Author Topic: Smoke Detectors. Mains Interconnected, battery backup  (Read 4628 times)

Offline nim

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Smoke Detectors. Mains Interconnected, battery backup
« on: August 31, 2008, 11:48:33 PM »
I have 8 Smoke Detectors. Mains Interconnected, battery backup. they are conncted by 1.5mm T&E as per the manufacturers instructions. The earth wire is the interconnecting wire.  They keep giving off false alarms. They have no hush button so I have to run around, remove the battery and then flick the fuse at the fuse box. It has got to the point where I have disconnected the interconnecting wire which defeats the object of them being interconnected. Disconnecting the interconnecting wire has revealed rogue detectors but when I have removed the rogue and reconnected them it still doesn't solve the problem because after some time another one develops a fault and the cycle starts again.

Does anyone know of a decent reliable replacement which won't cost a fortune or do I have to pay a fortune to obtain reliability? If paying more guarantees reliablity then thats what I will do.

Thanks in advance.

Offline Galeon

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Smoke Detectors. Mains Interconnected, battery backup
« Reply #1 on: September 01, 2008, 12:09:57 AM »
The earth or cpc should only ever be used as an earth , so it should be  served with a 3 core and earth cable to start with . The arrangement you have is no different than using the earth as a strapper on 2 way lighting , a complete no no.
You will also find the cpc conductor is slightly smaller than the conducting cores.
Now I know the cpc (earth) is the interlink and the detectors may be double insulated , but can you confirm that the wiring is telling you to use the earth , which I find very strange.
Personally I don't rate any of these , and as you have 8 I would look into having a proper small commercial system .
Its time to make a counter attack !

Offline nim

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Smoke Detectors. Mains Interconnected, battery backup
« Reply #2 on: September 01, 2008, 12:33:49 AM »
The earth isn't connected to the earth at the fuse box or anywhere else, but yes the manufacturers instructions advise using 1.5mm T&E with the earth as the interconnector.

I have been told that some other domestic systems use 3 core and earth. Because I have used T&E I was looking for detectors to replace using the same wire as oherwise I would have to completely rewire with carpets and floorboards up.

Also, it's a house. Wouldn't a small commercial system be OTT and isn't there a decent domestic system  out there using T&E or am I expecting too much or did I just buy the wrong system in the first place and have to rewire and replace?

Offline Galeon

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Smoke Detectors. Mains Interconnected, battery backup
« Reply #3 on: September 01, 2008, 07:59:30 AM »
The boys will probably post a good alternative , by the way I take it that these detectors are suitable for the risk ?
Its time to make a counter attack !

Graeme

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Smoke Detectors. Mains Interconnected, battery backup
« Reply #4 on: September 01, 2008, 05:30:33 PM »
Quote from: nim
The earth isn't connected to the earth at the fuse box or anywhere else, but yes the manufacturers instructions advise using 1.5mm T&E with the earth as the interconnector.

?
never heard that one before.  always use 3 core and earth and the earth as a cpc.  


if you are happy to re-use the cabling then any m.o smoke alrm will work but use one with a hush button.   http://www.aico.co.uk/smoke_160.htm

or use ones with the I/C is done by radio link. That way you can revert the earth wire back to what's it should be used for.  http://www.aico.co.uk/smoke_radio.htm