Looking at wiring in a small fan for an air cooler to my compressor so the
fan runs when the compressor does. Compressor is 240, fan is 120. Do I wire
in on one of the motor legs from the coil and just use a dirty neutral?
gotcha. and I didn't read your OP carefully enough to
realize what you are really asking about is how to run the
fan ONLY when there is a current draw on the motor. Do you
have a Grainger's catalog?
I don't think it's strictly to code, but the small current for a fan isn't
going to hurt anything being in the neutral. I'd do it, otherwise, you need
a relay for it...or a transformer (240 to 120), then you could connect the
fan housing to neutral.
Is that necessary, normally the large pulley on the compressor pump is
plenty. These things run hot and last for years running hot. A company
that I worked for had a compressor room with 8, 200 gallon compressors
running virtually non-stop all day long and the room was HOT.
Depending on the make and model of your compressor you may get away with
this mod I did on one some years back. I was able to change one of the
pulleys to a double pulley that I then used to drive a small fan rig device
thingy that I concocted. Use your imagination and you'll probably get what I
mean. Anyway the fan ran whenever the compressor did and helped to cool it.
But hot is not good. Shortens the life of the unit so even one that runs
for years can run even longer in a better environment Industrial
compressors are cooled with fans or outside cooling towers to keep
temperatures down. Air intakes are often outside to keep the temperature
down. Discharge air temperatures can easily reach 250+ degrees.
Don't go there, it's not worth it.
I could tell you a legal way to do it, but the cost of the equipment far
outweigh the benefits.
Find a 120V outlet and plug fan into it.
Forget to unplug it some night, so what?
By your own description, it is small, so power consumption is not an issue.
KISS definitely applies here.
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
What you are contemplating can be done correctly if the supply wiring
contains 4 wires including a separate ground conductor, You can connect to
any neutral along the path of the wiring that supplies a load that is
connected only to the opposite side of the 240 v. connection you use to
connect the fan. A word of caution. Usually the pressure switch for a 240 v.
compressor contains 2 switch connections, They are not always both used on
some units. Meaning that the motor is not completely disconnected only the
current path is broken, if this is so connecting a fan to the single switch
will result in the fan continuing to draw current through the compressor
windings from the opposite leg after the compressor has shut off. A small
fan would continue to run, possibly a bit slower. You could utilize the
second switch set to disconnect the fan and remedy this.
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