About to buy a few Kidde P12000 Smoke alarms.
The AC wired type, with both ionization and photocell.
Looked at their on-line instructions, and was surprised
to see that they say to install on circuits that are NOT
Anyone know the reason why ?
" Make certain all alarms are wired to a single, continuous (non-switched)
line, which is not protected by a ground fault interrupter. "
One reason that I can think of is that their products work better when
they have power and GFCI-protected circuits are more likely than ones
that are not to be continuously powered. A minute circuit fault that
will never be noticed in a regular circuit may well kill one with a GFCI
-- exactly what you want most of the time but not so with an alarm.
That's probably to avoid the risk of electrical leakage to ground on
that circuit, like from an unoticed roof water leak finding it's way
into an electrical box, could trip the breaker and render the smoke
alarm system useless, without your being aware of it.
For the same reason, it's probably wiser to put the smokes on their own
breaker if possible. It'd be a fine mess if another appliance on the
same circuit as the smokes decided to overheat, catch fire, and then pop
that circuit's breaker before the smokes went off.
Kidde does seem to be out of touch with the current codes. They do
still sell AC only detectors and they don't seem to understand the
code requires smoke detectors in bedrooms to be on AFCIs (which
provide GFCI protection at the 30ma level)
On Thu, 24 Feb 2005 21:58:30 GMT, Here to there
On Fri, 25 Feb 2005 04:53:18 GMT, Takoma Park Volunteer Fire
Yeah this is a good idea, and so much so, I think it's in the
electrical code somewhere. Like it says don't run a dedicated smoke
detector branch, something else needs to be on it.
Have to check, since I can't remember where in the NEC it is, I might
be mistaking this for boca, or something else.
tom @ www.ChopURL.com
I believe code addresses it.
GFCI's are oriented to protecting personel from electricution(from
conductors to ground). The risks of nucience trip, vs electrical
danger is too great. No need to risk losing a whole house's smoke
detectors because of a flawed gfci.
GFCI's can have nuisance trips. Even a thunderstorm nearby can sometimes
trip a GFCI. This could greatly shorten backup battery time for the smoke
detector, or even cause complete failure if the circuit isn't promptly reset
before the battery dies. The smoke detectors should also be on the same
circuit as often used lighting to make it very obvious if the circuit is open.
For similar reasons, it's not a great idea to put a refrigerator on a GFCI
Not exactly the same situation, but a similar principal:
The US Electrical Code has exceptions for overload protection for fire
pumps in residential appartment dwellings. The theory is that you
want power to be supplied to the fire pump no matter what, even if it
burning up do to an overload.
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