Here is what you want to use:
http://www.quick220.com/220_volt.htm
It allows you to use two 120 volt circuits to develop 240 volts. Be sure the amperage and wattage parameters are what you need.
Here is what you want to use:
http://www.quick220.com/220_volt.htm
It allows you to use two 120 volt circuits to develop 240 volts. Be sure the amperage and wattage parameters are what you need.
Howie.........
Well fancy that ... someone thunked of the safety problems and made a product for it.
To make sure this isn't misinterpreted - this nifty little device will ONLY ONLY ONLY work if you have more than one 120v circuit feeding your space. It will NOT work if both outlets are on the same circuit. Read the FAQ before plunking down $150 bucks!!!!
Jason Beam
Sacramento, CA
beamerweb.com
Based on that little do-hickey, it would not be hard to make something similar and better.
What if you took a small subpanel, fed it from two 120V circuits (giving two hots, a neutral, and a ground), installed a 220V circuit breaker (giving you the trip-one-hot trip-both-hots requirement), and attached a suitable 220V recepticle. Thoughts? I think it would run you a lot less that the Quick 220 at $150.
Not quite - the thing missing is a sensing mechanism to completely cut off power if either of the 120v plugs are pulled out. That gizmo claims to do this. You'd need some kind of relay setup or sensing circuit to accomplish the same.
Jason Beam
Sacramento, CA
beamerweb.com
True. True. I missed that. But two high amperage contact 120V coil relays would do the trick. With the right subpanel, it could all fit in there. But now I think you'd be close to the price of the pre-made gizmo. I didn't see in their literature about overloading and which breaker(s) trip or if the 'box' has it's own breaker. But then again, based on the design, if only one breaker trips, then the light goes out and power to the equipment is lost. So I guess that's good too.
Last edited by Anthony Whitesell; 03-04-2009 at 3:47 PM.
I'd think that you'd need a relay/contactor with a 240v coil where both hot legs flow through the relay/contactor. Using a 240v coil means that if either 120v leg drops out the relay/contactor will open.
I'd have to think about it for a minute in terms of how I'd wire it with (2) 120v coil relays, but it would certainly complicate things.
No theory here .. it CAN be done, and done SAFELY, although, probably not in your situation.
I had a friend who wired all of his duplex recepts. in his shop in such a way that the upper outlet was on one breaker, and the lower outlet on another, fed from the other leg of the box. He made up several pigtails that had two 120V plugs and a single 240 recept. n His thought was that he could provide 240V anywhere in his shop with that setup without hard wiring any 240V recepts.
He asked the inspector first, and although he didn't like the idea, he said it was not a code violation. As was stated earlier, the inspection only dictates what goes on behind the wall covering, NOT what you plug into it.
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Chris: Yet you thought it was a bad idea in your first reply?
Same setup as propositioned by OP, and just as dangerous.
Good point about breaker access however, I'm pretty sure the code *does* say something about the only disconnects being located in an inaccessible location.
WRONG.
It can NOT be done safely that way. FLAT OUT PERIOD NO. NO NO.
I ask you - pull one of those plugs and put a meter on it and tell me it's safe.
No disrespect, but that is very dangerous advice.
Unless something is placed on that cord to prevent the MALE ends of either 120v plug from being live, IT IS FLAT OUT NOT SAFE
I ask anyone reading this thread now to be very sure you understand why this is not safe if you're going to attempt this technique.
Jason Beam
Sacramento, CA
beamerweb.com
Wow... first off, thanks for all of the great information, I didn't even know if I'd get a single response... alot of "hot" ideas here
This is more or less along the lines of what I was originally thinking... and I knew I was missing something... now that I know the safety concerns of backfeeding one tripped 110v circuit into the other, I realize that wont work.... unless.... I just thought about this... what if I install a capacitor on each of the hots on the 110v leads... shouldn't that stop the flow of power to the untripped circuits? Then there is no need for a relay or comlicated wiring... of course I have no idea how much a 110v 15amp capacitor would cost.
Jason, check me on this, please. I'm trying to be sure I understand why it's dangerous.
You've got two power cords going to the load, each plugged into separate 120v sockets. One power cord gets unplugged while the other is still plugged into a live circuit. Is that the scenario we're looking at?
If so, that's the same situation as a single power cord with a plug on each end where one end is plugged in and the other just laying out on the floor. In that case, the "hot" prong of the unplugged end is directly connected to the live "hot" and exposed for all the world to see and touch. Really no different than sticking a knife into the hot side of any live receptacle.
Am I understanding it correctly?
Tom Veatch
Wichita, KS
USA
If it were DC, the capacitor would stop the flow once it were charged up, but a capacitor will pass AC current. The smaller the capacitance, the higher the effective resistance at a given cycles per second but you'll still get some current flow for any finite value of capacitance.
Tom Veatch
Wichita, KS
USA