The wiring for a 220-volt MIG welder is similar to the wiring for an electric clothes dryer in your home. The National Electrical Code (NEC) states that a new or renovation installation for a dryer has to be a 4-prong receptacle. The old code allowed a 3-prong receptacle. The 4-prong receptacle has its own ground, unlike the 3-prong receptacle, which used the neutral as a ground.
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Things you need
- 8/3 nonmetallic sheathed electrical cable with ground
- Utility knife
- Wire strippers
- 4-prong 220-volt dryer receptacle
- 220-volt double-pole breaker
Read the manufacturer's specifications to find out if the double-pole breaker will need to be 20 amp, 30 amp or 50 amp.
Run an 8/3 nonmetallic sheathed electrical cable with ground from the main panel box to the location for the welder receptacle.
Remove the cover of the new 4-prong plug. Inside will be screws and a wire connector. Push out the round knockout from the back of the receptacle and install the wire connector into the hole.
Push the 8/3 cable through the connector and tighten the connector to secure the cable. Screw the receptacle to a wall stud or wooden backer plate.
Remove the plastic sheathing from the cable with a utility knife. Strip 1/2 an inch of the insulation off the end of the white, red and black wires, using wire strippers. Connect the red and black (hot) wires to the brass screws on the receptacle located on each side of the receptacle. Connect the white (neutral) wire to the silver screw located in the middle. Connect the uninsulated copper wire to the green ground screw. Attach the cover to the receptacle.
Turn off the main breaker to the main panel box. Remove the cover and install the 220-volt double-pole breaker to the main bus bar. Remove a round knockout from the side of the panel box. Install a wire connector and push the cable through the connector, then tighten to secure the cable.
Remove the plastic sheathing from the cable back to the connector. Strip 1/2 an inch of the insulation off the white, red and black wires. Connect the white (neutral) wire to the neutral bus bar, located beside the main buss. Connect the uninsulated copper ground wire to the ground bus bar. Connect the red and black (hot) wires to the screws on the 220-volt breaker. Tighten all connections.
Turn on the main breaker in the panel box. Replace the cover to the panel box and turn on the 220-volt double-pole breaker. Test with a voltage meter. Plug the welder into the new 4-prong receptacle.
Tips and warnings
- Check the NEC before beginning, as well as local codes, which may vary from the NEC.
- Cold electrical cable is hard to bend. Store the cable in a warm area, and this will make your job easier.
- Use a rubber-handled screwdriver and wear rubber-insulated gloves when working with electricity to prevent shock.
- Do not work in a live panel box. Always shut the main breaker off before beginning. The wires connected to the main lugs will still be hot after you turn off the main breaker.
- To prevent electric shock injuries and electrical fires, always make sure the screws on the receptacle are tight, especially the ground wire.
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