Posted by David Sherman on Tuesday, September 18, 2007 at 22:09:06 :
In Reply to: Re: You're just.... posted by MoparNorm on Tuesday, September 18, 2007 at 21:42:03 :
A 5 HP motor, if it's an honest full-power American 5 HP will draw well under 80% of 30 amps, which means it's perfectly safe and legal on a 30 amp breaker with #10 wire. This is the same as a typical electric water heater or clothes dryer, and is no big deal to wire. So long as the wire is covered (i.e. inside a finished wall), it doesn't need to be in conduit.
The nameplate amps on the motors of my two shop compressors are 15 amps each, even though one motor is labeled "5 hp" and the other is "6.5 hp". They're honest about the amps but they're lying about the HP. Both are perfectly happy on 20 amp circuits with #12 wire (not far from the panel). It's not "cutting corners" when you use the gage of wire and rating of circuit breaker called out in the electrical code for the nameplate HP of your particular motor, and unless the run is unusually long, it's a total waste of money to run heavier wire than the load requires.
I'm sure you're joking about fires and craters, since all of us DIY mechanics routinely put explosive mixtures of gasoline and air into enclosed cylinders and ignite it. Repeatedly.
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