Circuit/breaker size for new compressor?

[Tony Sade]

I'm buying a new compressor to run nail guns, staplers and and an HVLP conversion gun, and for filling up tires and such, and am wondering whether the circuit I have is sufficient. Wire is #12 copper connected to a 20A breaker. The line technically isn't "dedicated" to the compressor, but the only thing connected is a 4-outlet box. Nothing else will be running while the compressor is in use.

The compressor, a 3.5 hp, 20 gal. Quincy, is 115 volts, and will peak at 15 amps, I'm told.

Am I good?

Thanks,

[Todd Bin]

#12 is fine if it peaks at 15 Amps. #12 can handle 20 A.

[Gary McKown]

If it is truly a 3.5 hp motor, that would be a lot more than 15 amps at 115 volts, especially at startup. Sure it isn't 220 volts?

My "1.75 hp" compressor draws 13 amps when running, probably more at startup. I have one GFCI circuit that will not power up the motor, but on all other non-GFCI 15A or 20A circuits it works just fine.

[Paul Simmel]

>>> The compressor, a 3.5 hp, 20 gal. Quincy, is 115 volts, and will peak at 15 amps, I'm told.

You're good.

[Tom Veatch]

... 3.5 hp, 20 gal. Quincy, is 115 volts, and will peak at 15 amps...

Well, 3.5hp, 115v, and 15a, cannot all three be correct. Even at 100% overall efficiency, 3.5hp output will require 22.7a at 115v.

If the motor's full load amperage (FLA) is 15 amps as implied, then any 20a circuit will handle the load - assuming there's no other significant simultaneous load. Startup transient or surge isn't a factor since the circuit breaker will tolerate the start transient overload long enough for the motor to come up to speed in normal operation.

[Brad Sperr]

The compressor may have a universal motor that's rated on is stall or "peak" horsepower, in which case I would go by the amperage rating on the motor plate for deciding the protection you need at the breaker.

[Curt Harms]

I've seen "4 h.p."+ compressors running on a 120 volt 15 amp circuit. Didn't know Quincy would play that game though.

[Chris Padilla]

You're good; plug in and forgedaboutdditt.

Remember that circuit breakers protect the wiring in the circuit--not what is plugged into the circuit.

#12 with a 20 A breaker at 120 V is the max for the wire and breaker and voltage.