On Sun, 23 May 2004 02:02:33 -0400, Michael Shaffer
wrote:

This might be a stupid question...

The only stupid questions are the ones you should have asked, but
didn't. (The ones that result in blowing something perfectly good up
because you didn't know the right way to do it.)

but if I want to use my welder on a
GFCI outlet and have it use the GFCI do I have to wire the 3 prong
welder plug so it uses the neutral plug and not the ground plug? It's a
14-50R outlet.

I'll take an educated guess that the 14-50R 50A 120/240V 4-wire GFCI
protected receptacle you want to connect the welder to is there for a
portable spa, right? (That's the only reason to GFCI protect a
receptacle - the welder is inherently isolated by it's internal
transformer.) As long as the house and receptacle half is wired
right, you only have to worry about the load devices.

Check your welder's wiring schematics, or pop it open and trace it
out. The welder can not have any 120V parasitic loads hooked up to
use the ground wire as a neutral return wire (control boards, cooling
fans, work lights, gas solenoids, etc.) or the GFCI will see the
current imbalance and trip. Those loads need to be kept separate from
safety ground, and go back to the Neutral lug of the receptacle, and
to the GFCI breaker neutral load wire.

If the welder is wired for a normal 3-wire 240V receptacle, they
probably wired it to put the 'neutral' side of any parasitic 120V
loads on the ground wire. If it has any 120V circuits inside you will
have to open up the welder, install a new 4-wire range cord with a
molded 14-50 cord cap, and switch those neutral wires to the neutral
on the new line cord. Chassis ground (the green or green/yellow
wires) will be the only thing hooked to the ground wire.

(You might need to use a #10 or 1/4" screw and nut to bolt the
neutral connections together to the line cord white wire (and tape
them thoroughly) if the terminal strip inside the welder only has two
lugs and the grounds go to a screw on the chassis.)

And when you put in a dedicated welder receptacle in another
location, you don't need the 50A GFCI Breaker unless you plan to plug
your spa in there, too. They still aren't cheap (though they've gone
down a lot now that they're required for all new spas).

-- Bruce --
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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