Smoke detector circuits

[mattx029]

I am after some advice regarding smoke/heat detector circuits as I want to install a circuit whilst my house is being rewired.

I was panning to power 8 detectors on there own mains circuit from a 6A 30mA RCBO in the consumer unit. I would then run 1.5mm twin and earth from the consumer unit to the first detector and three core and earth (to interlink) to subsequent detectors terminating the circuit at the final detector.

Is this correct?
Do I need to use fireproof cable?

 

[echoes]

Yes that's correct.
Fire-proof cable is not required.
1mm² cable would suffice, unless for some obtuse reason, the instructions say otherwise.

If all the cables are in ceiling voids and none are buried in walls, there is no need for an RCBO (unless there is some other reason, like a TT supply); and MCB would be OK.

 

[EFLImpudence]

Also, I think, a good idea to have one light on the circuit so that it would be noticed if, for whatever reason, the mcb/rcbo has tripped.

 

[ban-all-sheds]

A proper power failure alarm would be better, no?

 

[mattx029]

What is a "proper power failure alarm"?
I was planning to use detectors with 9v battery backup.

 

[echoes]

The little green lights on the alarms will tell you when they have mains power.
Having a regularly used light on the circuit is good practice, but ironically, it is far more likely that a lamp would trip a circuit breaker than a smoke alarm. (depends what type of lamp)

 

[ban-all-sheds]

http://www.google.co.uk/search?q=power+failure+alarm

 

[ban-all-sheds]

The little green lights on the alarms will tell you when they have mains power.

True.

Having a regularly used light on the circuit is good practice, but ironically, it is far more likely that a lamp would trip a circuit breaker than a smoke alarm. (depends what type of lamp)

You do tend to notice when that happens though, and turn it back on.