Smoke alarms

[Qedelec]

Does any one know what the current regs are on mains operated smoke alarms?

I was under the impression that you can fit one alarm from the lighting circuit but if there are more than one, that they must be interconnected (so that one triggers them all) and must be supplied from their own ring circuit.

Don't you just hate to hear customers telling you your job.

 

[Spark123]

Summary of what the OSG p56 says,
If house is not more than two storeys:
1) at least one on each floor
2) within 7m of kitchens and living rooms or other areas where fires may start (internal garages etc)
3) Within 3m of bedroom doors,

Install alarms in accordance with manufacturers instructions, generally at least 300mm from a luminaire.

Alarms to be interconnected
Perminently wired to a separate way in the cu or supplied from a local, regularly used lighting ckt.
Must have battery backup.
Except TT supplies, smoke alarms should not be RCD protected.

Doesn't mension wiring as a ring.

 

[Qedelec]

Thanks for the reply spark.

I have a feeling that I read some where about them being on a ring. Could have been in Professional Electrician.
As I recall there are several classes of alarm circuits and one required a ring so that if power was lost due to the fire the other arm would give a supply.
I thought at the time it was overkill as by the time the heat has melted the cable the house would be ashes.

I will have to root through my back numbers.
Thanks again.

 

[Adam_151]

I thought at the time it was overkill as by the time the heat has melted the cable the house would be ashes.

Not as overkill as wireing them in pyro would be

 

[plugwash]

afaict you can put them on a local lighting cuircuit but this is only really feasible if you only have one lighting cuircuit. otherwise you have potential issues from interconnecting between cuircuits (i dunno how the interconnect systems work so i dunno just how bad this is but it still doesn't seem the best of ideas).

once your interconncting you need to wire between them all anyway by which point you may as well take a feed from the CU to the first one and then continue to the others using 3&E.

 

[Qedelec]

Except, plug, there are now wireless smoke alarms so in theory that interconnecting would be acceptable.