On Mon, 24 Jun 1996, Jon N. LeChevet wrote:
Nick wrote;:
> At 20:22 6/24/96 -0400, Nickbk@aol.com wrote:
> >Fellow Shop Rats...
> >
> >I've seen a nut and a bolt, and I've even assembled/disassembled
> >one or two, BUT, my knowlege of electricity ends just after I throw the
> >switch, and it either works, or I call the electrical guy.
> >
> >So, I went out and got the 60 gal 5 hp "speedaire" ( same as a
> >Campbell-Hausfield) compressor and tried to wire it myself. Hey, how hard
> >could it be, right ? Only three wires on each end, piece-o-cake.
> >Wrong-a-mundo.
> >
> >I went out and bought some overkill size wire and a plug to go into the 220
> >outlet where the dryer sits in the garage. The instructions that came with
> >the plug, say that the white wire goes on the center
> >(weird angle) prong on the plug, which they note as "neutral" (?).
> >The instructions do not seem to care where the other two wires go (black and
> >green). So far, so good. Now I get into trouble. When I take the top of the
> >connector box off of the compressor, I find that the green wire is definitely
> >the ground wire on the unit. The two remaining connectors are marked + and -.
> >Does it make a difference which is + and which is -, and how do I find out ?
> >More importantly, is the prong that the white wire is connected to on the
> >plug called "neutral" really the ground ? Should this "neutral" be hooked up
> >to the green ground on the compressor, or should I wire all the like colors
> >together ?
> >
> >H E L P
> > Nick in Nor Cal
> >
> >
Jon replied:
> Whoa up! Black, white, and green says single phase (110 volt) wiring. The
> dryer plug is phase to phase (220 volt) and calls for white, red, and black
> wiring with green as the safety ground.
>
> Green -- safety ground
> White -- neutral (connected to the safety ground at the service entrance
> Black -- phase A
> Red -- phase B
> Blue -- phase C (only found in three phase wiring)
>
> + and - ??????? -- only used with DC, not AC, motors.
>
> Get someone who knows something about electricity to look at your hook-up
> since it sounds like you are about to hook a 110 volt motor up to 220 volts.
> Guaranteed smoke!!!
My 2 cents:
Yes, it is probably better to get somebody who knows his/her way around
220 to do this. But if you want to persist, at your own risk, of course,
I have some suggestions. I assume you do know that the compressor is
220, so it's not likely you are trying to wire a 110v motor to 220 v.
I suspect you have simply bought wire for the cord from the plug to the
compressor that is color coded for 110 volts. It is usable, but you
cannot blindly match colors. You may also have bought a plug that really
isn't a 220 volt plug, but instead a high current 110 volt plug. They
look a heck of a lot alike.
Look at the plug; it should somewhere have 220V stamped on it. If it
does not, and has 110V instead, that is one of your problems. A 110V
high current plug has one prong that is sideways, and can only plug into
a high current outlet that has one T-shaped female terminal. They look
virtually identical to some 220 volt plugs.
As far as I know, only three wires really truly have to go to your
compressors: two hot leads and a ground. There will be 110v between
each hot lead and ground, and 220 v between the two hot leads, which are
180 degrees out of phase. It matters not which hot lead goes to which
hot terminal.
Ray Gibbons Dept. of Molecular Physiology & Biophysics
Univ. of Vermont College of Medicine, Burlington, VT
gibbons@northpole.med.uvm.edu (802) 656-8910
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