, iPhones, tablets, mobiles and cameras. The sockets fit to a standard wall patress, with no modifications to size or wiring required, so installation is quick and easy for the contractor. They are also supplied with an optional 10mm spacer for 25mm box retrofits and come with a 30-year guarantee. For more info visit: www.neweysonline.co.uk
NATIONAL COMPETITION
BE IN IT TO WIN IT! If you’ve the ambition to be recognised for your outstanding skills, little can beat the pride and glory experienced by the winners of the Megger National Apprentice of the Year competition. In its sixth year, the 2015 event is set to be the toughest yet; recognising the cream of the industry’s apprentices across the UK.
What are you waiting for? Testing your skills, helping to build your confidence and prepare for the workplace, it’s your chance to show potential employers your strengths in commitment and determination. Add to your skills the impressive award-winning status of the Sparks National Apprentice of the Year and encourage potential employers to consider you as a valuable recruit.
Introducing our sponsors Welcome and thank you: GOLD SPONSOR
Silver Sponsor
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in association with
Congratulations to our 2014 winner Luke Mayor of Cardiff & Vale College.
Comments from the competition’s founder
WINNE R 2014
Celia Matthews, founder of the National Apprentice of the Year competitions and publisher of SPARKS Magazine, comments, “We’re really looking forward to seeing this year’s entrants and have fantastic support from some of the industry’s leading and most innovative manufacturers. Make this your year and enter!”
HOW DOES IT WORK? Each college may enter one NVQ Level 2 or 3 student – whether industry or college-based. Every competitor will be invited to attend one of six regional heats with an overall regional winner chosen. In successfully completing the practical competition you’ll receive a Certificate of Achievement and tools. The entry deadline is Friday 28th November 2014. For further information, contact Celia Matthews on celia@sng-publishing.co.uk or 01491 845386. Keep up to date with the progress of the competition by visiting www.sparks-magazine.co.uk
SPARKS Magazine / 3
EXERCISE
SPOT THE MISTAKE Are you considering entering next year’s Apprentice of the Year? With the level of competition being as fierce as this year’s, it’s certainly worth ensuring that you don’t lose out on the small details.
1 Have a look at the photos here and see if you can spot some of the problems that we spotted this year. If you can’t spot the errors, have a look online for the answers at:
www.sparks-magazine.co.uk
2
3
Go to www.sparks-magazine.co.uk to freely download exercise answers 4 / SPARKS Magazine
EXERCISE
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Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 5
FEATURE
JOBS FOR THE GIRLS In 2007 women made up just one per cent of all Electrotechnical apprentice starts. Fast forward seven years and that figure is still not much better. However, the sight of a female apprentice training to be an electrician is perhaps not as strange as it might once have been.
Attitudes are changing Evidence from leading certification body NICEIC suggests that in recent years there has been a huge steer from young women looking to take on a trade over a profession. This change in attitudes has been attributed to the increasing costs associated with going to college or university. In a bid not to incur such costs many women are looking to learn a trade as an alternative career. Indeed recent research reveals that learning to become an electrician is the number one choice of trade for women aged between 16– 24.
6 / SPARKS Magazine
While the cost of going to university is no doubt a contributory factor to this change in attitude, learning a trade also means women can develop a skill which will be with them in life, allow them to work on their own or within a team, and more importantly allow them flexible working hours to work round home or family commitments. “Perceptions of the industry are definitely changing,” commented NICEIC CEO Emma Clancy. “Electrical work is a lot more light intensive now and the physicality of the work is not an issue. Employers are also a lot more geared up to their responsibilities and provide suitable conditions for both sexes on site. “For women - either at school leaving age or later in life - learning a trade is definitely becoming a viable alternative to taking up an office based profession.” For NICEIC this change in attitude is particularly pleasing. In 2011 it set up its Jobs for the Girls campaign to encourage more women into the industry and redress the imbalance.
The objectives of the campaign were clear from the onset: To Inspire more women to seek a career as an electrician Promote the benefits of employing female electricians Challenge prejudices of a ‘male only’ profession Highlight the opportunities and benefits a career as an electrician
FEATURE Support for the campaign The campaign has proved hugely successful. NICEIC have been invited to Westminster to speak with government ministers about the issue, successfully challenged sexist adverts in the media and gained support from key organisations such as JTL, IET (Institute of Engineering and Technology), ECA (Electrical Contractors’ Association) and WAMT (Women in Manual Trades). Last year TV star Hilary Devey also gave her support to the campaign in a series of radio and TV interviews. This year NICEIC set up academy for those women just starting out in the industry.
“This is evidence that attitudes are changing. The job of an electrician is no longer seen as traditionally ‘mans work and that is definitely something we wanted to achieve when we started this campaign.”
“When we started the jobs for the Girls campaign – it was actually quite difficult to find women working in the industry who could act as ambassadors or role-models,” added Emma. “However, we now have a network of around 100 women who have come forward and shown us that there is a very real interest from women to not only join the industry, but who are out there showing how it can be done.
Whilst more and more women are now coming forward expressing an interest in becoming an electrician, the longer term goal of seeing more women out on the job will take time to record due to the length of training involved.
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But for now the sight of more women on apprenticeship courses or out on site with a screwdriver in hand is encouraging. As Emma concludes: “As a woman in a senior position within the electrical contracting industry I feel I have a responsibility to contribute to its growth and development in a tangible way. “I love my job and have enjoyed a great career in the electrical world and want others to see the excellent opportunities available.” For more information about the jobs for the girls campaign log on to www.jobsforthegirls.com
COMPETITION
WIN A COMMPACT INTRUSION SYSTEM FROM ELECTRONICS LINE 3000 WORDSEARCH – Inspection and Testing Try to find the following words that are all related to the inspection and testing process. (Answers can be across, up, down or diagonal) Its streamlined, space-saving design also offers a professional, highly reliable system at a competitive price. Connected to the Cloud-based ELAS server, it can be controlled remotely by EL’s smartphone app; enabling users to arm / disarm the system remotely as Visual Meter Insulation well as receive email / SMS / voice notificationsLoop and view and store a history of events. Electrode Protective Main Fault Phase Rotation Earthing Test To win this great prize, try to find the words listed below that are related to the inspection Bonding Label Inspection Certificate and testing process. Answers can be across, up,Prove down or diagonal. One word is repeated. Probe Safety Disconnection Which one is it? Note: one word is repeated, which one is it? A
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Answer: the repeated word is:
ANSWER: The repeated word is
To enter, email the repeated word, along with your name and contact details to editor@sng-publishing.co.uk, marking the subject title as ‘CommPact Competition’. Closing date: 28th November 2014. The winner will be announced in the next issue.
8 / SPARKS Magazine
WIN! W IN! WIN!
EXERCISE
SAFE ISOLATION OF POWER SUPPLIES Covering Outcome 1 of Unit 307 (or EAL equivalent) ‘Understand Principles, Practices and Legislation for the Inspection, Testing, Commissioning and Certification of Electro-Technical Systems and Equipment in Buildings, Structures and the Environment’. (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91)
Regulation 14 of the Electricity at Work Regulations 1989 clearly states that ‘no person shall be engaged in any work activity on or so near to any live conductor…’ (There are certain conditions, that if met, permit work to be undertaken – see the HSE Memorandum of guidance on the EAWR 1989) The safe isolation of the power supply prior to commencing work on a circuit, on groups of circuits or on permanently connected electrical equipment, must always be considered first.
