If you have a 3 wire, then you cannot connect it to a 4 wire outlet. What matters is how many wires are coming to the plug or the outlet. The standard system is a 240/120 or a 120/240/ It doesn’t matter which order those numbers come in. Yet, when you do that, you may be even more confused. Sometimes, you have to go to the horse’s mouth, a qualified electrician, and get them to explain it to you. The numbers they may understand but they do not understand that even when the numbers are the same, the plugs will not work in the same system. The problem is that for most people who are not electricians, the electrical world can be quite confusing. You can find 3 pronged 50 amp power cords, especially on a welder, that will not work in a 4 plug 240 outlet. A three-pronged plug means that there is no neutral wire and it is a true 220 or 240 plug. Everything is now 240 and an RV electrical system is 240/120. There is no 220 in America anymore, at least according to one electrician. Most RVs run off the 120-volt system which means that if you plug your 4 wire 50 amp power cord into a 3 wire system, you may end up frying all your electronics inside your RV. Plug in a 220-volt tool or appliance and check your work.Actually, it can be both. Staple the cable to the wall framing, then turn the power back on.Ģ4. Make the final wire connections to the new 220-volt breaker. Snap a new two-pole, 20-amp, 220-volt circuit breaker into the panel.Ģ2. Connect the wires to the circuit breaker and the grounding bar inside the sub-panel.Ģ1. Feed the MC cable through the connector, then tighten the connector to secure the cable.Ģ0. Slide an anti-short bushing over the metal sheathing on the cable.ġ9. Attach an MC cable connector to the knockout hole.ġ8. Remove the knockout plug from the top of the electrical sub-panel.ġ7. Secure the receptacle to the box with two screws. Gently fold and push the wires into the box. Connect the green wire to the green screw, the black wire to the brass screw, and the white wire to the silver screw.ġ5. Strip the insulation from the ends of the wires inside the box, then make the wire connections to the new 20-amp, 220-volt receptacle.ġ4.

Secure the box by driving two screws through each of its two mounting flanges.ġ3. Push the old-work box into the hole and flat against the wall. Tighten the grounding screw, then reattach the side plate to the box.ġ2. Wrap the green grounding wire from the cable around the green grounding screw inside the old-work box. Remove the side plate from the box, then secure the cable to the box by tightening the cable clamp with a screwdriver.ġ1. Pull the cable through the hole in the wall and into the rear of the old-work box.ġ0. Feed the end of the cable down behind the wall to the box location.ĩ. Use a rotary cutout tool to cut along the box outline, creating a rectangular hole for the old-work box.Ĩ. Drill out two diagonal corners of the box outline with a 1-inch spade bit.ħ.

Hold a metal old-work electrical box against the wall on the mark, then trace around it with a pencil.Ħ. Mark the location of the new 220-volt receptacle onto the wall, making it at least 30 inches above the floor.ĥ. Feed a length of MC 12-2 metal-sheathed electrical cable up through the hole, and then extend it over the ceiling joists.Ĥ. Use a drill and ⅝-inch-diameter spade bit to bore a hole through the top wall plate directly above the sub-panel.ģ. Turn off power to the electrical sub-panel, then remove the cover from the panel.Ģ. In this video, master electrician Allen Gallant provides an outlet for high-powered tools and appliances.ġ.

220 plug in