3 wire to 4 wire

[Unregistered]

I have a four wire plug on the side of my house 3 straight pins and a ground and I am wanting to hook a welder up to it. What do I need to do to hook the 3 wires up to a 4 wire plug.

Thanks
Jeff

[Wgoodrich]

First we need to know the welder and the amp rating of that circuit you want to use. Is this a wire welder about 20 amp 240 volt? Is this an arc welder about 50 amp 240 volt ? What is the amp rating of this 240 volt existing receptacle circuit?

Curious

Wg

[Unregistered]

The welder says 230 volts and 47.3 amps or something like that. the Welder is an arc welder. The Welders 3 wires are green, black, and yellow. Not sure on the amp rating of the circuit but the outlet looks like this one (see link) so I assume it is probably 50 Amp Service 3 straight with one round ground. --> http://www.homedepot.com/prel80/HDUS/EN_US/diy_main/pg_diy.jsp?CNTTYPE=PROD_META&CNTKEY=Products_2%2FElectrical%2FReceptacles&MID=9876&ProductOID=523260&cm_ven=1hd.com2msn&cm_cat=shopping&cm_pla=prod&cm_ite=prod
Thanks Again

[mdshunk]

Well, if the recaptacle is like the one you posted, then it is a 50 amp 4-wire range receptacle. It would be a little strange to have this on the outside of the house. Could this be something that someone had rigged up for an RV receptacle? When you post a picture of a range receptacle, and then say that it's on the outside of the house, red flags go up for me. Is it mounted in a weatherproof box made by Midwest with a embossed picture of a duck on the lid? Some testing and checks seem in order before jumping into this with both feet.

First, I'd get a tester (multimeter or the like) and put it in the two side slots and see that you have about 240 volts. Then, take the tester from the middle slot to each of the two side slots and see that you have 120 volts between the middle slot and each side slot. Then, place the tester in and start turning off breakers. Check to be sure that the breaker feeding this receptacle is actually a 50 amp breaker (will say 50 on the handle). If all of these things check out, the only other thing you have to do is find the cable feeding this receptacle (if you can) and verify that it's at least #6 gauge wire. Should be written on the jacket of the cable.

If everything checks out from the above paragraph, then you're on your way to changing to a 3 wire setup. You currently have a 240/120 volt grounded setup, and you only need straight 240 grounded. For the new setup you'll need to put the two hot wires (likely red and black) on the two "slots" of the new 3-wire 50 amp receptacle. The ground wire (likely bare) will go on the "hole" of the new 3-wire receptacle. The white wire (neutral) will be unused, and should be taped or wire nutted off. The white wire may remain connected in the breaker panel if you wish. Be advised that if this receptacle is exposed to the weather, by code it needs to be in a "weatherproof while in use" type of housing. Midwest is the only company I know of that makes these big honking receptacles in weatherproof housings.

[Unregistered]

it is a midwest box that is weatherproof housing with a 50 Amp breaker. So to hook up the replacement plug of the welder, if I have this right, the green goes to the ground post and the black and the white wire go to the sides correct. There are only 3 wires coming out of the welder. (The link to the picture was just to illustrate the arrangement of the recepticle

[mdshunk]

Oh... I get it. You don't want to change the recaptacle, you want to put a 4 wire plug on the welder to plug in to the existing 4 wire receptacle. Right? If so, then yes. The cord coming out of the welder should have a black, white, and green. The black and white will go to the side blades on the plug, the green will go to the round prong, and the middle blade will be unused.

You're in business.

[Unregistered]

Thank You that is what I needed to know.