Domestic extention and smoke alarms

[Dunk17]

Afternoon all,

Ive looked at the building regs but can't seem to find anything, i remember reading something that said when fitting smoke alarms off a lighting circuit you need to put some form of isolation in, is that correct?

I'm also looking to install nest alarms, do they all need to be wired?

Thanks for your help.

 

[littlespark]

No isolation needed between lighting and smoke alarms, but would be better all smokes on a separate circuit themselves.

I believe Nest alarms come in mains or battery versions. (could be wrong, never fitted one)

 

[Risteard]

No isolation needed between lighting and smoke alarms, but would be better all smokes on a separate circuit themselves.

I believe Nest alarms come in mains or battery versions. (could be wrong, never fitted one)

I would consider it better practice to feed them off a lighting circuit. Obviously this is only appropriate for domestic systems (and not ones with a fire alarm panel).

 

[littlespark]

I would consider it better practice to feed them off a lighting circuit. Obviously this is only appropriate for domestic systems (and not ones with a fire alarm panel).

If its a new install, smokes on separate.... Tag off the lighting if its an addition, and you cant get back to the board.
What if you were working on the lighting circuit? Turn off the smokes? I know theres battery back up, but i'd prefer full fire detection if I can get it.

 

[pc1966]

This implies an isolator is a requirement for non-domestic arrangements:

Fire Isolator Switch – a legal requirement

According to leading fire and security products supplier, ESP, there are still a lot of installers who are unaware that a fire isolator switch is a legal requirement with all new fire alarm systems being installed in the UK - coming under the BS539 Part 1 Standard.

www.voltimum.co.uk

Not sure what you would use in a domestic arrangement, the obvious thing would be one of the "emergency light test" style of key switches but typically they are grid ones (could put it along side another grid module to replace an existing light switch of course)

I agree with @Risteard that putting it on the light circuit is safer - if faulty they are more likely to have it fixed!
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What if you were working on the lighting circuit? Turn off the smokes? I know theres battery back up, but i'd prefer full fire detection if I can get it.

True, but I guess the time spent with anyone working on lights is small.

 

[littlespark]

There's no requirement for isolation in domestic.

Like i said, a new install, i would put smokes on their own circuit. Just for easy identification, separation of circuits etc.
Tapping off the lights isn't wrong, or right, or safer, or less safe... its just done a different way. Like socket radial vs ring.

I have actually tapped an attic light off the base of a smoke detector to get a feed, which was fed itself from the lights.... all the feeds were at switches i couldnt get down to.

 

[Dunk17]

Thanks for the replies.

Having a dedicated circuit for the extention is easy enough, it's more difficult in the house. For example, putting them on the first floor would be difficult with the loft being boarded and full, would installing battery ones linked to the wired extention ones pass building regs?

 

[littlespark]

Thanks for the replies.

Having a dedicated circuit for the extention is easy enough, it's more difficult in the house. For example, putting them on the first floor would be difficult with the loft being boarded and full, would installing battery ones linked to the wired extention ones pass building regs?

That depends on the LABC. Some will, some wont. And depends on the make of detector. Aico mains can be retrofitted with a radiolink base, so can "talk" to the newer battery powered detectors

 

[Midwest]

I think building regs stipulate mains wired battery back up for building alterations/extensions.

Edit, beaten to it.

 

[Dunk17]

That depends on the LABC. Some will, some wont. And depends on the make of detector. Aico mains can be retrofitted with a radiolink base, so can "talk" to the newer battery powered detectors

I was looking into installing Nest
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I think building regs stipulate mains wired battery back up for building alterations/extensions.

S

I think building regs stipulate mains wired battery back up for building alterations/extensions.

So it's only applicable to the extention not the whole house? If so, installing wired in the extention and battery in the house linked would potentially satisfy LBC?

 

[davesparks]

No isolation needed between lighting and smoke alarms, but would be better all smokes on a separate circuit themselves.

Smokes should be wired to a regularly used lighting circuit, I believe this is the recommended method in the BS.
This is to ensure that any failure of the circuit is readily identified and rectified.

A dedicated circuit is unlikely to be noticed if it trips, or fixed with any hurry.

 

[Dunk17]

Smokes should be wired to a regularly used lighting circuit, I believe this is the recommended method in the BS.
This is to ensure that any failure of the circuit is readily identified and rectified.

A dedicated circuit is unlikely to be noticed if it trips, or fixed with any hurry.

I think the isolation is very much dependant on the local building control, attached is a document from temside stating it needs to be in place

 

[westward10]

Smokes should be wired to a regularly used lighting circuit, I believe this is the recommended method in the BS.
This is to ensure that any failure of the circuit is readily identified and rectified.

A dedicated circuit is unlikely to be noticed if it trips, or fixed with any hurry.

Approved Doc B and BS5839:6 cite an independent circuit or the use of a lighting circuit.

 

[pc1966]

I think the isolation is very much dependant on the local building control, attached is a document from temside stating it needs to be in place

If it is coming from the lights, so you can't isolate it without no lights, then I would personally want to see some means of isolation.

You don't want it to be accidentally switched which is why I would go for a keyswitch sort, but I guess a FCU that is out of normal reach is another option (might be an issue for disabled access of course...). Hopefully others on here will know better!

 

[westward10]

I think the isolation is very much dependant on the local building control, attached is a document from temside stating it needs to be in place

I could be incorrect here but I believe the purpose of isolation was so as not to interfere with the lighting for maintenance and was quoted in Approved Doc B. This is no longer quoted in Approved Doc B so I would actually question that as they may be using out of date requirements.