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I just moved into a home and I am hooking up a used dryer (which I'm told works). The dryer spins, but I get no heat.

I bought a multimeter, and it tells me that the receptacle provides insufficient voltage for both the dryer's spin and heat. The receptacle is a NEMA 10-30. Referring to the poles as listed in this diagram, I get the full 120V between poles W and Y, but only 45V between poles W and X (and 70V between X and Y). I think, from these DIY questions (1 2), that I should get 120V between W and X and 240V between X and Y.

NEMA 10-30

I even took the receptacle off the wall, and I get the same readings from the bare wires.

So here's my question: is it time to call an electrician, or are there some other things I can investigate on my own?

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I'm stumped trying to figure out where the 45V is coming from. It's in phase with Y, so that's why you're losing voltage when you connect X and Y. If you're comfortable opening up the breaker panel, then you can check the wiring coming out of the breaker. Otherwise, unless someone else chimes in, I'd call in the electrician, and then be sure to let us know the solution. –  BMitch Jun 1 '11 at 11:16
Be sure you have set your multimeter to measure AC (alternating) volts, not DC (direct current) volts. –  Bryce Aug 14 '12 at 23:01

1 Answer 1

up vote 11 down vote accepted

a broken wire or loose connection can pass voltage but as the current draw goes up, the voltage goes down. depending on the quality of the break, the voltage at no current draw (such as with a multimeter) could vary from full voltage to almost nothing.

to really figure this out, you'll need to remove the cover of your breaker box. measure the voltage between the neutral bar on the side of the box and the incoming wires from the meter at the top. they should all read 120V or 0V. if not, then the power company needs to investigate.

also measure between the neutral bar and the two screws on the side of the breaker that feeds the dryer outlet. those should read 120V. if not, then the breaker is likely bad.

otherwise, the problem is likely a broken wire or loose connection somewhere between the breaker and the outlet.

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Great answer, longneck. I opened the breaker panel and tested the voltages. Sure enough, I got 120V from one terminal of the (double-pole) breaker to the ground strip, but only 45V from the other terminal. And I got 120V from the source of the breaker to the ground, so the problem was indeed the breaker. Thanks a lot! I'll be replacing the breaker soon. –  Jeff Terrell Ph.D. Jun 3 '11 at 18:48

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