What size circuit for a 5 HP air compressor?

[Ole Anderson]

The difference is; a motor seldom produces more power than is needed at any given time. So an electric motor capable of 5 HP will almost never see a 5 HP load.

Two notable exceptions being dust collectors and air compressors. They may very well be run near full load whenever they are operating, unlike your saw which sees a full load only when you are ripping heavy stock.

[Michael W. Clark]

The Baldor 5 hp 1ph motor on my Oneida DC takes 19.5 amps @ 230V. I have it on a 30 amp circuit, and it runs fine. Most circuit breakers will allow a brief overcurrent (up to a certain amount) before they trip to allow for motor starting issues like this. That being said, a compressor may be a harder starting load than a dust collector.

Kirk

The Baldor site has a 5HP Premium Efficiency single phase for ~19 FLA. It looks like most of the other motors that are not premium efficiency are in the 22-23 FLA range, seems like you could still do a 30A circuit.

Irregardless, assuming the plug on the OP is original, I would plug it into a receptacle that matches and enjoy it. If its been added after the fact, then ???

[Matt Marsh]

Michael,

If the manufacturer lists a minimum circuit size, then the NEC considers that acceptable. If the manufacturer does not list the minimum circuit size, then you must size everything according to article 430. If you have a motor that is not thermally protected, and the manufacturer does not list the minimum circuit size, then you must begin your calculations using the values given in the appropriate article 430 tables for your type of motor. At that point, it doesn't matter what the nameplate of that motor lists for FLA, you have to use the value given in the appropriate table. For the grizzly 5HP saw, I don't know for certain, but I have a hunch that the motor is really a tad smaller in actual HP than a true 5HP model. (hence the reason for the slightly smaller minimum circuit size).

The FLA values in the article 430 tables are generally an amp or two higher than most nameplate ratings. But they are always very close, even for models with themal protection.

[Joe Jensen]

I have a 5HP Quincy on a 30 amp 220V breaker and I have a Powermatic 24" Dual Drum sander with 5HP motor on a 30 amp 220V circuit. I also had a 5HP Saw Stop Industrial on the same...joe