[jons999]

The garage in my new house has the newer 4 prong outlet that i need to convert to 3 prong for my welder, plasma cutter etc. This is the only 220v circuit in the house so i don't need to worry about branch circuits, etc and the wire is sized to carry the rated load. I'm going to connect the 2 hot wires and neutral to the 3 prong outlet like they should be, but what do i do with the bare copper wire? Should i cap it off and tuck it in the box or should i ground it to the metal box? Also i know its frowned upon and maybe not even up to code to go back to 3 prong but i don't want to replace the cords on all of my equipment, i also have several very expensive 3 prong 220v extension cords.

Thanks,
Jon

 

[Jim Port]

A straight answer 40 volt receptacle does not use the neutral. It is two hots and the ground.

 

[joed]

Cap the neutral and connect the ground to the box and receptacle.

 

[Msradell]

I'm not an electrician but I have to ask the question it changed it from 4 prong back to 3 prong is legal under today's codes? Doesn't the code require all new 220 V receptacles to be 4 prong? If that's the case the OP may need to change the wiring on the receptacles for his equipment

 

[Jim Port]

Four wires are required for 120/240 receptacles like dryers and stoves. Straight 240 can still be 3 wires.

 

[joed]

They need to be installed to match your device. Dryers and stoves are the only things I know of that have an option to use three or four prong. Your welder has a factory installed three prong plug so the proper receptacle is the matching one.

 

[Speedy Petey]

I'm not an electrician but I have to ask the question it changed it from 4 prong back to 3 prong is legal under today's codes? Doesn't the code require all new 220 V receptacles to be 4 prong? If that's the case the OP may need to change the wiring on the receptacles for his equipment

This is what happens when people get their electrical advice from handymen and such. This part of the code has been screwed up so badly and perpetuated by folks who don't know what they are talking about for far too long.

Joe and Jim cleared it up. :thumbsup:

 

[lenaitch]

It sounds like the OP receptacle is on a 120/240 volt circuit. I'll leave it others to say if plugging a straight 240 device into it is acceptable. Regarding, circuit protection grounding should be connected as it's meant to.

 

[Speedy Petey]

It sounds like the OP receptacle is on a 120/240 volt circuit. I'll leave it others to say if plugging a straight 240 device into it is acceptable. Regarding, circuit protection grounding should be connected as it's meant to.

Yes, it seems he has a 120/240V circuit and wants to install a straight 240V receptacle. It is perfectly acceptable to cap off the neutral and just use the two hots and ground for this.

It would not be acceptable to remove the "4-wire" NEMA14 receptacle and install a "3-wire" non-grounding NEMA10 receptacle.