CHECK YOUR KNOWLEDGE Q1. List the HSE recommended test equipment that will be needed before safe isolation can be carried out?
Q2. State the precaution/s that need to be considered before isolating any electrical circuit, groups of circuits or electrical equipment?
Go to www.sparks-magazine.co.uk to freely download exercise answers 10 / SPARKS Magazine
EXERCISE Q3. Briefly explain the recommended procedure for isolating a circuit or groups of electrical circuits.
The basic principle of safe isolation is that the point of isolation is under the control of the person who is carrying out the work on the isolated conductors.
Q4. Identify all of the possible means of isolation for a final circuit.
All personnel involved in work on electrical systems and equipment must be competent and, where necessary, be suitably instructed on safe systems of work. Personnel should be provided with written instructions, and have access to, appropriate locking-off devices, warning notices, a voltage detector and proving unit.
Permit-to-work The permit-to-work system must be applied to work on high voltage (HV) systems that have been made ‘dead’ and for certain low voltage (LV) work such as the case when more than one person will be working on the isolated circuit.
A Permit is a statement that a circuit or item of equipment has been safely isolated and it is therefore safe for work to commence.
NOTE: Permits should not be used for live working as this can cause confusion and possible danger. Further information regarding permits, are given in the HSE document HSG85. In some situations it may be necessary to provide a Method Statement detailing the activities that are to take place, including safe isolation.
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 11
EXERCISE Q5. Write a method statement for the safe isolation procedure from the point of securely isolating the circuit.
DID YOU KNOW Most leading agencies provide step-by-step guidance for carrying out safe-isolation. It will be helpful to explore the guidance by looking at websites. The HSE provide comprehensive information regarding electricity at work and the precautions that need to be taken when working on or near live conductors. See www.hse.gov.uk
Go to www.sparks-magazine.co.uk to freely download exercise answers 12 / SPARKS Magazine
EXERCISE
A RECOMMENDED SEQUENCE OF SAFE ISOLATION FOR SINGLE-PHASE SUPPLIES To ensure that RCDs and RCBOs do not trip when connecting an approved - voltage tester to circuits that may not be isolated, the following sequence of test probe connections is recommended.
NOTE: Always make probe contact with neutral before line otherwise one probe will be live.
STEP 1
STEP 2
Neutral
Line
1st contact neutral
2nd contact line
Neutral
Line
Leave probe on neutral
STEP 3
Neutral
Earth
NOTE: Providing that Step 1 proves dead then it is assumed safe to check to earth without tripping RCDs or RCBOs.
Earth
3rd contact earth
Line
Earth
4th contact line
Leave probe on earth
NOTE: If you are training to become a qualified electrician or other competent trades person it is essential that you practice this procedure under the guidance of a supervisor.
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 13
FEATURE
ADVICE FOR AM2 The AM2 is the final practical assessment of the electrical apprenticeship – using the official checklist could help you pass. No doubt if you’re reaching the end of your apprenticeship, you’re a little apprehensive about your AM2 - the final assessment you’ll need to become a fully qualified electrician. Don’t panic! You’ve spent years training. The AM2 is intended to assess only those competencies you should already have acquired during your apprenticeship. You’re already in the driving seat and in no time at all you could be fully qualified. Run by National Electrotechnical Training (NET), AM2 is an appropriate assessment of your skills; giving you the tools to make sure you know you’re ready for it. You’ll also stand a much better chance of passing first time.
I’ve filled in the checklist and I’m good to go. Now what? Even the most experienced electricians might make mistakes - don’t sit back and relax just yet! While you might have done all the training required to pass the AM2, there’s a difference between knowing how to do it and actually doing it. Use the Checklist as your revision guide – go through the list with your employer and training provider, work out which tasks you’re not quite so strong on, and practice them until you’re feeling much more confident. Don’t forget, you’re also by no means the first to do an AM2, and those who haven’t passed tend to make the same mistakes. Take a look at NET’s AM2 Common Candidate Errors Guide. This will show you where the majority of mistakes happen.
What’s actually in the AM2? The assessment is broken down into four sections typically over three days: SECTION A AND A1: Risk Assessment and Safe Isolation (1 hour); Composite Installation (8.5 hours) SECTION B: Inspection and Testing of the completed composite installation (3.5 hours) SECTION C – C1: Safe Isolation (30 minutes) and €C2 Fault Diagnosis and Correction (2 hours) SECTION D: Assessment of Applied Knowledge (1 hour) For more information, visit the NET website.
I’m feeling pretty confident now – am I ready?
So what should I do? Firstly, visit the NET website (www.netservices.org.uk) and the AM2 Self-Assessment Checklist. A compulsory bit of paperwork well worth the time it takes to fill it in!
The Checklist will show you everything you should have learned before going into the AM2. Read through it and check you have done it all! It’s your employer’s and trainer’s responsibility to make sure you’ve covered everything on the list, so they should go through this with you and help identify any areas of concern.
14 / SPARKS Magazine
Almost! Don’t forget the theory element of the AM2. You’ll need to be up to speed on four different guides: the Building Regulations (not just Part P, but any of the regulations that might impact on electrical installation work!), the current edition of the Wiring Regulations (BS7671), the On-Site Guide and the IET Guidance Note 3. Revise these carefully – you don’t want to spend three days in the AM2 test rig getting everything right, only to end up losing points on the theory aspects. Then there’s just three final pieces of paperwork left. Make sure you’re confident in completing an IET Electrical Installation Certificate, and that your measured results conform to the requirements of BS7671. Also make sure you’re confident about completing a Schedule of Inspections and Schedule of Test Results, and carrying out all the necessary tests for these. All being well, you’ll pass and ready to work as a fully qualified, safe and competent electrician. Good luck!
ON THE DAY... Get a good night’s sleep the night before your first assessment day and during the three day assessment period – don’t make big plans for the evenings! Bring in your filled-in Checklist Know exactly where the test centre is and how to get there. Leave enough time to travel; you don’t want to be late. Don’t panic!
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EXERCISE
MATCHING UNITS AND SYMBOLS Covering Unit 309 (or EAL equivalent) ‘Understand the Electrical Principles Associated with the Design, Building, Installation and Maintenance of Electrical Equipment and Systems’. (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) The following terms all relate to electrical Units and Symbols. Try to match the symbol with the definition.
UNIT NAME
UNIT SYMBOL
1
Kilogram
A
W
2
Candela
B
F
3
Weber
C
Hz
4
Watt
D
Cd
5
Farad
E
T
6
Joule
F
C
7
Tesla
G
kg
8
Hertz
H
H
9
Coulomb
I
J
10
Henry
J
Wb
CHECK
CHECK
1=
6=
2=
7=
3=
8=
4=
9=
5=
10 = Go to www.sparks-magazine.co.uk to freely download exercise answers
16 / SPARKS Magazine
EXERCISE
MATCHING UNITS AND SYMBOLS Covering Unit 309 (or EAL equivalent) ‘Understand the Electrical Principles Associated with the Design, Building, Installation and Maintenance of Electrical Equipment and Systems’. (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) The following terms all relate to the quantities and units used in electrical engineering. Try to identify the correct quantity for each unit given.
