Is there any rule which states not to run 120V wired smoke alarms from
a subpanel? I could see someone saying that the breaker to the
subpanel might flip leaving the smoke alarms with no AC power. Is this
a real concern addressed within the NEC or fire codes? Or can I just
run it off the subpanel and forget it because code doesn't address the
Thank you for your time and energy,
William, the importance of a smoke detector is that it be functioning 24-7.
If it were installed on a dedicated circuit from any panel, it could
inadvertently be turned off. If it were installed on any general lighting
circuit, most likely you would know if it were turned off by the other
things that went off with it
Do they ever get connected between the main and the bus bar? In other words
no breaker? I'm not suggesting anyone do that. I think mine might be hooked
up that way. new house. If it is that way it was done that way for a reason
and not on accident. I learned this when I was trying to silence a nuciance
alarm (Having some new pipes soldered and kept tripping). I switched off
every breaker, one at a time, and the alarm never went off! Switched the
main and it DID go off. Strange!
The only piece of equipment I am aware of that comes off before the mains,
is a fire pump.
Please send pictures of any wiring you have in the panel that is ahead of
the main breaker.
Me thinks you just missed it and then the detector cleared itself. New
homes have a battery backup in every detector as well as the 120v power.
My understanding was that they are to be connected to a branch circuit
breaker that also feeds lighting or other circuits where if the breaker
tripped you'd notice nearly immediately, e.g. kitchen lights, dining room
Note too many breakers are not rated for multiple wires under the ;oad
terminal, if this is the case than it implies a junction box will be
required somewhere downstream (perhaps adjacent to the breaker panel,
perhaps the nearest alarm, etc.) where the alarm feed branches out.
I have seen 120V hardwired detectors w/o as well as w/ battery backup,
though clearly the latter is to be preferred, and local code requirements
might you to the latter anyway.
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