I have a mains powered smoke alarm in our hall which, to be honest, I had forgotten about!
I have two battery powered smoke alarms elsewhere in the house which I am about to replace, as they are at the end of their stated life. The new units I have sent for have a guaranteed life of 10 years including lithium batteries.
I was also going to replace the mains powered unit, but it occurred to me that a similar replacement would also have a guaranteed life of at most 10 years, and would cost at least as much as the battery powered ones I have ordered, so why mess about with another mains powered one?
Now for my question. If I remove the mains powered unit, what do I do with the trailing wires? I assume these lead from a transformer somewhere in the loft (it’s a bungalow) and that is likely to be attached to the nearest light fitting. If so, the loft is boarded in that area, so I’m going to have to remove floorboards to get at it.
I’d prefer to remove the lot: transformer and attached cables. Is there an easy way of doing that, or is it safe just to leave the lot in the loft, still attached to the mains supply?
The mains powered smoke alarms are exactly that - mains powered - they will have a mains feed directly into them, often as you say from a nearby light fitting (although they can be from a dedicated circuit)
Thanks. Useful information.
If I want to use a new battery-powered smoke alarm in its place, I shall have to make good the mains wiring.
I seem to have two options.
I could open the nearest light fitting and hopefully find the connections, but one will have to be to a permanent live and the other to a neutral. If they’re not there, who knows where the connection will be?
The other option would be to make safe the power supply to the smoke alarm and leave them in the ceiling. If I attached chock blocks on them, would that be acceptable do you think or is there something else I’d have to do?
If you are not a qualified electrician - call one. Please!..no matter “Mr Fixit” you think you are…(I tend towards that myself) DO NOT mess with mains electricity. A guy in my neighbourhood prided himself on being good at “home wiring”. He was not in any way qualified as a sparky. He had a house fire which was determined to be because of his amateur electrical efforts. His insurance was void because of it and he had to fork out more than $50k for repairs. Just a thought.
Thank you both.
I may decide to replace the mains powered smoke alarm with another of the same type. That would be not only the safest, but also the easiest option!
Actually, although I’m not an electrician, I have done similar simple jobs: replacing sockets, light switches and lamp fittings, etc., and I haven’t killed myself yet.
Of course, there’s always a first (and last) time!
You could buy a switch patress ( plastic back box ) and a blanking plate and remove your smoke alarm and just use choccy blocks inside the patress, as long as it’s not too unsightly
If it’s not on it’s own circuit ( which I would’ve thought it should be) it would depend on what type of circuit was used, it might go back to a joint box in the loft, or taken from the nearest light
I presume that if the mains fails the alarm will go off as a backup battery is included
I can’t see any problem . just turn off the electricity at the mains first of all.
then you can just cut off any feed to the transformer if the feed cables disappear.
Next insert the feed cable ends into a terminal block as below
and finally wrap with insulating tape.
If you then want to replace with another mains powers unit then the connection point is readily available
However first of all I would find out in consumer box which fuse is protecting the smoke alarm by process of elimination.
If the consumer box is labelled as it should be, it will at least enable you to find out which circuit it is on, (power or lighting) and which one. Then you have an idea of where to start looking for the connection point.
One useful bit of kit is an electrical tester to find out if the wiring is live or not.
This is mine, many years old (must be at least 30 years old if not older) but works right across the power range
Mains-powered smoke alarms don’t have separate transformers, everything is in-built. You would be well advised to replace this and not rely solely on battery operated types. You can fit battery types as an addition to a mains powered detector if there aren’t the requisite number of mains-operated smoke alarms installed, not installed close enough to a bedroom, or there is adead area that the smoke alarm can’t reach. I’ve seen this in numerous properties where the number of detectors has been reduced as cost-cutting exercise. If your mains-powered detector is in a hallway, you should replace this with an optical type with battery back-up. I only fit AICO smoke alarms - this one in particular.
It is reasonably priced (£23 for ten years is a drop in the ocean) and easy to install. If no interlink, it’s a simple live & neutral connection to the inbuilt connector block.
You presume incorrectly. The battery is there to maintain the smoke alarm should the electricity go off for some reason.
Incidentally, old-style connector blocks aren’t recommended any longer, they’ve been replaced with Wago style push-fit connectors and cage clamps. ALL connections used to join cables together should be enclosed within a suitable enclosure such as a choc-box used for lighting circuits, or a WAGO box used for socket/cooker circuits.
The push-fits and cage-clamps can be re-used if needed, the cage clamps in particular. They have clamp and release levers for the purpose. Further, they can be used where access to cable connections is limited or non-existent. A fit and forget solution.
The one that appears above looks even better. It includes a CO alarm for £20 with 10 life as well.
It might be an easier option just to replace the mains-powered alarm with one of the above. Just a matter of rewiring, which I’m sure I’m capable of.
The other two alarms I’ve already sent for are battery-only, but have a guaranteed life of 10 years (lithium battery). They’re from Safelincs, a fire-service recommended company, so I think I’d trust them. I test them regularly anyway.
Incidentally, Safelincs is the company I got our ‘water-mist’ (brilliant invention - can even be used on electrical fires) fire extinguisher from.
Tut, tut.