UNIT NAME OR SYMBOL
QUANTITY
1
X
A
Impedance
2
E
B
Magnetic field strength
3
Weber
C
Reactance
4
L
D
Resistivity
5
Coulomb
E
Electric field strength
6
H
F
Magnetic flux
7
Z
G
Charge
8
Rho
H
Self - inductance
9
Candela
I
Weight
10
G
J
Luminous intensity
CHECK
CHECK
1=
6=
2=
7=
3=
8=
4=
9=
5=
10 = Go to www.sparks-magazine.co.uk to freely download exercise answers
18 / SPARKS Magazine
www.hitachi-powertools.co.uk
INTERVIEW
APPRENTICE INTERVIEW SPARKS Magazine interviews HellermannTyton’s new recruit. TONY: I’ve had the opportunity to learn about injection moulding, materials and plastic manufacture plus spatial awareness. SPARKS: What do you enjoy most about your job? TONY: It’s definitely been working closely with customers and meeting larger companies. I particularly enjoy building my client base and meeting lots of people. SPARKS: What has been the most challenging part of your new job? TONY: Nothing really. It’s a completely different lifestyle from university – so if anything it’s been the change of lifestyle and settling down. SPARKS: How do you think your new job will help progress your career?
FULL NAME: Tony Doyle
SPARKS: Congratulations on your new job role! Which course did you study? TONY: BA (Hons) Industrial Design SPARKS: Which College or Uni did you go to?: TONY: Northumbria University SPARKS: Lecturer’s name? TONY: We had lots of lecturers on the course; however the senior leading lecturer was Howard Fenwick. SPARKS: How long have you been working for HellermannTyton? TONY: I’ve been here for ten months. SPARKS: How did you hear about the vacancy? TONY: Through my final year tutor.
AGE: 23
TONY: Not really. I was fairly prepared for the interview and answered all of their questions. SPARKS: What impressed you most about this job? TONY: It’s the diversity of the work involved. It’s not just design but project management as well. SPARKS: What advice would you give someone who is leaving college / uni and trying to find work? TONY: Go and find as much work experience as you can. Even if it’s unpaid as it will help you in your search for work. SPARKS: What other jobs have you done in the past?
TONY: Yes, I was.
TONY: I’ve worked at a variety of places, including in bars plus other customer satisfaction roles. I’ve also had freelance design office placements.
SPARKS: Did they ask you any questions that you weren’t prepared for?
SPARKS: What do you think you have learnt since working for HellermannTyton?
SPARKS: Were you nervous when you went to the interview?
20 / SPARKS Magazine
TONY: I think it will be a good basis for a designer to discover how something is made – understanding the final processes first will help me develop my skills. SPARKS: What’s your ambition for the future? TONY: I’m looking to be some kind of creative director of a large firm and certainly to be recognised for my work.
QUICK FIRE Q & As… What did you have for breakfast this morning? Fruit, yoghurt and coffee What’s your favourite film? Shawshank Redemption If you could have dinner with a celebrity who would it be? Not alive now, but Frank Sinatra If you could be anyone in history who would it be? Muhammad Ali Who’s your favourite band? Kings of Leon What’s your favourite football / rugby team? Middlesborough FC
FEATURE
RE 60 ELECTRICAL TOOL FEATURES
3-IN-1 QUICKCHANGE SYSTEM™ FOR CUTTING, CRIMPING AND PUNCHING Innovative new tool offers interchangeable heads for speed and efficiency.
RE 60 electrical tool
The revolutionary new tool offers a 3-in-1 solution for cutting wires, crimping lugs and punching electrical boxes all with a single tool. The RE 60 Electrical Tool, featuring the unique RIDGID QuickChange System™, incorporates a moveable collar that lets contractors quickly and easily switch between three interchangeable heads with 360° rotation: the SC-60B Scissor Cutter Head; the LR-60B Latching Round Crimp Head and the PH-60B Punching Head. As a result, there’s no longer a need to carry multiple, dedicated tools to the jobsite or completely switch from one tool to the next, which increases efficiency and maximises productivity. “The RE 60 is going to be a real game changer for electrical contractors looking to save time, save money and reduce the total amount of tools they carry around,” said Enver Celik, Product Manager at RIDGID. “Just imagine cutting armoured cables, crimping lugs and punching access holes with a single tool. It’s all possible now with the RE 60.”
The new RE 60 Electrical Tool from RIDGID cuts wire, crimps lugs and punches boxes with the use of the unique RIDGID QuickChange System. Featuring an inline design for easy, one-handed operation, the RE 60 provides a 60 kN hydraulic force output to cut armoured cables up to 50 mm OD, crimp lugs up to 300 mm² and punch round holes in boxes up to 63,5 mm OD. It also includes on-board diagnostics, LED indicators and automatic ram retraction to ensure superior performance.
Interchangeable heads The SC-60B Scissor Cutter Head allows electrical contractors to cut numerous types of armoured aluminium or copper cable without having to switch heads or buy numerous tools. It features interchangeable blades for cutting up to 50 mm OD copper / aluminium building wire or 50 mm OD copper fine stranded wire. The LR-60B Latching Round Head quickly crimps cable lugs up to 300mm² cable. And, thanks to its slim design and ergonomic latching system, it allows for work in tighter spaces. The PH-60B Hole Punching Head punches round holes up to 63,5 mm in 3 mm mild steel and is compatible with punch dies from RIDGID and other manufacturers.
For further information check out www.ridgid.com
SPARKS Magazine / 21
EXERCISE
HAND TOOLS Covering Outcome 5, Sub-Section 3 of Unit 305 (or EAL equivalent) ‘Understand the Practices and Procedures for the Preparation and Installation of Wiring Systems and Electro-Technical Equipment in Buildings, Structures and the Environment.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) The electrician will need to use, and look after, a range of hand tools in order to carry-out his / her duties. Apart from the generally accepted hand-tools such and pliers, screwdrivers and stripping knife, an electrician will also need a hacksaw, engineers square and a range of files. The following tasks all refer to files - the various types available and the care needed to ensure they last you a long time.
FILES Q1. Describe the purpose of a file.
If for example the cut edge of a section of steel trunking is uneven a flat file can be used to remove unwanted metal and thereby make the edge level or straight.
Trunking not cut straight
Excess metal can be removed with a flat file
TYPES OF FILES Q2. Identify each of the following files. a)
b)
c)
d)
e)
f)
The cutting ‘teeth’ of a file can be formed in various ways: Rough or Bastard files have very course teeth that are cut across each other and are designed to remove large quantities of material. Second Cut files have teeth cut one way only and are designed to cut equal layers of material with the result the finish is generally smoother than that of the rough cut file. A Smooth file will have teeth cut at a smaller depth than the other files mentioned above, the resulting cut is a smooth fine finish to the work-piece.
Go to www.sparks-magazine.co.uk to freely download exercise answers 22 / SPARKS Magazine
EXERCISE CARE OF FILES Q3. State how a file may be damaged.
