Smokes & Ceiling Fan

[Little Bill]

Got a call from a customer saying his son added one smoke alarm and replaced one in his basement. There are two old (25yr old) smokes upstairs that interconnects with the basement ones. He also added a ceiling fan in the basement. He's says that when he turns the ceiling fan on it sets the smoke alarms off.
He says they turn off the breaker and the alarms stop. Then when he turns the breaker back on, with the fan on, the smokes alarm again.

I don't know if it has any bearing but I told him to replace the two old ones with the same brand as the new ones. Regardless of whether it fixes the problems, with the old ones that old they certainly need replacing.
Any thoughts as to whether the fan has anything to do with the problem?

 

[augie47]

I would be suspect of the "interconnect" conductor. Perhaps he connected the fan to that conductor.
(I have seen smokes interconnected with the equipment ground)

 

[Little Bill]

I would be suspect of the "interconnect" conductor. Perhaps he connected the fan to that conductor.
(I have seen smokes interconnected with the equipment ground)

I told him to change the old smokes for new and if that didn't help he could call me. If I go I will check that.
Is the interconnect wire 120V?

 

[augie47]

I told him to change the old smokes for new and if that didn't help he could call me. If I go I will check that.
Is the interconnect wire 120V?

No.. it's just a "bias" voltage to trigger the electronics.

 

[Little Bill]

No.. it's just a "bias" voltage to trigger the electronics.

Then if the wire was connected to the fan, I don't see how it could run.