Q: I have a 4-prong 220v outlet in my shop. I don't need 220, but I do need another 110 circuit. My junction box is full, and I don't think it's a good idea to add more outlets to the existing 110v outlet circuit. Even if it would be safe, I prefer not to. As any electrician knows, three different pairs of prongs on the 220v outlet have 110v across them. Would it be a problem for me to create an extention cord by wiring 2 lines of a 220v plug for that outlet (plus ground, of course) - but with 14/3 or 16/3 wire and ran to a standard 110v outlet? I could also remove the outlet, cap off one of the lines, and replace it with a 110v outlet. I don't know if that's safe, however, or up to code (since it's a change to the house wiring, not just an extention cord). I don't see any problem with the first option (extention cord), and there might not even be a problem with the second option. But I'm not a licensed electrician, so I'm not sure. Any help or ideas appreciated!
A: Don, You can do what you say but some specific items must be observed. I will assume that this is residential and you have a single phase circuit here. Your wires are hot 1 (usually black) hot 2 (usually red) neutral (white) and ground (green or bare). Verify this. If you have commercial three phase you will have three hots (usually all black) and one neutral (white) You will need to replace the two (resid) or three (comm) pole breaker with a single pole breaker and a blank (or another single pole and don't use it) Wire nut off each end of any wire you do not use. The breaker will need to be 15 or 20 amps. Be sure you get a 20 amp plug if you want a breaker that large. 15 amp plugs are the standard ones you but at the store. Use the black for your hot leg, the white for your neutral, and the green or bare for your ground. Even though the neutral and ground may be on a commonly bonded strip in your panel you must run them separately all the way back to their proper strip. If your wire size is 12 gauge you can use 20 amp breaker. If it is 14 guage you may only use a 15 amp breaker. If the old breaker is a 30 or larger you can still use the large wire but you must decrease the breaker size. Your municipality most likely requires you to pull an electrical permit for much more than like kind replacement. Most states allow for a "homeowner" permit. You will be subject to the same code laws and inspection as an electrician and you may not do work for another person. Otherwise you must be a licensed electrician. 16/3 is good for a 12 amp load. Much more than a vacuum cleaner and it will overheat. Buy a heavier extension cord. So, after all these words, you can do either option. Remember if something doesn't seem right it most likely isn't and you need to consult an electrician. Its really not that expensive of an investment. I have heard of do-it-yourself jobs that started a fire and the insurance refused to pay and filed arson charges against the homeowner! Good luck Craig