connecting smoke alarm to lighting circuit

uncle betty

Hi folks,

Need a little help here if possible, please.

I'm running from the consumer unit, two-way switches to a pendant, and will incorporate a smoke alarm as well on the same breaker.

I know I have to take a feed from the breaker, but can I just loop neutral and earth from the smoke alarm to the pendant ceiling-rose ? Don't have to bring those two all the way back to the board do I ?

Thanks in advance,

betty

fishdog

No problem, just take the earth and neutral from the ceiling rose. Ensure that the live for the somke is:

a) Not switched
b) On the same circuit

uncle betty

Great stuff. Thanks for the quick reply. Much appreciated.

bertie1

I assume you know that a smoke alarm is classed as a safety circuit & should be on an mcb seperate to the lights so that if a bulb blows the mcb your smoke alarm will still work in the event of a fire. It is in the regs.

Andrea B.

No problem, just take the earth and neutral from the ceiling rose. Ensure that the live for the somke is:

a) Not switched
b) On the same circuit

Smoke alarms don't need earths, however it is not practice to share a circuit, ie, using a neutral from one to supplement another. As per Bertie1's advice, it should be on it's own circuit.

fishdog

I assume you know that a smoke alarm is classed as a safety circuit & should be on an mcb seperate to the lights so that if a bulb blows the mcb your smoke alarm will still work in the event of a fire.

Mains type smoke alarms have a back up battery as standard. If the battery is not working properly the alarm will beep.

It is in the regs.

I dont thimk so! Unless it has changed very recently. Perhaps you can show me where ??

Smoke alarms don't need earths

Correct. It is standard practice to supply earths to all point in all circuits. For example plastic light switches with plastic switch boxes do not require earths either yet they should have an earth.

however it is not practice to share a circuit, ie, using a neutral from one to supplement another

Exactly that is why I said:

Ensure that the live for the somke is:
b) On the same circuit

uncle betty

Very interesting, thanks to all for your input. However...

It is still taught in Phase 2 FAS that smoke alarms should be all ''supplied directly from the same lighting MCB, for safety reasons, as all units are interconnected... a lighting circuit automatically provides monitoring of the supply.''

Which is possibly why the recommended system for domestic is Grade D (one or more mains with battery back-up). So it wouldn't really matter if the MCB tripped.

And I've got the Reg.'s in front of me and I can't find the reference you mention bertie1 - can you put me right onto it ?

Thanks again to all of you.

Andrea B.

Correct. It is standard practice to supply earths to all point in all circuits. For example plastic light switches with plastic switch boxes do not require earths either yet they should have an earth.

Quote:
however it is not practice to share a circuit, ie, using a neutral from one to supplement another
Exactly that is why I said:
Quote:
Ensure that the live for the somke is:
b) On the same circuit

Apologies fishdog, hadn't fully absorbed your original post

fishdog

No bother Andrea B

bertie1

uncle betty wrote: »

Very interesting, thanks to all for your input. However...

It is still taught in Phase 2 FAS that smoke alarms should be all ''supplied directly from the same lighting MCB, for safety reasons, as all units are interconnected... a lighting circuit automatically provides monitoring of the supply.''

Which is possibly why the recommended system for domestic is Grade D (one or more mains with battery back-up). So it wouldn't really matter if the MCB tripped.

And I've got the Reg.'s in front of me and I can't find the reference you mention bertie1 - can you put me right onto it ?

Thanks again to all of you.

Chapter 56 supplies for safety services, there is a lot more to learn than what is thaught in phase 2 , if a Reci inspector came out he would be looking for a seperate mcb designated to the smoke alarm system. There is an led on the smoke detectors ( mains operated) for monitoring the mains.

uncle betty

bertie1 wrote: »

Chapter 56 supplies for safety services, there is a lot more to learn than what is thaught in phase 2 , if a Reci inspector came out he would be looking for a seperate mcb designated to the smoke alarm system. There is an led on the smoke detectors ( mains operated) for monitoring the mains.

ETCI National Rules, 3rd. Ed.

Chapter 56 : Safety Services

560.2 ''This chapter does not apply to domestic and similar installations.''

560.3 ''Mains-operated smoke alarms are not in the scope of this chapter.''


Instead of talking to me like I'm four years old, about how much I have to learn, you might have read the first page of the Chapter you set me for homework.

I doubt we will have any more to do on smoke alarms, and if we did, it would be to build on what we've done in Phase 2, not to go and do it completely differently. What sense would that make ?

Edit - the answer is in Annex 43A

3. Radial Final Circuits

''A radial final circuit for lighting circuits may also supply small items of equipment, none of which exceeds 300W rating, e.g. bell transformers, shaver outlets, alarm systems.''

Can't believe I didn't see it first time.

So what can a RECI man do about that ?

fishdog

if a Reci inspector came out he would be looking for a seperate mcb designated to the smoke alarm system

Why would this be any better??

On all of the occasions that I have seen a RECI inspector (x 12, once my work) or an ECSSA inspector (x 12ish, all my work) inspect a domestic installation he seemed content that the smoke detectors were on a lighting circuit and rightly so.

