clothes dryer got me stumped

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Old 11-25-11, 09:35 AM
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clothes dryer got me stumped

I tried three different clothes dryers, one brand new, and got the same results: dryer turns but doesn't heat up. On all three dryers, I tried different settings. I also tried different breakers. I tested the heating elements with an ohmmeter on one of the used dryers and it was fine. But then I wired directly to the element (a hot on each lead; grounded to the frame) and it didn't heat up! So I cut the plug off an old toaster, grounded it, and tested the hot lead against each hot lead from the breaker. The toaster heated off both leads. What the heck is going on here?!
 
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Old 11-25-11, 10:24 AM
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What is the voltage across the two hot wires at the dryer receptacle? An electric dryer's motor runs off 120 volts, as do the controls, but the heating element needs 240 volts.
 
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Old 11-25-11, 10:42 AM
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It is unlikely that two different dryers would have the same exact problem!
(Let alone 3.)

I would start looking at the cord, electric outlet, wiring to the electric outlet, and circuit breaker.

Voltage can be tested with a multimeter. Search google.com for the words...
How to use a multimeter
 
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Old 11-25-11, 10:55 AM
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So I cut the plug off an old toaster, grounded it, and tested the hot lead against each hot lead from the breaker.
If for instance this is a GE breaker box it could mean the 240 breaker is in the wrong position and both dryer hot legs are on the same supply leg. With other brands of breaker boxes it could mean they used a single pole tandem instead of a two pole breaker or it could mean they used two single pole breakers and put both on the same supply leg.

As stated you need to measure the voltage across the two hot legs of the receptacle. Use a multimeter or if your intent on jerrry rigging a tester connect to lamp holders in series and use the same watt bulb in each. Bulbs half bright is 120v, full bright is 240v.
 
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Old 11-26-11, 03:23 AM
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voltage

I'll check the voltage across the leads when I get around to messing with it again, probably after work today, then get back to you. You mean touching a VM test probe to each of the wires across the breaker at the same time, right? I don't hold out a lot of hope, though, because I wired a stove, water heater, and the old dryer out of the same box, and tried two different breakers for this job.

Thanks for the input.
 
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Old 11-26-11, 06:19 AM
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That would be the correct test. You should read 240 between the screws of the breaker.
 
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Old 11-26-11, 07:22 AM
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You mean touching a VM test probe to each of the wires across the breaker at the same time, right?
You should do the same right at the receptacle.
 
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Old 11-26-11, 03:01 PM
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confused

I ran the VM probes between neutral and ground on the back of the dryer, with power going to it. I got 120V between the ground and each hot, but when I put the probes on both hots, I got nothing.
 
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Old 11-26-11, 03:23 PM
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They are either on the same side of the 240V buss...or you have a broken wire.
 
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Old 11-26-11, 03:42 PM
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Originally Posted by Gunguy45 View Post
They are either on the same side of the 240V buss...or you have a broken wire.
I agree. Did this just stop working?
 
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Old 11-26-11, 04:16 PM
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Originally Posted by 135steward View Post
I ran the VM probes between neutral and ground on the back of the dryer, with power going to it. I got 120V between the ground and each hot, but when I put the probes on both hots, I got nothing.
More likely you have both hots on the same supply leg rather then a broken wire. A broken wire would have most likely showed one leg dead. This is what I suggested in my original post:
If for instance this is a GE breaker box it could mean the 240 breaker is in the wrong position and both dryer hot legs are on the same supply leg. With other brands of breaker boxes it could mean they used a single pole tandem instead of a two pole breaker or it could mean they used two single pole breakers and put both on the same supply leg.
 
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Old 11-26-11, 04:18 PM
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Oh duhhh...yes..if you have 120 to ground on each side..then not a broken wire.
 
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Old 11-26-11, 05:04 PM
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I'll mention something that "everybody knows" who does electrical work. Some things are so common, we forget that other people may not know about these things!

Anyway the following is a diagram of a circuit breaker panel without any breakers. Ignore the little comments on the diagram.

At the top of the panel would be connected two large wires. These are both "hots" coming from the electric company. Measuring between these you would get 240 volts.

And at the top right there would be another large wire connected. This would be the "neutral" coming from the electric company. Measuring from the neutral to the hot on the right would get you 120 volts. Measuring from the neutral to the hot on the left would get you 120 volts.

