Fire Alarm powering Attic Fan: Legal?

Hello!,

I live in WA, USA, and had some people install an attic fan. They hooked it up to a fire alarm, as a power source, but since then:

• The fire alarm will randomly go off on its own, and it is that single fire alarm.
• This will happen on days that are especially rainy, windy, or lightning storms (especially lightning storms).

My concerns are: Is this a fire hazard? Does this affect the fire alarms to detect an actual fire?

Also, is it custom to see the permit before/after work is done? (I don't think I ever saw the permit.)

Thank you.