Smoke Alarm

[Low Voltage]

Hi Guys,

Not been on for a while due to illness but now back and itching to continue with this great forum.

Just had my tech assessment and was stunned when we went to my site visit the guy from Elecsa said.

"Why have you put the smoke alarm on the non RCD side of the board (Used a 4+4+2 Wylex)

Told him why so the Alarm is segregated from the remaining circuits.

Any thoughts on this been in this game a long time, have I missed a trick with this new 17th Edition.

Cheers

 

[cheggers]

Fitting

We recommend the use of 6243Y 3 core and earth PVC insulated

cable to BS6004 standard. Building Regulations and BS 5839: Pt 6 state

that mains only alarms with back-up, can be wired from a dedicated

circuit at the distribution board, or they can be wired from a regularly

used lighting circuit. In both cases, all hard wired alarms should be on

a single final circuit.

this was from aico web site http://www.aico.co.uk/downloads/smoke_q&a.pdf

 

[batty]

Hi Guys,Not been on for a while due to illness but now back and itching to continue with this great forum.

Just had my tech assessment and was stunned when we went to my site visit the guy from Elecsa said.

"Why have you put the smoke alarm on the non RCD side of the board (Used a 4+4+2 Wylex)

Told him why so the Alarm is segregated from the remaining circuits.

Any thoughts on this been in this game a long time, have I missed a trick with this new 17th Edition.

Cheers

Are cables installed in walls or is earthing TT system if not then no RCD protection is needed.

Batty

 

[NozSpark]

Here are a couple of regs that apply..

RED BOOK

All cables burried in walls at a depth of < 50mm shall either have RCD protection or be installed in earthed metalic protection (eg. conduit or SWA)

FIRE ALARM REGS

Fire detection systems shall either be suppled by a dedicated circuit or a commonly used lighting circuit (battery back up required)

Fire alarm systems shall not be protected by a RCD which also supplies a socket circuit

Sorry no reg no's and definately not word for word

 

[a2]

Hi Guys,Not been on for a while due to illness but now back and itching to continue with this great forum.

Just had my tech assessment and was stunned when we went to my site visit the guy from Elecsa said.

"Why have you put the smoke alarm on the non RCD side of the board (Used a 4+4+2 Wylex)

Told him why so the Alarm is segregated from the remaining circuits.

Any thoughts on this been in this game a long time, have I missed a trick with this new 17th Edition.

Cheers

Glad your better and it's great to have you back on board.

:x

 

[Evans Electric]

I don't think the new regs have covered fire alarms, personally I think they are still best fed from a local lighting circuit,. A dedicated circuit could be switched off and the occupiers may never know.

Unfortunately the lighting circuit will now have an RCD on it ,to comply, but that has been dumped on us from above so theres nothing you can do .

Deke

 

[batty]

I don't think the new regs have covered fire alarms, personally I think they are still best fed from a local lighting circuit,. A dedicated circuit could be switched off and the occupiers may never know. Unfortunately the lighting circuit will now have an RCD on it ,to comply, but that has been dumped on us from above so theres nothing you can do .

Deke

All the smoke alarms I fit have a green light to tell you it has power and beep if power is disconnected. Why do smoke detectors have to be RCD protected.

Batty

 

[a1]

I read somewhere that they don't need to be RCD protected (under 17th edition too), but I can't back it up.

Does it really make a difference though? They have battery back up and audio warning (as Batty mentions, some have the green 'power' light too).

 

[Theorysparky]

Batty

have a gander at this article

http://www.gadsolutions.biz/electrical/regulations/designing-for-the-17th.html

consider the issue of cables in walls as per reg then it makes sense

where this guy suggests the cct goes is the key

 

[Evans Electric]

Presumably if the fire alarm cable runs flush up a wall and is not 50mm deep and is not protected by earthed metalic conduit or is not wired in Pyro or FP200 then it must be protected by an RCD. Personally I think its gone too far !! I guess if the wiring is only within the ceiling, no RCD is needed.

I take Admin's point but people would take no notice and assume they were working,until too late, methinks !!

 

[batty]

Battyhave a gander at this article

http://www.gadsolutions.biz/electrical/regulations/designing-for-the-17th.html

consider the issue of cables in walls as per reg then it makes sense

where this guy suggests the cct goes is the key

Bungalows would need no Rcd protection as long as cables are not installed in wall up to roof and on a rewire most houses have cupboards that cables can be run in trunking up to second floor but some jobs this would not be possible. Every job is different but I would not put smokes through an RCD unless it was a TT system or there was no way cables could not be installed in walls.

Batty

 

[Evans Electric]

I read the URL above and am non the wiser . Still think it best to connect them to the lighting .

 

[batty]

I read the URL above and am non the wiser . Still think it best to connect them to the lighting .

I think it is better to put them on there own circuit. There is no reason that they should trip out if they have been wired correctly. The circuit is never going to be overloaded by a few smoke detectors is it and when doing pir's the inspector will thank you.

Batty

 

[SPECIAL LOCATION]

I read the URL above and am non the wiser . Still think it best to connect them to the lighting .

So when a bulb blows & trips the MCB..

or customers doing alterations to his lighting circuit with the power off

got not mains supply for smokes? :_|

There is also possible risk of DIY light alterations dissing power to smokes?

 

[steptoe]

I read the URL above and am non the wiser . Still think it best to connect them to the lighting .

agree,

a customer will always report a fault or try sort it out if the lights stop working.

would they even notice if the smokes stopped working????!!!?!?!?!?

 

[batty]

agree,a customer will always report a fault or try sort it out if the lights stop working.

would they even notice if the smokes stopped working????!!!?!?!?!?

How could they not notice when they beep every few minutes.

Batty

 

[Apache]

How could they not notice when they beep every few minutes.Batty

Wouldn't they just remove the back-up battery?

 

[Evans Electric]

You make a good point Specs. But I can't help thinking if the dedicated MCB were switched off, the householder would probably never know. The light circuit being off would be a nusance and more likely to be restored.

It is however , a very, grey area. Perhaps they should be fed via a locked , 1way unit next to the CU or built into the CU ?

 

[Evans Electric]

Wouldn't they just remove the back-up battery?

Yes they would, how many battery only ones do you see hanging open without a batt ?

 

[steptoe]

agree,a customer will always report a fault or try sort it out if the lights stop working.

would they even notice if the smokes stopped working????!!!?!?!?!?

maybe i was pushy shovedy