Smoke Alarms in domestic/holiday homes - new build, bank holiday wiring

No. They can be supplied from a local, regularly used lighting circuit.

Yes.

Source: On-Site Guide para 7.4.1

Thanks Andy,

It is the right way to do it, but I am stuck in rural Devon on a BH, nearest DIY store is 1 hr drive!!!!

Might have to bodge it!

IEE on site guide states that they can be supplied from a seperate MCB/fuse which is not RCD protected, OR a regularly used lighting circuit, which is also not RCD protected. The TLC (on-line electrical suppliers) smoke alarm guide however states that only battery back-up alarms can be connected to a light circuit, and non-battery back-up larms have to have their own circuit.

IEE guide says they are 'required' to be interlinked

The IEE giude states that they are required to have a battery backup.

Incidentally, the screwfix mains optical smoke alarm (non-battery back-up) are a different make to the mains ionisation alarms (battery back-up) and the instructions state they are not compatible with other brands! Neil

AC only smoke/heat alarms in 2000 Approved Document B, which covers England & Wales, conbfirms that this type must be connected direct to unswitched/dedicated spur on consumer unit. Those with battery back up, can come off adjacent unbswitched lighting circuit. This brought Bldg Regs into line with IEE Regs; Document B is free; download off links page at web site below.

AC only will be cheaper to buy, but not when installed, & are as much use as a chocolate teapot in a power cut; or what the Yanks delightfully call a brown out!!

Manuals [pdf's] with wiring diagrams at

Would be wary of some Screwfix list as dont appear to be BS Kitemarked; anyone can say Made To BS..but it needs independent Testing to confirm compliance.

Most smoke alarm manufacturers state that their products cannot be interlinked to another manufacturers alarm.

Also, I prefer to run the smokes (with a battery backup) off the lighting as it is soon obvious that there is no mains power.

Adam