I have a small sub-panel with 30 amps coming into it. I have had my used air compressors motor changed to one that draws 13.5 amps. The 15 amp circuit breaker still trips though the unit was rebuilt professionally.

There are only six 15 amp circuit breakers available to me and 5 are used. They are "Square D" and I am asking if a 20 amp breaker is the same physical size as a 15 amp breaker in the Square D. Am I correct to assume then that I would wire a receptacle with 12 gauge wire? Can I use 12 gauge wire from the circuit breaker to a regular rectangular box with a normal 3 prong plug and a normal receptacle like one sees in a house? Or does it have to be some sort of special plug and receptacle?

Thank You, David

Yes. Just use a 20 A receptacle too.

You might want to use 12 AWG wire on the compressor and use a 20 A plug and cordset.