220 to 110???

[shinnlinger]

Hi,

I recently acquired an old beast of an air compressor.  I already have a big boy compressor so I don't need this unit, but it has a 2 horse Dayton motor that might be useful.  It works on 220, but the motor says it can be 110.  So how do you swap it over?  The motor currently has 2 hots and a ground going to it I don't see how I would put a neutral to it, unless I just run a neutral to one of the hots, but that seems weird to me.

Any ideas?

Thanks.

Dave

[mrnero]

usually there is a diagram on the back side of the electric cover on the motor. Behind the electric cover, you have to swap two terminals for either 110 or 220 power supply. You will only need two power suppy (110 and 110) and a neutral side for 220 operation. If its wired up now for 220. it will be with two hots and a neutral, no ground wire required.

[DouginUtah]

Actually, 220 (really 240) does not have a neutral. Both legs are hot. A third wire would be a ground.

When converting to 120 V. one hot becomes the neutral.

Mrnero's first two sentences are basically correct.

[shinnlinger]

Doug,

Are you saying that I should simply connect the new 120 neutral to one of the old 240 hots and I will be good to go???

Dave

[Warbird]

I would consult the wiring diagram that was alluded to.  ;)

[Slabs]

Don't experiment!!!  If you can't find or understand the instructions for the voltage you choose to use then find someone who can.  There's a good chance of destroying a motor (and the building it's in) with improper wiring.  But then, consider running it on 220/240 if it's readily available especially if the motor is above the fractional horsepower range.

Good luck

[Gary_C]

Are you saying that I should simply connect the new 120 neutral to one of the old 240 hots and I will be good to go???

Absolutely not, unless you want to let the smoke out of that motor. Find the connection diagram for your motor. If you can't find it on the motor, go to the manufacturers web site and find it.

[beenthere]

Wondering how many terminal posts are in the motor (with numbers on them) ?

Some will likely need to be jumpered to get them on the single hot line. Neutral will need to be identified.

Here is an example of a wiring diagram (may do some more google'ing and find some more that fit your needs).

http://www.electro-tech-online.com/general-electronics-chat/9105-ac-motor-wiring-diagram-low-high-voltage-how-wire.html

[Magicman]

Absolutely not, unless you want to let the smoke out of that motor. Find the connection diagram for your motor. If you can't find it on the motor, go to the manufacturers web site and find it.

Normally there are 4 motor leads/terminals inside of the cover.  They should be labeled 1, 2, 3, 4.  When wired for 240, 2 & 3 are spliced together and 1 & 4 are your "hot" leads (going to your 240).  (The start windings are across 1 & 2.)

For 120 operation, 1 & 3 are spliced together and 2 & 4 are spliced together.  These then become your "hot" leads (going to your 120).  (The start windings are also across these leads.)

This information is only for reference.  The wiring diagram inside of the cover shows the way that your motor should be rewired.  Those with terminals normally have clips that are moved to strap the correct terminals together.

[DouginUtah]

Are you saying that I should simply connect the new 120 neutral to one of the old 240 hots and I will be good to go???

I'm not sure I understand your question. After you make the changes to the motor wiring (switching lugs to different terminals per the motor diagram), the cord will have one hot and one neutral. That gets plugged into a standard 120 V outlet which has a hot and a neutral.

Since you say this is a two HP motor I suspect it will not run on a 20 amp circuit--1 1/2 horse is usually the limit for a 20 amp circuit, so you will need a 30 amp circuit.