(BTW, I would imagine that most of the inspectors are now with the ECSSA and not RECI because ECSSA has a far larger membership!)

Having smoke detectors on their own dedicated circuit would not make them any safer.

there is a lot more to learn than what is thaught in phase 2

This is true, but alot of the basics that many of us forget are taught early on.

bertie1

I suppose you read 314.1 & 314.2 as well

Stoner

fishdog wrote: »

Why would this be any better??

On all of the occasions that I have seen a RECI inspector (x 12, once my work) or an ECSSA inspector (x 12ish, all my work) inspect a domestic installation he seemed content that the smoke detectors were on a lighting circuit and rightly so.

(BTW, I would imagine that most of the inspectors are now with the ECSSA and not RECI because ECSSA has a far larger membership!)

Having smoke detectors on their own dedicated circuit would not make them any safer.


This is true, but alot of the basics that many of us forget are taught early on.

Have to agree with fishdog here in principle as he answered the OPs DIY based question. I know that having a smoke on its own MCB is in the regs and the regs.

We've carried out installations to many apartments and houses both private and to council specs, we typically connect the Smoke detector to an MCB that feeds the doorbell
I guess the best advice is to follow the regs, but in this case that would involve working on a consumer unit, and I would not advise that the OP does that, working on a consumer unit is not a DIY job and should be left to an electrician. although it is a battery backed up unit and the advice fishdog gave would "work" and is far better than a cheapo battery only operated detector.

On another note fishdog, I've noted that more than once you have pointed out that the "ECSSA has a far larger membership" than RECI, where did you get those figures, do they take into account the size of the members ?, for example if Mercury engineering employ 1200 electrical people and are RECI members, does that count as one membership and is that equal to Joe Bloggs electrical who operates on his own? just interested in the info if you have it.

fishdog

On another note fishdog, I've noted that more than once you have pointed out that the "ECSSA has a far larger membership" than RECI, where did you get those figures

From an official news letter from the ECSSA.

I know that having a smoke on its own MCB is in the regs

I dont think that it is! I have never seen this.

Hoagy

fishdog wrote: »

I dont think that it is! I have never seen this.

I think you're right there, it's not in the ETCI.

It's covered in BS 5839.

Grade D smoke alarms (mains and battery) can either be
on a dedicated circuit or a frequently used lighting circuit

Grade E smoke alarms (mains only) must be on a dedicated circuit.

And all interconnected alarms must be on the same circuit.

fishdog

I think you're right there, it's not in the ETCI.

Me too !

Grade D smoke alarms (mains and battery) can either be
on a dedicated circuit or a frequently used lighting circuit

This is the type used in domestic situations.

Stoner

yeah fair enough, I thought it was mentioned in the regs so i hold my hand up, I though it was one of those ignored regs. I agreed with the answer, like i said we never put them on their own circuit and have never had an issue with either RECI or the county council specs they always go on a circuit with either the door bell or the intruder alarm.

fishdog,
so the ECSSA published these figures, did they comment on how big each member contractor is or the volume of installations they certify v RECI?

I would like to view some independent information as I am interested, or even something from the ESB relating to how many ECSSA certs vs RECI certs are processed.
I guess it comes down to how figures are reported, is it simply down to the amount of members regardless of their size, or is it down to the amount of installations that would be regulated by either body.

fishdog

so the ECSSA published these figures,

Yes. I read it in a news letter that they sent out when I was a member. Many of the newsletters are on their website, look through and you may find it or simply email them.

did they comment on how big each member contractor is or the volume of installations they certify v RECI?

I cant remember!! I think each company is considered a member, but I am open to correction.

Ring them! They are very pleasent to deal with, 06437266

I found them very helpful if I was unsure of regulations etc.

uncle betty

bertie1 wrote: »

I suppose you read 314.1 & 314.2 as well

No, did you read Annex 43A ?

But I'll make a couple of observations - firstly, do most DIYer's you all know of have a copy of the Rules, or know what is taught in phase 2 ?

uncle betty

Ridiculous moderation.

Stoner

uncle betty wrote: »

But I'll make a couple of observations - firstly, do most DIYer's you all know of have a copy of the Rules, or know what is taught in phase 2 ?

very good point, this is a DIY section, not a battle of the regs


This was a discussion more than anything else IMO.

DIYers should be able to ask questions here and not get hammered with the regs, the main thing is safety.

some of the advice you got was incorrect regarding the regulations, but it was not dangerous or bad practice, either approach would yield a working unit, one would just have required some unnecessary work, and it was cleared up on the forum


i.e you have your answer, do as fishdog advised and you will be fine.

hopefully this will end this.

uncle betty

This was a discussion more than anything else IMO.

I'd still maintain that discussion is best facilitated by listening/reading to other people's contributions properly.

But point taken, and sincere thanks to all who took the time to reply.

For the record, I'm a second year apprentice spark. Just want to be as good as I possibly can at the trade.