I recently rented a house at the shore. The house is about a year old. In the bathrm. there was a GFCI receptacle and everytime the hair dryer was plugged in and turned on hi the smoke detectors would go off. It was instantaneous turn on hi they would ring. Turn off the hair dryer and they would stop. Any ideas what is causing this?

Smoke coming out of the hair dryer?

No its instantaneous and the smoke detector is 10-15ft away from bathroom

Probably the smoke detector is hardwired, and it is either on the same circuit as the bathroom outlet, or it is sharing the same neutral. If it alarms with low voltage, then it is the same circuit. If it alarms with high voltage, it is on the shared neutral circuit.

Just guesses on my part.

Larry