Posted by David Sherman on Wednesday, September 19, 2007 at 12:21:27 :
In Reply to: Re: I completely missed that post... posted by Jerry in Idaho on Wednesday, September 19, 2007 at 00:31:41 :
I've had a lot of cords with pre-molded plugs overheat on steady loads that are well within their supposed rating. The wires are usually spot-welded to the pins inside the plug, but this seems to be a poor connection since the plug will often get hot enough to soften even while the cord is perfectly cool. On power tools, I always used the highest grade plugs I can find. If they're the sort where the wires have to be looped around the screw, I solder a crimp connector on the end of the wire instead. The newer kind where you insert the stripped wire in a hole and the screw turns a clamp down onto it are easy and safe, if expensive. Twist-lock connectors are routinely used in hard industrial settings, for connecting portable generators to buildings, and similar high-current rough-usage situations. But, I don't disagree that hardwiring is clearly safer and more reliable for anything.
I think part of the problem in this whole discussion is we're treating the "5 HP" compressor like it was a real 5 HP industrial motor. As I pointed out somewhere else, my "6.5 HP" compressor has a nameplate current rating of 15 amps, which is what counts when sizing the branch circuit. The "6.5 HP" or "5 HP" is a fanciful number created by a marketeer, rather like the "4 HP" vacuum cleaners and weed eaters Sears used to sell (which came with 20' of 16-gage power cord). Is suspect the real-world steady state HP of the standard retail "5 HP" shop air compressor is about 2 HP, possibly less, simply based on the physical size of the motor.
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