My circuit panel has a 20 amp breaker on the circuit that leads to the garage (I know this only by the little 20 on the head of the breaker switch). The garage has one 15A outlet, a few lights, and two garage doors.
I want to plug in a treadmill into the garage. The treadmill has a NEMA 5-20P plug on it and has a label that says it draws 18 amps at 120 V.
Is it safe to replace the 15A outlet with a 20A (NEMA 5-20R) outlet and plug the treadmill into it? I imagine running the treadmill at full velocity and opening a garage door might trip the breaker, but are there any other downsides?