Hi, all!
I might as well add a little to this discussion:
Electrical appliances that use 110/220v (electric ranges, dryers, some but
not most 220V Air/Conditioner units) that use the neutral and have a 3 wire
plug are supposed to be grounded with a separate ground wire, screwed to the
chassis and to a good electrical ground. I'm not sure if this is required,
but it certainly isn't inspected (much, if at all).
I personally would not worry too much about the neutral failing to provide a
ground, but it is safer to use a safety ground for the chassis of whatever.
(The neutral and safety ground are common at the point of the mains power
entry-at least they should be; usually they are also common at a garage point
of electrical entry)
Now for the other thing I was just reminded of by a ad for a sears 5HP
oil-less compressor:
many of the compressor companies (starting w/ campbell-hausfeld) use a
different rating system for motor horsepower than used to be "standard": they
give "input" horsepower, not what the motor puts out. AC induction motors
are around 50% efficient, so a "5HP" motor (That draws 15a@220v or 30A@115v)
actually puts out 2-3HP. my compressor motor gives output horsepower (2HP)
and drfaws 12a@220v or 24a@115v, and has about the same airflow rating as a
"5HP" sears or Camp_Haus compressor. So I would use the airfloew ratings at
90PSI to rate compressors, not the horsepower ratings. (2 stage compressors
give much higher airflow ratings for the same horsepower input, and also wear
less/get less hot; If I didn't already have a single stage compr. I would get
a 2 stage.)
This was far too long winded, back to your normal shop-talk programming....
Scott M Ryan
PS: I once worked out the input horsepower on a campbell-hausfeld 5HP 60gal
belt drive compressor, and (according to the ratings on the plate) drew less
than 5HP in electrical power. (1 HP=746 Watts)
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