I believe I saw an article somewhere showing how to split off 220v to 110v. I’ve made a 220v “outlet box” with three 220v outlets (only one will be used at any time). I would like to add a 4 outlet box for 110v to it by splitting off of the 220 line so I won’t need two cords going across the floor. I currently have a three wire 12 ga. cord. Is this doable or a bad idea?
mousejockey
Replies
Part of the question that you didn't ask has to do with the overall load in amperes. Are your wire and breaakers sized to the load you intend to put on them?
If so, is your current 240 box simply a receptical box, or is it a load center? How is it grounded?
Bottom line: there are ways to take 120 off of 240, but some may be dangerous or in violation of code (because dangerous).
Joe
Passing on the merits, or not, of doing this for now, you will need a cord going into the box that has four wires, a ground (green), a neutral (white), and two hot wires (red and black). The 220 volt outlet in the box will need to have four slots, one for each of the incoming wires. If you don't have the four wire cord and the four slot outlet you won't be able to a plug into the box with an adapter to create a 110 volt plug box.
220 volts is created by going from one of the hots to the other, the neutral wire isn't needed. To get 110 volts you need to go from one of the hots to the neutral. If your 220 volt cord doesn't have the neutral wire you can't create a 110 volt circuit.
John White, Shop Manager, Fine Woodworking Magazine
Thanks for the info. That's the reason I was asking the question, I only have three wires to the 220v outlets, two hots and a gnd. I couldn't figure out how to get a neutral. Looks like a seperate cord if I want a centralized outlet box for 110v.
This is attached to the back of my tablesaw, more or less the center of my garage so it's more convient to connect to power.
Thanks again.
Over the Hill? What Hill? I didn't see any Hill!
I'm not 100% certain, but I'm pretty sure that you need to use 4-wire for all new 220v outlets. (Although 3-wire is OK for existing outlets.) I know this is the case for, e.g., dryer circuits.
Mike HennessyPittsburgh, PA
Of course, what John White is talking about is really a splitter cord and not a new outlet. I agree with John that balance is not too important, and won't be different with the splitter than it would coming off a panel.
What I really wonder, though is if OP is right about having two hots and a neutral. Isn't it more likely to be two hots and a ground? In 240, the two hots act as neutrals to each other due to the characteristics of AC, and the difference in phases. If it is a true neutral, he'll need a true ground as well, won't he? If it is a ground, and does not just run back to the panel without being re-grounded en-route, he may have very different problems.
He needs to know.
Joe
Joe,
A couple of messages back he says he has two hots and a ground, so he has what he needs for a safe 220 volt circuit provided everything is hooked up properly.
John W.
Hmmm. Good point. I guess I need a remedial reading course. Oh well.
J
Essentially the service to your house is 220-Vac. There are: a common (white); two hots (black and red or black and black); and ground (green).
The voltage between the two hots is 220, the voltage between the common and either hot is 110. So, hooking up either hot lead and the common will give you 110.
What you are describing is a sub panel on a flexible feed line. I don't think I would do it as it is going to be hard to keep the load balanced.
The imbalance for the system as a whole wouldn't be any worse than if the 110 volt circuit came directly off the panel, and an imbalanced load doesn't create any special problems with the cord, or am I missing something?
Household loads are rarely balanced with any great precision and are highly variable, so the balance is rarely worried about.
John W.
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