Q4. How can file teeth become damaged?
Q5. Explain how a file can be cleaned and any precautions that must be taken.
Q6. Suggest three safety observations to be adopted when using files.
FINAL NOTE: Always discard used files sensibly, if possible recycle the metal.
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 23
EXERCISE
ELECTRIC CERTIFICATION Covering Outcome 5 of Unit 307 (or EAL equivalent) ‘Understand Principles, Practices and Legislation for the Inspection, Testing, Commissioning and Certification of Electro-Technical Systems and Equipment in Buildings, Structures and the Environment.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) THE MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE Q1. State the purpose of the Minor Electrical Installation Works Certificate.
The ‘certificate’ is a single sided A4 pro-forma on which all the necessary details relating to the minor electrical installation work are stated.
Q2. State two persons that need to retain copies of the Minor Electrical Installation Works Certificate when work has been completed.
Q3. The following task requires you to study the installation details and complete a copy of the Minor Electrical Installation Works Certificate.
INSTALLATION DETAILS SET 1: You have installed a fused-connection unit, (fused spur) on an existing 32A rated ring-final circuit at ABC stores, 243 Widecombe Place, Belchester, DN0 4EX on 1st April 2014. The original ring circuit was installed five years ago and looks in good condition as does the rest of the electrical installation in the store. The supply system is TN-S and fault protection is by ADS. The existing ring circuit is protected by a 32A Type B circuit-breaker to BS EN60898 and additional protection is provided by a 30mA RCD, the addition of the fused-connection unit will not compromise the current rating of the existing ring-final circuit. No previous test results are available to compare with the test results obtained when the addition was completed. The ‘new’ test results are all within the expected range. Continuity of circuit protective conductor and main protective bonding conductor is 0.1Ω and 0.5Ω respectively; insulation resistance between all conductors is +200MΩ; polarity was confirmed; earth fault loop impedance is 1.10Ω and the RCD reaction time test proved satisfactory with the I∆n at 25mS. The main water service is bonded with 10mm 2 single-sheathed earth cable.
Go to www.sparks-magazine.co.uk to freely download exercise answers 24 / SPARKS Magazine
EXERCISE
MINOR ELECTRICAL INSTALLATION WORKS CERTIFICATE To be used for minor electrical installation work that does not include new circuits.
PART 1: Description of minor works 1. Description of minor works 2. Location / Address 3. Date minor works completed 4. Details of departures, if any from BS7671:2008
PART 2: Installation details 1. System earthing arrangement
TN-C-S
TN-S
TT
2. Method of fault protection 3. Protective device for the modified circuit
Type
Rating
Comments on existing installation, including adequacy of earthing and bonding arrangements
PART 3: Essential tests Earth continuity satisfactory Insulation resistance: Line / neutral
MΩ
Line / earth
MΩ
Neutral / earth
MΩ
Earth loop impedance
Ω
Polarity satisfactory RCD operation (if applicable). Rated residual operating current I∆n
mA operating time of
ms at I∆n
PART 4: Declaration I / we CERTIFY that the said works do not impair the safety of the existing installation, that the said works have been designed, constructed , inspected and tested in accordance with BS7671:2008, amended to , and that the said works, to the best of my / our knowledge and belief, at the time of my / our inspection complies with BS7671 except as detailed in Part 1 above.
Name:
Signature:
For and on behalf of:
Position:
Address:
Date:
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 25
EXERCISE
CONNECTING ELECTRICAL MEASURING INSTRUMENTS Covering Unit 309 Outcome 7 (or EAL equivalent) ‘Understand how Different Electrical Properties can affect Electrical Circuits, Systems and Equipment’. (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) Understanding the type and use of various electrical test instruments is important because incorrect connection can seriously damage the instrument, the circuit in which it is connected and could pose a danger to the operator. The following tasks relate to the measuring or determination of power in single-phase a.c. circuits.
Q1. Identify the correct name for each of the instruments identified in the circuit diagram below. L 2
3
1
N
KEY: 1)
2)
3)
Q2. State the purpose in measuring the electrical quantities at the points shown in the circuit.
Q3. Calculate the power rating (W) of an inductive load if the power factor is 0.85, the current is 50A and the voltage is 230V.
Go to www.sparks-magazine.co.uk to freely download exercise answers 26 / SPARKS Magazine
QUICK TEST
TEST YOUR KNOWLEDGE MATCH THE DEFINITION In the following exercise try to match the word to the definition
1
Temperature of the air where electrical equipment is to be used
A
Electrical installation
2
A protective conductor providing equipotential bonding
B
Obstacle
3
A plot of ground intended to be occupied by a leisure accommodation vehicle
C
Minor works
4
Equipment in which protection against electric shock does not rely on basic insulation only
D
Ambient Temperature
5
Equipment that converts electrical energy into another form of energy
E
Double insulation
6
Insulation comprising both basic and supplementary insulation
F
Class II equipment
7
An assembly of associated electrical equipment having co-ordinated characteristics to fulfil a specific purpose
G
Fuse carrier
8
The moveable part of a fuse designed to carry a fuse link
H
Bonding conductor
9
Additions or alterations to an existing electrical installation that does not include a new circuit
I
Current – using equipment
A part designed to prevent unintentional contact with live parts
J
Caravan pitch
10
1=
6=
2=
7=
3=
8=
4=
9=
5=
10 =
Go to www.sparks-magazine.co.uk to freely download exercise answers
SPARKS Magazine / 27
EXERCISE
SELECTING DATA USING THE IET ON-SITE GUIDE Covering Outcome 3 of Unit 304 (or EAL equivalent) ‘Understand Principles for Selecting Cables and Circuit Protective Devices.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) The following tasks will require reference to Appendix F of the IET On-Site Guide: BS7671:2008 +A1 2011. The main objective of this exercise is to locate and use technical information in preparation for, and in the calculation of, suitable circuit cable sizes. For each answer, indicate the table reference and column that is applicable.
Q1. A 90°C thermosetting PVC insulated cable is to be installed in an ambient temperature of 35°C, what is the rating factor for this cable?
Q2. A non-sheathed mineral insulated cable is to be installed in a location where it cannot be touched and the temperature is expected to reach 40°C, state the rating factor applicable to this cable.
Q3. A new multi-core cable is to be supported on a vertical cable tray with 6 other multi-core cables. What is the rating factor to be applied to the new cable?
Go to www.sparks-magazine.co.uk to freely download exercise answers 28 / SPARKS Magazine
EXERCISE Q4. A new single-phase circuit is to be installed to method B in an existing steel trunking. The new circuit is to be installed with 7 other single-phase circuits. What is the rating factor to be applied to the new circuit?
Q5. A three-phase circuit uses single-core insulated cable enclosed in conduit on a wall. The cable is expected to carry a current of no more than 55A, what cable size, (i.e. cross-sectional-area), is needed?
Q6. A single-phase 70mm2 single core 70째C thermoplastic insulted cable is enclosed in steel conduit on a thermally insulated wall, what is the maximum current rating for this cable?
Q7. A multi-core cable with thermosetting insulation has a cross-sectional-area of 35mm2 and supplies a single-phase circuit. What is the voltage drop per ampere per metre, (mV/A/m) for this cable?
