Smoke alarms

[andemz]

Hi there. can i run something by you

I'm considering smoke alarms. Just wanted to check something out. At the electrical shop today the bloke behind the counter states that you have to come out of the consumer unit with 1mm T & E to the first smoke detector and then from the first one to the second smoke detector and all subsequent smoke detectors you should use 1mm 3 Core and Earth. Does this sound right. I take it that a 6 MCB way in the consumer is right.

Thanks in adavnce

 

[andemz]

Here is the instruction manual as taken from TLC. I can't see where they are using 3 core and earth http://www.tlc-direct.co.uk/Technical/DataSheets/Kidde/Man_AC_Installer.pdf

See what you think

 

[breezer]

not true at all.

it depends on make of detector, the 3 core and earth, is to supply the detecors (and earth, but how you earth a plastic detector) the 3rd core is to inter connect them so that if one goes off they all go off

6A mcb is correct

all that said, you can wire each one individualy (if it has a back up battery) to the nearest light

in short depends on make of detector

 

[andemz]

Thanks breezer.

I think i would prefer it to be on it's own MCB non RCD. So here goes.

CU-----(1mm T & E)-------O=====(3 Core & E)=====O======O

It's the stage between connecting the cable to the detector and then start using the 3 core that i get confused on

 

[breezer]

It's the stage between connecting the cable to the detector and then start using the 3 core that i get confused on

why?

as your drawing shows, L & N to first, L, N, SW L* to 2nd etc

* it may not be switched live, but a "signal"

 

[andemz]

as your drawing shows, L & N to first, L, N, SW L* to 2nd etc

* it may not be switched live, but a "signal"

This is as much about learning as anything elese breezer can you talk me through it.

1mm T & E Brown= (Live) Blue= (Neutral) Earth =Earth. They would connect to 3 core and Earth.

Would it be possible for you to show how this then is connected from T & E to 3 Core....

 

[breezer]

Would it be possible for you to show how this then is connected from T & E to 3 Core....

wait untill you have detectors, its nice of you to ask, but you are worrying too much

twin to first detector, 3c & e to 2nd etc

3rd core will connect to ? terminal on each detector ONLY

 

[securespark]

If using a modern MK board, a 3A MCB is OK too.

 

[ban-all-sheds]

I think i would prefer it to be on it's own MCB non RCD.

The point about it being on a lighting circuit is that if the MCB trips, you know abut it PDQ, and will sort it out immediately, rather than live in darkness.

If the smokes are on a separate MCB, that could trip and you might not notice.