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From the helpline We continue with our series of answers to some of the more frequently asked questions put to our Technical Helpline.

QUESTION ANSWER

Is it necessary for a fi re alarm detector to be installed in the lounge of new domestic premises to provide life protection where a Grade D Category LD2 system is installed?

QUESTION QUESTION Regarding the above answer, under what circumstances might a carbon monoxide fi re detector be installed? Yes. Guidance documents issued by governments for the building regulations in the United Kingdom jurisdictions, namely Approved Document B – Fire safety (England and Wales), the Technical Handbook – Fire (Scotland) and Technical Booklet E – Fire safety (Northern Ireland) recommend the installation of a fire detection and fire alarm system in accordance with BS 5839-6 (the standard for fire alarm and fire detection systems) for new domestic premises.

Consequently, BS 5839-6 recommends that the lounge of new domestic premises (defined as a ‘principal habitable room’) should incorporate a smoke detector. Alternatively, for such rooms a carbon monoxide fire detector (CMFD) may be installed ((Note D) to Table 1 of BS 5839-6 refers).

QUESTION ANSWER

A carbon monoxide fire detector (CMFD) may be suitable in a dwelling where a fire safety risk assessment reveals that a smoke detector may increase the risk of false alarms, for example, where the lounge is open to the kitchen. False alarms in fire systems can have a detrimental eff ect on fire safety and therefore an emphasis is placed on keeping false alarms to a minimum (clause 12 of BS 5839-6 refers).

It should be noted that CMFDs respond faster to slow burning fires than typical smoke detectors but respond slower to flaming fires than smoke detectors. Therefore, the risk assessment should also consider the number of floors, rooms and circulation areas in the premises and the ability of the occupants to move to a place of safety in the event of fire, so that this slower response time does not impair evacuation of the premises.

ANSWER

I plan to install a fi nal circuit and control wiring for a central heating system (CHS). Is it necessary to issue an Electrical Installation Certifi cate (EIC) for the circuit and associated control wiring? Yes. The fundamental principles of BS 7671 state the requirements intended to provide for safety of electrical installations and within these requirements Regulation 134.2.1 calls for appropriate inspection, testing and certification of any erected installation.

Therefore, where a new circuit is installed for a CHS and associated controls, as for any other circuit, an EIC needs compiling and issuing to the person ordering the work.

Similarly, where existing final circuit or control wiring associated with a CHS is being altered or added to, either an EIC or a Minor Electrical Installation Works Certificate (where appropriate) will require compiling and issuing.

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QUESTION

I want to replace a consumer unit and although the existing unit is currently wall-mounted and meets Regulation 132.12 regarding accessibility, the mounting position has inadequate width to accommodate a new unit. Can I mount the new unit vertically?

QUESTION

Regarding the answer directly above, where manufacturer’s documentation confi rms the consumer unit is suitable for vertical mounting the switchgear and controlgear will be operated left and right (rather than up and down). Does this comply with BS 7671?

QUESTION

I plan to replace a length of damaged insulated and sheathed fl at cable (twin and earth) installed some 20 years ago in a wall at a depth of not more than 50 mm from the surface. However, to meet the requirements of BS 7671: 2008 (including Amendment 3); this installation method means the cable should have additional protection by RCD in accordance with Regulation 522.6.202. Do I have to provide such protection to carry out this repair?

QUESTION

In relation to the question directly above, the cable supplies a socket-outlet. If I also replace the socket-outlet with a similar socket-outlet, do I have to install additional protection by RCD in accordance Regulation 411.3.3? ANSWER

Yes, provided the manufacturer’s documentation confirms that the particular consumer unit and enclosed switchgear and controlgear are suitable for vertical mounting and meets relevant standards, such as BS EN 60439-3.

ANSWER

BS 7671 does not require the operation of switchgear and controlgear to be identified by orientation. Identification for the installation (including switchgear and controlgear) is required to be provided by marking, labels and notices which are legible, durable and fixed in appropriate positions, to provide for safe operation, whilst minimising confusion to the observer (Section 514 (Identification and notices) refers).

ANSWER

No. Provided you install the new length of cable using exactly the same route as the existing cable, this repair work will not be classed as an addition or an alteration. However, where possible it is always good practice to meet the current standard of BS 7671, especially where it may improve safety for the user of the installation.

Also, if the installation since construction has not been subject to any additions or alterations, a warning notice to indicate wiring to two versions of BS 7671 should be aff ixed at or near the appropriate distribution board (consumer unit).

STION

ANSWER

No. Although it is good practice to meet the current requirements of BS 7671, replacement of an accessory with a similar accessory is classed as maintenance work and not an addition or an alteration.