Need Help With 240 Circuit

Elast

Hey guys, sorry for my ignorance but I am just a mechanic not an electrician. I had a short in my fuse panel on dryer circuit (upstairs) at home, old house had only #12 wire on circuit ,so I disconnected the wires from the fuse panel and installed a new #10 wire circuit from breaker panel downstairs to dryer receptacle. I wired as follows:
2-30 Amp breakers(stabloc type)
White neutral to neutral bar in box
Green to groung bar in box
Black to breaker
Red to breaker

Tested receptacle with 120 volt light , white and black wires, light will illuminate
white and red wires, light will illuminate: therfore I have 2-120V circuits at receptacle: therefore 240V circuit, Correct?

Now for problem, short fried my dryer. Bought new dryer from Home Depot, plugged in, no power at all. Took off lid off new dryer for quick look and discovered that the White neutral wire from dryer cord inside dryer was cut off and shrink tubed(factory) not hooked up to anything

Question: how can dryer work on 240V (or 120V) circuit with white neutral wire not hooked up? Does not the neutral have to be hooked up in order to get AC current flow? Only red and black wires are hooked up to power circuit and green wire is grounded to dryer case. It would seem to me that the issue is not my house wiring but lack of neutral wire hookup in dryer.

Can anyone shed light on this issue for me.

Thanks to all for any help you can give me. Elast

thom

There are a couple of issues here.

You should have a single 2 pole breaker, not 2 single pole breakers. The way you tested, it's possible you have 2 circuits at 110V that are off the same hot bar in the panel. This would provide 2 circuits at 110V to ground/common but no voltage differential between the two hots. Get the correct breaker installed, then get a volt meter and measure the voltage across the two hots in the receptacle. After that insure that you have both common and ground continuity. Test between a hot and common (shows 110V) and a hot and ground (shows 110V).

220V equipment does not necessarily require a neutral in order to operate properly. Oftentimes controls are run of one hot and a neutral (110V) but the controls could just as easily be built to operate off two hots (220V). In any event, the controls will be run through a step down transformer prior to powering the control circuits.

We are required to install receptacles that provide a common, a ground, and two hots. This does not mean the manufacturer must utilize them all.

Elast

thom, thank you for the quick reply. I realize now my mistake and will install a dual breaker instead of the 2 singles. I thought I was doing the same thing using singles instead of a 2 pole but as you noted I was incorrect. I will post my results later after I install the dual breaker.

Elast

mdshunk

If you use two "thin" single poles, or one "thin" style double pole Stab-lock breaker, it is possible to plug it in so they're both on the same phase. You need to straddle two buss stabs to get 240 volts with the thin style FPE's

HVAC_NW

Many dryers run the heater element (the big power) on 240v, then power everything else from one of the poles + neutral on 120v. Some doesn't use neutral at all and run everything on 240v. It's completely up to the appliance manufacturer to do what they want.

Check voltage from neutral to hot A and hot B. should be 120v each. Check across hot A and hot B. Should be 240, if you get zero, you have both of them connected to the same pole.

If you get two singles and make sure they're on separate buses, your dryer will work, but it's a SERIOUS safety hazard and there's no way NEC would allow it. You MUST use a common trip breaker. Using two singles, if one of the poles shorts to the ground, that one will trip, but the dryer will be still energized by the other one. I'm surprised nobody pointed this out.

This is why it's a good idea to hire an electrician to do it. Just because it runs/lights up doesn't mean it's safe.

Elast

Thanks everyone. I removed the singles installed a double. Stupid me I had it on the single phase. I moved up one spot to straddle and voila 240V. Everything fine now. The old addage that you learn something new everyday holds true. Again thanks for all the help. You guys rock.

Elast

Celtic

It's still single phase......
Just 240V 1Ø

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