Go to www.sparks-magazine.co.uk to freely download exercise answers Continued on page 30
SPARKS Magazine / 29
EXERCISE Q8. An insulated and sheathed flat cable 10mm2 is to be installed to Method C, i.e. clipped direct to a surface. What is the maximum current rating of this cable, and the mV/A/m?
Q9. An insulated and sheathed flat cable carries 25A for a length of 50m. If the cable is 6mm2 what is the total voltage drop for this cable?
Q10.
A single-phase multi-core thermosetting pvc insulated cable is to be installed with 3 other circuits in a conduit. The conduit is to pass through an area where the ambient temperature is likely to be 35째C. If the rating of the protective device is 32A what is the tabulated current rating of the cable when the rating factors are applied?
FINAL NOTE: Always check your selection of data and your calculations
Go to www.sparks-magazine.co.uk to freely download exercise answers 30 / SPARKS Magazine
QUICK TEST
TEST YOUR KNOWLEDGE WORDSEARCH – Health & Safety
Try to locate the following words, which relate to health & safety. You will find them horizontal, vertical or diagonal. HEALTH & SAFETY HELMET GOGGLES Try to PROTECTION locate the following words, which relateVISOR to health BOOTS & safety. CLOTHING GLOVES REGULATIONS RIDDOR ASBESTOS You willASSESSMENT find them horizontal, vertical or diagonal. ECZEMA BARRIER RISK TOXINS
B
I
P
U
Y
T
A
V N A A
S
M
P
P
T
O
X
I
N
S
Z
I
J
M Q
Y A W D
L
R
I
R
H M C
C
A
B
G D
S
S
G
C
O D A N O
F
O
L
I
A
D
E
C
R
C
K O
A
O
E
A Q T
N
B
G
B
I
S
T
C
O
I
A R
R
E
R
Z
O
L
E
B
O
U
M H
K
K
Z
C
D G F
C
N
R
A
L
C
A G G
A
E
Y
G
C
O
E
V
D A G
L
E
C
B
T
S
L G O
Z
L
C
P
F
D M X O
E D O D
V
I
H
Y
L
E M G
J
E
E
L
M A
L G T
E
O
D
C
E
G H A
B
T
N
L
A
P
D O A
E
T H N
B
O
S
A
F
C
S
Z
B
D
L
R
E
G U
L
A T
I
O
N
S
A
F
E G
S
G
F
A
E
F
A
L
E
P D N
I
O
B
I
M K A
J
C
H
I
S
M
I
U G W E
E G O
C
R
N
S
A
M R
B
J
S
B
Q D Y
G
K
F
E
C
L
H
A
S
O
I
V
R
D
R
R
S
S
G
E
S
G O I
B
I
D H R
S
W U A
E
D R
J
A
I
G A
S
E
S
S
M E
N
T
I
R
E
H
S
V
A
C O D
R
X
G A
F
G R
G
B
E
M R
G
T
O
T H E
R
M A
L
N
I
O G
L
J
S
G
V D O O
Q
P
H
D A
E
S O
S
B
M
E
R
I
N
K
Z
E
S A D
B
U
C
R
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T G
F
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S
M
J
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N
S
B
X
E
L
S
F
K
X
T
S
I C
E
J
K
ASBESTOS
ECZEMA
REGULATIONS
ASSESSMENT
GLOVES
RIDDOR
BARRIER
GOGGLES
RISK
BOOTS
HELMET
TOXINS
CLOTHING
PROTECTION
VISOR
Go to www.sparks-magazine.co.uk to freely download exercise answers
SPARKS Magazine / 31
EXERCISE
THE PRINCIPLES OF ELECTRICITY SUPPLY Covering Unit 309 (or EAL equivalent) ‘Understand the Electrical Principles Associated with the Design, Building, Installation and Maintenance of Electrical Equipment and Systems.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) Try these multiple-choice questions.
Q1
Which one of the following is a Transmission voltage?
a
230V
b
400V
c
11kV
d
400kV
The inductive reactance of an inductor Q2 rated at 0.55H, when connected to a 50Hz supply will be?
Ans.
Ans.
Q6
Electrical energy is measured using a
a
kWh meter
b
Watt meter
c
Ammeter
d
Voltmeter
Q7
The efficiency of a transformer that has an output of 10kVA at 0.8pf, and losses of 450W will be?
a
200Ω
a
80.5%
b
172.8Ω
b
89.5%
c
157Ω
c
90.5%
d
86.4Ω
d
95.5%
Three fixed resistors of 60Ω each are
Q3 connected in parallel with each other, the combined resistance is
Ans.
Q8
180Ω
b
90Ω
a
240 lux
c
60Ω
b
240 lumen
d
20Ω
c
1200 lux
d
1200 lumen
The procedure to reverse the direction of Ans. a single-phase capacitor start motor is to
a
Reverse connect line and neutral to the motor
b
Reverse the connection of the start and run winding
c
Reverse the connection of the run winding only
d
Reverse the connection of the capacitor
A six pole AC induction motor is connected to a three-phase supply of Q5 50Hz. The synchronous speed of the stator flux is
Ans.
Q9
In lighting the abbreviation MCF is which type of lamp?
a
High pressure metal halide
b
Low pressure sodium
c
High pressure mercury fluorescent
d
Low pressure mercury fluorescent
Q10
The symbols shows a
a
750rpm
a
Thyristor
b
1000rpm
b
Diac
c
1500rpm
c
Triac
d
3000rpm
d
Zener diode
Go to www.sparks-magazine.co.uk to freely download exercise answers 32 / SPARKS Magazine
Ans.
A light source of 6000cd is positioned 5m above a horizontal surface, Ans. the illumination on the surface immediately beneath the source is?
a
Q4
Ans.
Ans.
Ans.
EXERCISE
THE PRINCIPLES OF ELECTRICITY SUPPLY Covering Unit 304 (or EAL equivalent) ‘Understand the Principles of Planning and Selection for the Installation of Electro-Technical Equipment and Systems in Buildings, Structures and the Environment.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) Try these multiple-choice questions.
Q1
The maximum height above floor level that the switch shown in figure 1 can be located is
a
2.75m
b
2.55m
c
2.00m
d
1.75m
Q2
Which one of the following does not provide overload protection?
a
BS88 HRC fuse
b
RCD
c
BS3036 semi-enclosed fuse
d
BS1362 cartridge fuse
Q3
TN-S
b
TN-C-S
c
TT
d
TN-C The maximum value of earth fault loop impedance of a temporary electrical load supplied at a nominal voltage (Uo) of 55V and protected by a Type B circuit breaker rated at 32A is
a
0.34
b
1.96
c
1.04
d
1.44
Q5
Ans.
In which one of the following systems is neutral and protective functions combined in a single conductor throughout?
a
Q4
Ans.
Figure 2 shows a metal-clad CCU. The figure indicates two failures to comply with BS7671 requirements, these are
a
Enclosure not complete and no line conductor
b
IP rating compromised and un-protected cable entry
c
Unprotected cable entry and no barrier
d
Insufficient circuit breakers and no barrier
Ans.
Ans.
Ans.
