Wired Smoke Detector False Positive

I did a home inspection yesterday and when I tripped one of the GFCI outlets in the bathroom all the smoke detectors went off. (It did this once and I could not get it to happen again on purpose). The smoke detectors are wired into the electrical system and I was wondering if this is a common false positive or signs of a greater problem??

Is there any chance they were on the same circuit as the GFCI?

I have no idea with out further testing.
In this case I would just write it up as you did here and recommend the get it repaired immediately by a qualified person .
In Canada all homes now require CO detectors also.


Thats what I did but I just never encountered that and yes I believe they may have been on the same circuit they were in adjoining rooms.

If this is the case of them being on the bathroom GFCI circuit:

Per NEC, a 20A single circuit can service EVERYTHING in ONE bathroom, or just outlets in ALL bathrooms.
There is no other provision; Nothing else is allowed to be attached to that circuit.
Hard-wired smoke alarms is a recent enough requirement, so I doubt this is an old “grandfathered” installation.
I would definitely call it out.

As a side note, smoke alarms do not have to be on a dedicated, separate circuit, but they do not belong on a bathroom receptacle circuit per above.
It is also a good idea to have the alarms on the same circuit as something noticeable, such as lights in a frequently used area of the house, that way if the breaker trips and they lose power, the HO will know.

More to the point on what I said…
My theory:
Alarms were on the GFCI bathroom circuit.
After GFCI trip test, they lost AC power, making them cut over to battery backups. Such cutover triggered a a false alarm in one, thus making the rest of the alarms go off. Because this is an accidental and unintended condition, it is not easy to replicate, but I bet if you did it 100 times, it would happen once or twice.
At the very least I would report that they don’t belong on the bathroom receptacle circuit.