Wiring smoke alarm

Kemik · 12 Aug 2017 at 17:37

Hi guys,

When I moved in I installed two Nest Protect smoke alarms. The guide was easy and I put the wires where told. Now I need to remove them and, while I took photos of the downstairs wiring (Brown - Live, Black - IC, Grey - Neutral), I didn't for the upstairs smoke alarm.

Does anyone have any suggestions?

The obvious one is green/yellow = Earth. I think black is the IC like downstairs but why are there two live and what is blue?

HardwareGeek · 12 Aug 2017 at 18:58

Smoke alarms are usually wired...

First alarm will have 1 x twin and earth + 1 x 3 core
other alarms will have 2 x 3 core
final alarm will have 1 x 3 core

Twin and earth is supplying the power to the alarms and the 3 core is then passing the power along to all other alarms plus the extra core for the interlink to make all alarms go off at the same time etc

looks like you just have 2 alarms

you just need to put....

First alarm
2 browns in live
blue and grey into neutral
black in to ic
2 earths in earth terminal

If you had other alarms 2-x you would...

2 browns into live
2 grey into neutral
2 black into ic
2 earth to earth

And final alarm

1 brown
1 grey
1 black
1 earth
etc

Kemik · 12 Aug 2017 at 20:15

Cheers mate! All sorted.

Pho · 12 Aug 2017 at 21:04

How much time did you spend swearing trying to get solid core wire bent into the terminals correctly?

I installed some of those AICO alarms around my house a few months back using 1.5mm solid core wire - what a pain!

Kemik · 13 Aug 2017 at 10:01

Pho said:
How much time did you spend swearing trying to get solid core wire bent into the terminals correctly?

I installed some of those AICO alarms around my house a few months back using 1.5mm solid core wire - what a pain!

The worst bit was trying to get the terminal blocks off the old Nest setup. I gave up and cut the wires in the end.

robj20 · 13 Aug 2017 at 13:12

Push fit on the new ones. Shame the wire they give you is so short. I just connect mine off the lighting ring.

ZG002 · 13 Aug 2017 at 15:26

Easy to install with practice. There's a knack to it.

Kemik · 13 Aug 2017 at 15:36

robj20 said:
Push fit on the new ones. Shame the wire they give you is so short. I just connect mine off the lighting ring.

Easy to put in. Try taking them off!

rexehuk · 13 Aug 2017 at 18:18

robj20 said:
Push fit on the new ones. Shame the wire they give you is so short. I just connect mine off the lighting ring.

I don't get dedicated alarm rings. I'm doing the exact same cause in my eye wiring into 3 separate lighting circuits is better than a single fire alarm circuit!

Got my new nest protect sitting here, can't wait to fit it.

ZG002 · 13 Aug 2017 at 21:53

They are normally on the same circuit because they are hard wired with the IC, one goes off they all go off.

That link is starting to become more commonly wireless though.