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*72lb4x4* · 01-28-2009, 12:55 AM

Don't take those horsepower ratings too seriously... These calculations aren't that accurate because of the simplistic power equations but...

1HP=746Watts
5HP=5*746=3730W
Power measured in Watts=Volts*Amps
At 120V Current is 3750/120=31.1Amps on a 20A circuit which will work for a few milliseconds.
At 240V Current is 3750/230=16.2Amps on a 20A circuit which is fine.

Since many if not most decent size compressors are rated at 5HP peak, the people who make them are lying, or my use of a simple power formula is too inaccurate.

I'd guess that many 220/240V compressor motors are also rated high in HP.

The point is that when buying low end CH, Husky, Craftsman, etc. compressors, the HP rating is pretty meaningless. Look at the CFM at some PSI and duty rating percentage when available.

Just another point of view...

01-28-2009, 12:55 AM	#21
72lb4x4 Account Suspended Join Date: Jul 2006 Location: DFW Posts: 1,427	Re: For you guys with all the tools, need some input!! Don't take those horsepower ratings too seriously... These calculations aren't that accurate because of the simplistic power equations but... 1HP=746Watts 5HP=5746=3730W Power measured in Watts=VoltsAmps At 120V Current is 3750/120=31.1Amps on a 20A circuit which will work for a few milliseconds. At 240V Current is 3750/230=16.2Amps on a 20A circuit which is fine. Since many if not most decent size compressors are rated at 5HP peak, the people who make them are lying, or my use of a simple power formula is too inaccurate. I'd guess that many 220/240V compressor motors are also rated high in HP. The point is that when buying low end CH, Husky, Craftsman, etc. compressors, the HP rating is pretty meaningless. Look at the CFM at some PSI and duty rating percentage when available. Just another point of view...