View Full Version : Electrician help - mains smoke detector
Very random for a bike forum but this place is a wealth of information!
Just replacing our old smoke detectors which had passed their replacement date (Aico Ai151) for a couple of Aico Ai141's.
The wiring of detector 2 looked like this previously:
http://i7.photobucket.com/albums/y258/saul_uk/IMG_1276.jpg
Problem is, the old detector had no ground and a battery -'ve terminal, the new ones have a ground but no battery -'ve. Instead of having 2 wires coming out of the one block for Neutral + Battery -'ve, I've now used neutral only and used the ground which was previously unused.
Only thing throwing me off is the black cable running into detector 1??:
http://i7.photobucket.com/albums/y258/saul_uk/IMG_1277.jpg
Could someone in the know confirm this is right (or wrong!) before I flick the fuse box back on!?
thefallenangel
23-12-12, 04:57 PM
Black cable looks like it could be a link cable between the alarms?
http://www.aico.co.uk/how-do-i-wire-hard-wired.html
The yellow wire is the interconnector as there's only one of them going into detector 1. That link does help mind - I think the black wire is the neutral to detector 1 and the blue wire neural running to detector 2.
Doesn't explain why the battery -'ve and neutral were wired to the same terminal on the old plug though?? :S
Is it because the old smoke detector had a rechargeable battery??
andrewsmith
23-12-12, 05:36 PM
On a large size fire alarm systems its 3 wire MICC rated Cable is similar to twin and earth
Earth, Neutral (comms) and 12v (Green/Yellow, Brown, Blue. Colours might be wrong).
Looking at the wiring schematic
http://www.aico.co.uk/images/stories/Images_-_Optimised/Contractor---HDIW-Alarm-Diagram.jpg
I think your missing a wire as you should have 4 in the back Earth, 12v, Neutral and link (black)
thefallenangel
23-12-12, 05:37 PM
The blue to earth is whats worrying me why have they been split?
Because the old detector had no ground, this one does so I've earthed it?
The black cable in this system is the yellow one in the schematic. I'm happy with the interconnector, more concerned as to why there's a black cable running into the neutral terminal on the box!
andrewsmith
23-12-12, 06:12 PM
If in doubt pull some new cables in. Black used to be an IEEE Reg color for Neutral (with red as live). Earth has been required for a good few years on most things
Looking at that wiring it looks a bit dubious, is it 230v or a 12v system?
230v. I spoke to a friend of mine who's an electrician and he said it looks right but just do away with the blue wire I'm using to earth as it's blanked off already - does say in instructions earth isn't needed, it's just in case you've got a stray wire.
The colours are pre 2004 so I think you're right, they just used a black neutral to detector 1 and then ran a blue neutral to detector 2. The old detector wiring threw me but it was rechargeable so think it called for slightly different wiring (i.e. needed battery -'ve to feed to neutral to complete circuit). This only calls for 3 wires, neutral, live and interconnect and I've sorted them.
I'll give it a bash - at least I know I've not got any neutral / live crossed.
Tested and flicked the mains on, working as they should and interconnected so think this is sorted. Thanks for the input guys
Specialone
23-12-12, 07:42 PM
Not all things require earth, double insulated stuff doesn't generally.
Do mains ones need replacing then? Didn't know that. How do you know when to replace them?
thefallenangel
24-12-12, 05:25 PM
Sticker on them normally.
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