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 33
EXERCISE
Q6
A cable is to be installed together with other circuits in a steel trunking. The wiring system passes through an area of high ambient temperature, the rating factors to be applied are
a
Ca and Cg
b
Ca and Ci
c
Cg and Cf
d
Cg, Ci and Cf
Q7
The voltage-drop in a cable is determined from the design current, length and
a
Cable c.s.a.
b
Location of circuit in respect to the CCU
c
Type of cable sheath
d
mV/A/m
Q8
A circuit supplying a distribution board from a supply intake position is called a
a
Secondary mains circuit
b
Distribution circuit
c
Sub circuit
d
Sub distribution circuit
Q9
A fuse operates on the
a
Effect of high temperature
b
Magnetic effect of an electric current
c
Electronic effect of an electric current
d
Thermal effect of an electric current
Q10
Figure 3 shows a
a
Switch-fuse
b
Isolator
c
Fuse-switch
d
Functional switch
Go to www.sparks-magazine.co.uk to freely download exercise answers 34 / SPARKS Magazine
Ans.
Ans.
Ans.
Ans.
Ans.
FEATURE
PROVE YOUR WORTH...
GET AN ECS CARD
What is the ECS card and why is it important to get one once you’ve completed your apprenticeship? Sparks finds out more… The ECS (Electrotechnical Certification Scheme) is the competence and ID card that is used by electricians to prove their qualifications, competence and identity. If you meet the card requirements, you can get an ECS card! Importantly, it also shows you meet the required level of health and safety awareness, which is now essential for gaining access to many construction sites. Most people are aware of CSCS and find it near impossible to operate without a CSCS card for certain sites and employers.
them? Being able to prove your competence is extremely important in your work environment. The ECS offers a way for you to prove your identity and your competence all on one and lists the qualifications you have worked hard for. At the start of your training you should have been registered with the JIB / SJIB by your training provider or employer. The JIB or SJIB then issue your first ECS white apprentice card to show you are formally part of the industry and it’s the first step in your ECS journey.
Going for gold Once you have your completed your NVQ or SVQ Level 3, you are entitled to apply for an installation electrician gold card. Some employers will automatically arrange this for you on completion or your apprenticeship. If not, you find out more about getting your own gold card via the ECS website – www.ecscard.org.uk If you work in different areas such as maintenance, data communications or fire and security, there are also dedicated cards for these areas too.
It’s easier now than later… The application process is straightforward and if you’re a recently qualified apprentice you won’t have to take an additional H&S test, you just have to send proof of your new qualifications, such as your certificates. But it’s important to apply when you get your apprenticeship completion, as it’s easier to do it then when all your paperwork is at hand than waiting until a later date.
Use it with pride! So whether you’ve already got your apprentice ECS card or not, make sure you get your gold ECS card once you’ve qualified – you can use it to prove your competence and give you the advantage over people who aren’t formally qualified. And don’t forget to keep the card up to date. Keeping a valid card is the best way to show customers and employers you are qualified, and it proves that you take pride in your skills. Find out more at www.ecscard.org.uk
DID YOU KNOW The ECS card is the electrical industry’s equivalent of, and is affiliated to, the CSCS. So when electricians are told they need a CSCS card, the ECS is the one that’s relevant to the electrotechnical industry. At the end of your apprenticeship you’ll have hard-earned skills and qualifications, so why not promote
SPARKS Magazine / 35
EXERCISE
PYTHAGORAS THEOREM OF RIGHT-ANGLED TRIANGLES Covering Unit 309 (or EAL equivalent) ‘Understand the Electrical Principles Associated with the Design, Building, Installation and Maintenance of Electrical Equipment and Systems.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91)
Pythagoras theorem applies to right-angles triangles only and states:
‘The square on the hypotenuse is equal to the sum of the squares on the other two sides.’
Hypotenuse (h) (a)
Expressed as a formula: h = √ a + b 2
2
ADVICE: Always start off with the formula you are going to use. Then, if necessary, transpose the formula, introduce the figures in the right locations and calculate the known value.
(b)
TRY THESE PROBLEMS. FIND THE UNKNOWN QUANTITY: Q1.
ANSWER:
h 32m
42m
Q2. 11m a
10m
ANSWER:
Go to www.sparks-magazine.co.uk to freely download exercise answers 36 / SPARKS Magazine
EXERCISE Q3.
ANSWER:
b
0.98 2.0
Q4. Find side X
ANSWER:
X 50
60
Choose one half of the triangle and allocate letters to the sides.
ANSWER:
Q5. Find kVA 50kW
40kVAr kVA
Q5. Find length H
ANSWER:
H 4.5m
5.6m
Now check your answers
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 37
EXERCISE
VOLTAGE DROP IN FINAL & DISTRIBUTION CIRCUITS Covering Unit 304 (or EAL equivalent) ‘Understand the Principles and Procedures for Selecting Wiring Systems Equipment and Enclosures.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91) The following questions concern voltage drop in consumers’ installations. REFERENCE: BS7671:2008 +A1 2011, Appendix 4, Section 6.4
Q1. Complete the following table by expressing the maximum voltage drop as a percentage (%). SUPPLY ARRANGEMENT
LIGHTING
OTHER
Low voltage installations supplied directly from a public low voltage distribution system Low voltage installation supplied from private low voltage supply. NOTE: voltage drop in each final circuit should not exceed the values given for low voltage public distribution systems
Example 1. Calculate the voltage drop for the following arrangement Final circuit 6mm2 multi-core armoured cable 30m long Heating Load current rating: 25A Supply 230V 1ph
The actual voltage drop (AVD) can be determined from the formula:
AVD = mV/A/m x Ib x Length of cable run 1000 From cable table 4D4B the mV/A/m for the cable is 7.3 then the voltage drop can be determined AVD = 7.3 x 25 x 30 = 5.48 Volts 1000 Check that the voltage drop does not exceed the allowance of 5% nominal voltage: Voltage drop allowed = % x 230 Voltage drop allowed = 5 x 230 = 11.5 Volts 100 Conclusion: The cable is suitable.
TRY THESE PROBLEMS: Q2. Calculate the voltage drop for the following arrangement Distribution circuit 16mm2 multi-core armoured cable 15m long Distribution Board current rating: 65A Supply 400V 3ph
Go to www.sparks-magazine.co.uk to freely download exercise answers 38 / SPARKS Magazine
EXERCISE AVD = mV/A/m x Ib x Length of cable run 1000 From Table 4D4B the mV/A/m for the cable is 2.4, therefore the AVD is:
Voltage drop allowed = % x 400 Voltage drop allowed = 5 x 400 = 100 Conclusion:
Q3. Calculate the voltage drop of a final circuit originating at the distribution board in question 2 above, if the circuit details are as follows:
Distribution circuit 16mm2 multi-core armoured cable 15m long Distribution Board current rating: 65A Final circuit: 3ph 400V 12kW resistive load wired in pvc single-core cables in conduit The circuit is 12m long and carries a total of 17.3A
AVD = mV/A/m x Ib x Length of cable run 1000 From Table 4D1B the mV/A/m for the cable is 15, therefore the AVD is:
Conclusion:
NOTE: The voltage drop between the origin of an installation and the load-end of a final circuit should not be greater than the percentages stated in Table 4Ab of BS7671. In the case of questions 2 and 3 above, the voltage drop for the distribution circuit should be added to the voltage drop of the final circuit to ensure the percentage allowed, (5% of nominal voltage), is not exceeded. Voltage drop from origin to load of final circuit is: 2.34V (Distribution circuit) + 3.14V (final circuit) = 5.48V (this is fine)
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 39
EXERCISE
TRANSPOSING FORMULAE Covering Unit 309 (or EAL equivalent) ‘Understand the Electrical Principles Associated with the Design, Building, Installation and Maintenance of Electrical Equipment and Systems.’ (Level 3 NVQ Diploma in Installing Electro-Technical Systems and Equipment 2357-13 / 91)
The manipulating of formulae can be one of the more difficult tasks confronting the trainee electrician. The mere mention of ‘electrical science’ and the particularly the word ‘formula’ often results in an immediate negative reaction such as ‘I am no good at maths’.