Now notice the connections, where the breakers go, alternate... Left hot, right hot, left hot, right hot, etc.

So if you place a "tie bar" double breaker in the panel, then one breaker output would be from the left hot at the top and the other would be from the right hot at the top. And measuring from both of these breaker output hots would get you 240 volts.

If a 240 volt circuit was connected to one breaker, then skipped a space and then connected to another breaker, then they would both be on the same "leg" or "phase" or "hot wire above". Measuring between the two outputs would give you 0 volts.

Or if someone used just two wires for the panel (1 hot and 1 neutral), then connected the hot to both of the top connections, then you would get 0 volts between them as well.

 
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Old 11-26-11, 09:30 PM
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Originally Posted by 135steward View Post
I ran the VM probes between neutral and ground on the back of the dryer, with power going to it. I got 120V between the ground and each hot, but when I put the probes on both hots, I got nothing.
And.....did you do the same test at the breaker?
 
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Old 12-01-11, 06:30 AM
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dryer wiring

I looked at bill190's info. This is my first day off since the posting. Anyway, I'm using a 3-wire cable, both hots to a breaker on the same side of the box, and a grounded third wire. I get 120V between each hot and ground, but 0V between the hots. So bill190 described my wiring. Is this why the dryer doesn't heat up? Where do I go from here?
 
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Old 12-01-11, 06:48 AM
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Possibly if you could give the brand and model of the panel and the rating and positions of the breakers. There are 2 breakers aren't there?...you said "both hots to a breaker on the same side of the box".

A picture might also help...you need to upload to a hosting site then link back in your post. Instructions are here.....Electrical & Electronics | DoItYourself.com
 
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Old 12-01-11, 07:23 AM
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thank you bill190

You nailed it. I didn't split the poles on the breaker. The dryer works great now. But now my wife's going to make me wire the other used dryer, too. Every silver lining has its cloud, huh? Bill190, you're my hero. Thanks again.
 
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Old 12-01-11, 09:12 AM
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Actually I gave you the answer in my first reply. You just ignored it. There is still a serious issue here. Are you using two single pole breakers instead of a double pole breaker?
 
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Old 12-01-11, 09:37 AM
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Wait... Hold the phone!!!

So both hot wires were going to one breaker?

Note you need to use a "double" "tie bar" breaker with the correct amperage (number on the handle(s) of breaker) for the size of wire you are using. Was this done?

A 240 volt double tie-bar breaker...

 
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Old 12-01-11, 09:42 AM
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And to the statement about wiring the other dryer.....it can't be done the same as your existing wiring, I don't believe. It needs to be a 4 wire circuit (isn't that right Pro's?).
 
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Old 12-01-11, 10:49 AM
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You guys are right

I did overlook your reply, ray. Thank you. And now that I know what I did wrong, I know I have to replace the breaker. And I talked my wife out of the other dryer. I told her it would place too much draw on the breaker box.
 
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Old 12-01-11, 11:14 AM
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Do you know what size wire you are using for the dryer?

And if it is aluminum or copper?

Note if using aluminum wire, you need to brush on anti-oxidation compound to the bare wire part before connecting to an outlet or breaker.

Also a dryer installation or instruction manual will say what size circuit is recommended for that specific dryer. Same with other appliances like an electric range.

These instruction manuals are usually on the dryer manufacturer's web site. Or you could call them and ask.

If the wire to the dryer is exposed, you may be able to see the wire size printed on the jacket.

WARNING: If the wire is too small and the breaker amperage too big, you will burn your house down!
 
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Old 12-02-11, 08:55 AM
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Normal dryer wiring in the US is 10 gauge copper with a 30 amp double pole breaker.

New installations require a 4 wire wiring method.
 
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Old 12-02-11, 02:39 PM
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wiring

I'm now using a 30-amp double-pole breaker. The wire is 10-gauge copper, but only 3-wire. I don't have inspectors to answer to. Thanks again for your help.
 
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Old 12-02-11, 02:52 PM
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Regardless of whether there are inspections or permits the work should still be installed correctly and safely.
 
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Old 12-02-11, 05:35 PM
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Originally Posted by 135steward View Post
I don't have inspectors to answer to.
You have this forum and that can be worse than an inspector!
 
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