This Question of the Day, concerning the requirements for a bungalow re-wire and its smoke alarm circuit, has been answered by the ECA (Theme – Regulations & Legislation):
Question: Can you clarify the requirements for connecting the smoke alarm circuit on a re-wire in a bungalow. I have installed a split 17th Edition consumer unit with the smoke alarm on its own independent MBC circuit - this is RCD protected, along with three other separate circuits on the RCD protection, which is on one half of the board.
The way I see it is that I have complied with Part P, the On Site Guide, the Electricians Guide to the Building Regulations, BS 5839 Part 6 and, of course, BS 7671:2008.
However, the local Building Control Office is insisting that this is incorrect, and that the MCB for the smoke alarm should be lifted out of the RCD and placed outside of the RCD protection and any other circuits. The smoke alarm has battery back-up. The request to move this circuit out of RCD protection and away from any other circuit does apply in BS 5839 if it were mains wired only.
Can you confirm if what the Building Control Office is requesting is correct? Also, am I correct in my interpretation of all the above regulations and guidelines?
I have attached a copy of the of the consumer unit layout for your reference. Please help, as the Building Control Office has already been incorrect on two other situations, with snagging me for non-compliance of BS 7671:2008.
Please click on the link below to download the consumer unit layout attachment (small jpg).
Answer: What you have done is compliant, but we prefer smoke detectors to be connected to the lighting circuit so that if the MCB trips it is likely to get noticed sooner.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link:
www.voltimum.co.uk/consult.php?universe=consult.index.questions