If we were given the length of one side of the room and the area, is it possible to find the length of the other side?
RULE 1:
Well, you don’t need to be! Once you have mastered the basic rules and been shown how to proceed step-by-step, the process is generally quite simple. Consider the following: a) How do we determine the area of the floor in this room?
When values are multiplied then we can divide and vice versa.
Let’s try this with the problem in (a) and see what happens if we want to find width. A=LxW
5m
A=LxW L
If we divide L x W by L, then L will divide into itself once and 1 x W = W
3m
But we cannot simply forget L so we now divide A by L. In other words, we divide the other side of the equals sign. A=W
First we need to know how to determine area.
Area = Length x width Area = 5 x 3 Area = 15m2 If we were not sure which side is length and width, does it actually matter? The answer of course is NO. Whichever way we multiply the numbers the result is still going to be 15. Next we need to consider the formula for area and simplify it to:
A=LxW
L This is as far as we need to go so let’s re-write what we have like this: W=A
with the figures inserted: W = 15
L
5
Answer: W = 3
If we had made a mistake, then the answer would not have resulted in (3) as we knew it must be. Inserting simple numbers into a formula before it is transposed can be a great help.
TRY THE FOLLOWING: b) The force acting on a conductor lying at right-angles to a magnetic field is found from the formula:
F = B IL
Where: F = force in Newtons (N) B = magnetic flux density in Tesla (T) I = current in Amperes (A) L = length of the conductor in metres (m)
Go to www.sparks-magazine.co.uk to freely download exercise answers 40 / SPARKS Magazine
EXERCISE Now, rearrange the formula to find L using the same steps as in (a) above.
c) The voltage induced into a conductor that is being cut by magnetic flux is found from:
e = BLv Where: e = induced voltage (V) B = flux density in Tesla (T) L = Length of conductor affected by flux in metres (m) v = velocity at which the conductor is cut by flux in metres per second (m/s) Rearrange the formula to make (v) the subject.
Go to www.sparks-magazine.co.uk to freely download exercise answers SPARKS Magazine / 41
EXAM ADVICE
PREPARING FOR ASSESSMENT Preparation and a clear strategy for revision is essential for a successful outcome. There are a number of assessment methods; assignments, examinations and practical tasks. Each of these methods can be sub-divided so that:
ASSIGNMENTS MAY BE...
EXAMINATIONS CAN BE...
PRACTICAL TASKS MAY BE...
Research of a given topic over
Written answers to a set of
Workshop based tasks set to time
a period of time
Evaluation of a set of criteria Studying a concept and producing a report
questions
in a work-bay / similar location designed for you to demonstrate your practical competence
Multiple-choice answers to a set of questions
Laboratory based tasks designed for
Oral response to assessor questions
you to investigate and comment on a series of events, readings or actions
Don’t worry! Most people are generally concerned about assessments and worry that they will not be able to remember key facts or be able to complete the task/s in the set time. It is important to remember that an assessment is designed to check your understanding and for you to demonstrate your competence in a particular subject area. So, although easy to say, it is not really a situation that you need worry about – look at it as a challenge, an opportunity to show what you can do and the outcome will be rewarding.
Some advice The first action to take is to establish when assessments are scheduled; dates and times need to be understood so you have a good idea how much time you have available for preparation. Also consider how many hours you are going to set-aside for revision and then try to keep to this schedule. There are several ways people revise for examinations: Looking through course notes and textbooks Seeking guidance from on-line web sites Practice using past paper questions and model answers
Studying those areas that are more difficult to understand Trying various problems set during the course and rechecking solutions Generally just hoping for best on the day of the examination
Try this idea for revising a particular subject: ELECTRIC MOTORS
Start with a plain sheet of paper and write-down the name of something that you want to revise, e.g. ‘electric motors’. Then write down anything and everything that you can remember about this subject underneath the heading you have written.
Three-phase Synchronous
Asynchronous
Single-phase Capacitor start Universal Shaded pole
If this is successful then add related topics to the ‘picture’ you have created, for example, basic electro-magnetic theory such as F = BIL or e=BLv and so on.
42 / SPARKS Magazine
EXAM ADVICE TRY THIS EXERCISE NOW FOR FAULT PROTECTION AND PROTECTIVE DEVICES
You can elaborate your ‘diagram’ as much as you like. Use words or diagrams or a combination of both. You will find that once you have started writing down headings quite a lot of additional information will appear to ‘come back’ to you. If you find you have written something and cannot remember very much about it, it is then time to look back at your notes, or seek guidance from your tutor.
Trick questions Remember the examiner is not trying to catch you out but asking ‘trick’ questions. Every question is carefully structured to check your understanding of the subject and is relevant, however obscure you may think the question is.
Practical competence Electrical Installation Engineering requires practical skills and so these need to be assessed as well as your academic knowledge. The object of the practical assessment is to gauge, or measure your ability to carry-out a series of practical performance tasks. Remember health & safety will be of paramount importance during the practical assessment and therefore you will need to be aware of what you are about to do before actually doing it. You will need PPE during workshop practical tasks and maybe a reduced PPE during laboratory practical tasks. However, remember eye and foot protection will always be needed. GOOD LUCK
SPARKS Magazine / 43
EXAM ADVICE
WRITTEN ASSIGNMENT AND EXAM GUIDANCE The purpose of the written assignment or examination is to establish your level of understanding of the subject – questions are not designed to ‘catch-you-out’ or ‘trick’ questions designed to make you fail. 1. Interpreting the question being asked. The greatest danger is to answer a question to which you know the answer, but is not actually the question being asked. ADVICE: Read the question carefully and make notes either on rough paper or on your answer book – but be sure to put a line through the notes when you have answered the question formally.
2. What a question requires you to do. The wording of a question is important as it directs you to answer in a particular way. Understanding the meaning of basic terms is therefore essential. STATE: simply means exactly that – ‘state’. A short statement not a long winded paragraph containing structured sentences – this is a waste of time. One word answers are often all that is required.
