HOW TO - make a 220V extension cord

[fredf]

Tony

If you only need 220v (2 hots + ground) you can use 3 wire SO cord, It would be a good idea to mark the white wire with paint, tape or shrink tubing, although it is often not done. As always Green is Ground the World around . . . NEVER use the green wire to carry current. if you need 110 /220 use 4 wire and use the white for a neutral. If you used the green and the wire failed, you would end up with 110 on the case of your tool(s)!!!!! It could ruin you whole day.

I don't have the particulars in front of me, but it is possible to used undersized conductors for welders and other equipment that doesn't operate continuously at full load (duty cycle) if you go with the continuous ratings, however you cant go wrong

[thenrie]

Yeah. I could have used 10-3, but I already had the hardware and it was all 4-wire. Since I wanted to split off a 110v outlet, I figured I'd go ahead with 4-wire, so I would have a common AND a ground. I figured a little extra safety on a extension cord wouldn't hurt.

I think your point about the white as common is important for folks to know, as long as they understand that on a 3-wire cable for 220v the white IS HOT, but on a 4-wire cable it is the common. The green is ground ALWAYS. Recoloring the HOT WHITE is always a good idea. Make it black or red.

Your last point is also a good one, and a cost saver. You can run a dedicated circuit for particular tools/appliances using smaller than normal cabling, but it has to be a dedicated circuit to pass code. I don't know what the particulars are either, right off-hand. My dedicated welder circuit is #6 THHN on a 60 Amp breaker right now, but I may move up to a 100 amp breaker to allow me to use the full potential of my Maxtron 300. My welder's manual indicates that is appropriate sized cable for my welder. Otherwise I'd be running 1/0 copper cable. Very expensive! I'll still have to check with the county to make sure my set up meets code, though.

Be safe. Do things right.