A couple of Smoke Alarm questions?

13 Jul 2005
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United Kingdom
1. Power Source

I intend connecting my smoke detectors to an existing lighting circuit. I believe this is one of the valid options, the other being to connect to a dedicated circuit. I think connecting to an exisiting light circuit is a better option that a dedicated circuit as if for some reason the circuit fails I will hopefully know sooner as I will notice the lights not working. However, I am sure I read somewhere that if an existing lighting circuit is used to power the smoke alarms you must provide a method to isolate the power to the smoke alarms without isolating the lights, is that true? If it is what's the preferred method to achieve this?

2. Interlinking cables

I will have at least two smoke detectors, these will be interconnected as it seems is the requirement. questions:

(a) What's the preferred cable to use for this, I have some standard triple & earth but I was wondering if there was a smaller (thinner) option?

(b) I believe it is a requirement to be able to distinguish the smoke detector interconnecting cables from other 'normal' cables such as those supplying mains power. What's the preffered approach for this? I

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Assuming this is a domestic installation, then:

1 - lighting circuit is fine, don't put in any isolator or switch, otherwise they will be switched off and left like that.
2a - 1mm, 3 core and earth is the usual choice. There is nothing smaller, and it has to be rated for mains use anyway, so the likes of phone cable etc. can't be used.
2b - not required.
Thanks for the input,

Yes, it's domestic.

All pretty straight-forward then. I must say there seems to be quite a bit of confusing/conflicting information kicking around regarding smoke detector installation!

Thanks again,

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I will have at least two smoke detectors, these will be interconnected as it seems is the requirement. Steve

Is it a requirement to interconnect smoke alarms? I can see it is a good idea....

My house is 1997 built and has smoke alarms on upstairs landing and hall. It now has a heat alarm in the kitchen installed last year.
Routine pressing of the test button earlier this year showed one had failed. Its replacement which was virtually identical stated it had a 10 year life. No-one mentioned that before and they have both now been replaced (the smoke alarms that is). But they definitely weren't interconnected, is this new regs?

I wonder if I shall remember to replace again in 10 years?!

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