TRY THIS: State the first three tests that need to be performed on a newly completed electrical installation containing ring final circuits. (i)
(ii)
(iii)
LIST: this requires you to produce a list of actions or items. As with the ‘state’ question as described above your answer should be simple, brief and factual. NOTE: If the question requires you to ‘list in the correct sequence…’ then that is exactly what you must do. The ‘state’ question above could easily have been worded ‘List the first three tests …’ EXPLAIN BRIEFLY: as suggested this type of question requires you to provide a brief explanation about something, such as how to perform the R1+R2 test on a circuit. NOTE: DO NOT waffle the examiner will realise that you are ‘beating about the bush’ to avoid answering the question – probably because you do not know the answer! EXPLAIN WITH THE AID OF A DIAGRAM: again this is exactly what you must do. Your answer will consist of both diagram, (drawn neatly and labelled as appropriate), and a written explanation. NOTE: If you only provide a written answer or a scruffy sketch then you will not receive full marks for the answer. WITH THE AID OF A FULLY LABELLED DIAGRAM: this is slightly different to the previous requirement. The diagram needs to be drawn accurately, neatly and be ‘fully’ labelled. NOTE: When asked to draw something a pencil and a ruler should be used. Always have an eraser ready to modify the diagram should you make a mistake. (This will not be possible if you have produced your drawing using ink.). SHOW ALL CALCULATIONS: to obtain the full marks for this type of question you will need to show a formula, (in it original and transposed format if required), figures inserted correctly into the formula, an answer with the correct units attached.
44 / SPARKS Magazine
EXAM ADVICE TRY THIS: Determine, the value of fault current that is likely to flow, in the event of an earth fault occurring in a circuit that has a nominal voltage of 230V and a measured Zs of 0.25Ω. (Show all calculations)
DESCRIBE: This type of question usually is reserved for Section B questions. You will need to make a judgement of how much detail to go into. This can be done by looking at the marks allocated – the more marks the more detail needed. And, the time you have remaining – if you are short of time you will need to work fast, but this often leads to missing-out important facts.
3. Terminology. CORRECT TERMINOLOGY: absolutely essential in this examination. DO NOT use trade names such as ‘Megger’ Example: A continuity tester is not an appropriate instrument for carrying out a continuity measurement of a circuit protective conductor – why? A continuity tester may not be a low-reading ohmmeter but simply an indicator lamp or buzzer – it will confirm continuity but it does not give you a precise reading of ohms which is required to be entered onto the Schedule of Test Results. CORRECT UNITS: these must be stated when describing the required scale of a test instrument as well as when quoting formula and providing figures in statements and answers to calculations. REMEMBER: the following are the most commonly used symbols in questions relating to testing and must be clearly understood. Milli: mA or mΩ
Kilo: kA
Mega: MΩ
Amperes: A
Nominal voltage: Uo
CORRECT TITLES: so often candidates do not use the correct titles for statutory and / or non-statutory documents, and, pro-forma that is to be used to record the data collected when conducting an initial inspection or periodic inspection. NOTE: The most common errors are: > Electricity at Work Regulations 1989 – Regulations is written ‘Act’ > Health & Safety at Work Act 1974 – Act is written ‘Regulations’ Other titles that are often incorrectly stated: > Electrical Installation Certificate > Schedule of Test Results
> Schedule of Inspections > Minor Electrical Installation Works Certificate
FURTHER PRACTICE EXAMPLES: Q1. Explain briefly what effect the increase in length has on conductor resistance. (3 marks)
Q2. State three documents that specifically relate to electrical installations (3 marks)
Q3. Describe the procedure for carrying out an insulation resistance test on a newly installed lighting circuit. (10 marks)
SPARKS Magazine / 45
EXAM ADVICE
ANSWERING WRITTEN QUESTIONS The following questions are designed for you to practice answering short answer written questions. ADVICE: Remember to a) Read the question. b) Try to identify the key words and phrases that direct you to the type of answer that the examiner is expecting. c) Where a calculation is required always begin with the formula in its standard format (before showing any transformation), then insert the figures and finally show the answer. d) ‘Sign-post’ your answers. If the question is in two parts, (a) and (b), then indicate that your answers are for either (a) or (b), do not use any other sign-post such as (i) or (ii) it is confusing to the assessor / examiner.
Here are a range of short-answer questions for you to practice.
1. Rearrange the following formulae to make current the subject of the formulae. a) Power = volts x amps, (P = VI) c) Force = Flux density x current x length, (F=BIL)
b) Resistance = volts / amps, (R = V/I)
2. A conductor cuts a magnetic flux at right-angles at a rate of 6m / second. If the flux density is 4T and the length of the conductor is 2.5m, what is the value of the induced e.m.f. in the conductor?
3. State THREE non-renewable power sources that are likely to be found in the UK today.
4. By using a suitable diagram show the components and connections for a single-tube fluorescent luminaire.
46 / SPARKS Magazine
EXAM ADVICE 5. List THREE types of overcurrent protective devices that may be found in a commercial electrical installation.
6. Calculate the illumination at point (EA) immediately beneath the light source. 800cd 3.5m
EA
7. State the correct name used to describe the earth in each of the following locations a) A final circuit c) Between the MET and the main water service pipe
b) Between the MET and the incoming cable sheath d) Between hot and cold metallic water pipes in a bathroom
(a)
(b)
(c)
(d)
8. State the meaning of the following terms: Zs; Ze; R1; R2. (Zs)
(Ze)
(R1)
(R2)
9. Name THREE starting methods for electric motors.
10.Use a suitable method to determine the angle formed between the perpendicular height and hypotenuse of the triangle shown below.
8m 3m
SPARKS Magazine / 47
EXAM ADVICE
READING & UNDERSTANDING Not reading or understanding questions is the most likely reason for failing to gain full marks in a written examination. So often, students do not read the question carefully and then proceed to write down the wrong answer. The object of this exercise is to self-assess your ability to read, understand and respond to written information. Answer the following questions; YOU HAVE 5 MINUTES STARTING NOW. 1.
10. If you were alone in a deserted house at night and there was a lamp, a fire and a candle and you only had one match which would you light first?
How many animals of each species did Moses take aboard the Ark? 11. How many birthdays does the average man have?
2.
Divide 30 by ½ and add 10 (no calculators) 12. Why can’t a man living in York be buried west of the Trent?
3.
4.
Some months in the year have 31 days, some have 30 days, how many have 28?
You go to bed at eight o’clock in the evening and set the alarm clock to go off at nine in the morning, how many hours sleep would this allow?
13. If you have two coins totalling 11 pence and one of the coins is not a 10 pence piece, what are the two coins?
14. How much dirt is there in a 2’x2’x4’ hole? 5.
If a doctor gave you three tablets and told you to take one every half hour, how long would they last?
6.
How many sides does a circle have?
7.
How far can a dog run into the woods?
8.
Which country has a fourth of July, Britain or America?
9.
A man built a house of rectangular construction, each side having a southern exposure. A bear came wandering by, what colour was the bear?
SCORE:
48 / SPARKS Magazine
15. If two monkeys sit in a corner of a room and look at another pair in another corner and so forth until every pair in a corner looks at another pair, how many monkeys could say that they were looking at other monkeys?
16. Would it be all right for a man to marry his widow’s sister?
17. If you drove a bus leaving Croydon with 40 passengers, dropped off seven and picked up two at Addiscombe, stopped at Sanderstead and picked up ten, went to Purley, dropped off eight there and picked up five, then drove on to arrive in London two hours later, what would the driver’s name be?
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