4cylndrfury
4cylndrfury Dork
12/16/09 2:08 p.m.

I recently found myself the proud new owner of a salvaged electric motor: 1/7 HP, 3450RPM, 115v, 2amp, 60hz, single phase

The problem is the cord has no ground wire, just a black and white (poer and ..other/negative?). I think it was “grounded“ by being fixed to the machine it was powering.

How do I go about grounding this motor if its no longer part of said machine? i.e. I want it to stand alone and power a small pump designed to operate at 3450RPM.

Dr. Hess
Dr. Hess SuperDork
12/16/09 3:21 p.m.

Put the power cord's third (ground) wire on a bolt/screw attached to the motor case (scrape paint off first). If something starts smoking, you probably shouldn't-a-been messing with that thing anyway.

4cylndrfury
4cylndrfury Dork
12/16/09 3:26 p.m.

does the big aluminum mounting base of the motor count, or do I need to use the steel housing? I know Im asking pretty generic questions.

Dr. Hess
Dr. Hess SuperDork
12/16/09 3:44 p.m.

The best place would be to the steel motor housing. The ground is there to protect you incase something inside accidentally connects with the motor housing. Now, the aluminum mounting base is probably pretty well connected to the steel motor housing, but if it was my life on the line, I'd find a way to connect it to the motor housing. Look inside the connector plate thingie. There's usually a screw into the housing for just such a connection.

4cylndrfury
4cylndrfury Dork
12/16/09 3:46 p.m.

indeed there is! thanks sir

Tetzuoe
Tetzuoe Reader
12/16/09 3:55 p.m.

Sorry about the humongous picture, but preferably look for something with the ground symbol:

cwh
cwh SuperDork
12/16/09 4:52 p.m.

GENERALLY the black indicate hot, the white indicates neutral. Never trust that though. At an outlet with black and white wires, you should read zero volts from white to ground, 120 vac from black to ground. But I have seen way too many wired backwards. Just think that if you touch the black wire, your burned finger will be crusty black. The older the house, the more likely it will be backwards.

billy3esq
billy3esq Dork
12/16/09 5:38 p.m.
cwh wrote: Just think that if you touch the black wire, your burned finger will be crusty black.

Another mnemonic is that the neutral color (white) is the neutral wire.

However, as others have noted, that's just an opening assumption. Don't bet anything you can't afford to lose on it.

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