I had one which used the same beep for both! When the battery went flat it sounded continuously. Pretty stupid really, as if you were out it would be too dead to make a noise by the time you got back.
Sure. compressed air or similar.
In my case no, only two things set them off. Falsely. fat frying and visible 'steam'.
But they don't exist in the kitchen or bathroom, so that's a matter of keeping the door closed.
I was deeply grateful they DID go off when a log rolled out of the unattended fire into the hearth...
And, as fire officer in my business years ago, and as someone who has watched his brother in law's house burn to the ground, fought by a friends who happens to be the part time fire chief, there is no way I am taking mine out, even if it did NOT invalidate my house insurance.
Keeping the door closed is a hassle.
Good reason for not having unattended fires. It's why I use gas central heating. If that wasn't here I'd get a gas tank or use electricity. Flames in your house is BAD.
Oh. House insurance? Didn't think they had such as clause.
Something wrong with the alarm then...
Personally I use mains powered interlinked ones, saves worrying about batteries etc.
And if it's an electrical fire that blew a fuse?
They have internal rechargeables (which is a building regs requirement if they are powered from a dedicated circuit).
Rechargeables have a lifetime too.
ours are mains powered interlinked with battery backup on their own circuit (non rcd side of split consumer unit) so even if the mains fuse/mcb for the smoke detector circui goes there is still some cover but I cant remember how long for.
It's the other way around. A dedicated circuit needs no battery back up.
It was a pretty standard setup before the 17th edition came out.
Indeed - but so do smoke alarms, so as long as the former outlives the latter, there is no problem.
Yup sorry, my bad, missing a "not" there....
Building regs Approved doc B1 sections 1.17 - 1.18 for anyone interested.
Usually several months IME.
But only a fool would fit smokes without battery backup regardless of the dedicated circuit rules:-)
I still prefer to put the smokes on a lighting circuit, and with the 17th edition rules this would actually be powered by a RCBO not a RCD side of the CU.
That's a long power cut.
I thought it sounded a little silly, even for building regulations.
I know of a tosser that declared a building unsafe because there was 1 FOOT too far to walk to the nearest fire exit.
Are we still talking domestic installations?
Yes.
That's why the alarms on on a completely separate circuit.
And they beep if they lose power, for a while anyway.
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