Domestic Rewire (Smoke Alarms, Heat Detectors And More)

[jas0n]

Hello everyone. does anybody know if a new rewire in a home requires the smoke alarms and heat detectors to be on there own mcb. Also as the house has a ground, 1st and 2nd floor (not including kitchen) would each floor require the own circuit for lighting and power or could the 1st and 2nd floor have a circuit for lighting and a circuit for power?

 

[Zeespark]

Aico do a handy pocket sized guide for this sort of situation, you can have one mailed to you via their website.

Andy Guinness

 

[jas0n]

Thanks Andy, much appreciated,  just registered for the electrical contractors handybook

 

[loonytoon]

Or download the handy app for your smartphone. Its free on android, not sure on ithingy, but guess it is on there too.

Hth. Rob.

 

[steptoe]

if its like anything else ithingie its gonna cost  :slap

 

[Evans Electric]

Last time I looked, it was "recommended " that smoke detectors are included in major domectic electrical work ,  we always include them .

How you connect them has  been left , as usual, in "Hairy Fairy " land  by the powers that be so I'll make it easy .   In my opinion feeding smoke detectors from their own MCB is not a good idea , it borders on the stupid and the inane .   The reasons are obvious and we've discussed them numorous times.

So connect them to a frequently used lighting circuit .

As regards your circuits in the 3 story house you need to design the installation based on the information before you ,   we don't know how big this house is , is it  Downton Abbey or a 3 bed town house ?      Theres  nothing that says you must have a circuit per floor . 

If its an ordinary house your minimum would be :-   ( all guesswork of course)

2 X Ltg

1 X sockets ct to kitchen

1 X sockets to rest of house.

1 X cooker

1 X shower

 

[jas0n]

 I would usually run the smoke alarms from the nearest lighting circuit. And usually in a standard size home for power and lighting I would have on one rcd ground floor lighting, kitchen power and 1st floor power and another rcd would have 1st floor lighting and ground floor power.  This would be an altercation to existing wiring though.

recently working with another company when a complete new rewire was carried out in a home everything seemed to have its own mcb. Smoke alarms, heat detectors, 3 floors of lighting and power each on there own circuit and much more. A consumer unit had to be made up and it had so much just for a  normal 4 bed home.

Was this just over the top or really necessary.

Considering I'm qualified city and guilds lv3 in the past few months there is still so much to know on what is ment to be considered installed correctly.

 

[pewter]

I used to fit smokes on there own circuit.

My friend a fire alarm specialist spark argued with me about the scenario

'if you went away , smokes circuit tripped , battery's beeped until they run out, then you return unaware smokes are now out of action'

Though I think the lack of LED should be sufficient.

So I then changed to lighting circuit for a while.

Then recently someone pointed out a reg on safety circuits about not putting them on circuit with other stuff (540. X.xx. ish I think, I would look it up but I am trying to convince my 4 year to get to sleep with no success)

Now I can see sensible argument for both.

 

[Zeespark]

They ask that it not be put on a circuit with 13A socket outlets and a 30mA RCD protecting those sockets if I am correct Pewter, to get around this, I would have a dedicated lighting circuit with just the upstairs and downstairs hall way lights on plus the smokes, protected by a 3rd RCD just for those and your alarm circuit.

Andy Guinness

 

[batty]

I used to fit smokes on there own circuit.

My friend a fire alarm specialist spark argued with me about the scenario

'if you went away , smokes circuit tripped , battery's beeped until they run out, then you return unaware smokes are now out of action'

Though I think the lack of LED should be sufficient.

So I then changed to lighting circuit for a while.

Then recently someone pointed out a reg on safety circuits about not putting them on circuit with other stuff (540. X.xx. ish I think, I would look it up but I am trying to convince my 4 year to get to sleep with no success)

Now I can see sensible argument for both.

I suppose if you went away for a year this might be a problem. I can never understand why a circuit should trip out unless there is a fault surely if there is a fault on the smoke alarm wiring it will trip the lighting circuit out.

    I think I will carry on putting my detectors on there own circuit just remember certain lighting can cause problems with detectors if you read the instructions you will realise this.

 

[pewter]

They ask that it not be put on a circuit with 13A socket outlets and a 30mA RCD protecting those sockets if I am correct Pewter, to get around this, I would have a dedicated lighting circuit with just the upstairs and downstairs hall way lights on plus the smokes, protected by a 3rd RCD just for those and your alarm circuit.

Andy Guinness

What reg is that Zee?

I was thinking of 560.7 that someone pointed out to me.

Though reading it at 5:40am it seems more like a cryptic crossword.

560.10. Suggests I need BS5839 for a true answer

I'm with snoopy , I can't see a problem with smokes on there own circuit , preferably an RCBO.

 

[binky]

Own circuit for smokes was back tracked a while ago after changes to regs, can't remember the full argument anymore, but seem to remember Aico issueing guidance saying not to put on own circuit. Personally, for a new build I would wire hallway and smokes as 1 circuit, which seems to be how most new builds are done that I've seen recently. As for the rest, kitchen, gets its own ring, each floor a radila for sockets, lighting circuit per floor, although there is no particular reason for doing this in regs, especially when sharing RCDs, but then I like RCBOs