I think my 4 prong dryer outlet is wired incorrectly

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  #1  
Old 09-13-11, 04:21 PM
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I think my 4 prong dryer outlet is wired incorrectly

Hey guys, I have searched all over the internet about this but nothing has addressed my specific situation. I moved to an apartment with a 4 prong dryer outlet but my dryer had the older 3 prong cord. No problem, I switched out the cords and tried starting the dryer with no luck. I took the plug out of the wall and noticed that it has no neutral wire attached, only 2 hots and a ground. I have had maintenance in here twice but they tell me there's no problem because the plug is putting out 240v. Can someone please confirm that the lack of a neutral wire in a 4 prong outlet is both the reason why my dryer won't run and also a code violation? I have a picture of the outlet but I'm not sure how to upload. Thanks in advance for any help you guys can provide.
 
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Old 09-13-11, 04:44 PM
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We will need more information on the dryer. The pros can say for sure but the 3 prong outlet would meet code depending on when it was built/installed. Older dryers used the 3 prong outlet and the newer ones use 4 prong as your does. What you have on yours are two hots, a ground and a neutral. You should be able to connect each of the hots from the dryer to one of the hots on the plug and connect both the neutral and ground to the ground/neutral on the 3 wire plug.
 
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Old 09-13-11, 04:56 PM
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I figured I could probably combine the neutral and the ground from the dryer to ground that is attached to the outlet but I wasnt sure if that's safe. It seems a little counter productive for them to have installed a 4 prong outlet and wired it like a 3 prong. I just assumed that since they have a 4 prong outlet in the wall it should have all 4 wires supplied to it (2 hots, a neutral, and a ground). I have the cord wired to the dryer as follows: the two hots are attached to the outside terminals, the neutral to the middle and the ground to the dryer chassis. When I test it with a voltmeter I get 240 across both hots, 0 between hot & neutral, and 120 between hot and ground if that helps any.
 
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Old 09-13-11, 05:25 PM
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As you suspected, it looks like someone took a 3-wire dryer and popped in a 4-prong receptacle. Older dryer installations did have simply the Hot/Hot/Ground configuration, which is certainly less safe than the 4-wire configuration, but is still used quite a bit and is not unsafe.

If it were my house, I'd install a 3-prong receptacle and a 3-wire cordset and call it done. Using a 4-prong receptacle on a 3-wire circuit is counterintuitive, but I'm not certain it's really a code violation. Plus, I know I get tired talking to a brick wall after a while.

You can use your 4-wire cordset as if it were a 3-wire. Bond the neutral and ground at the dryer and tape up the 4th unused (neutral) wire. When you leave, I'd also leave a note saying that the receptacle is wired wrong.

Or you can keep trying to convince the maintenance staff that they are wrong... that the 4-prong receptacle should be giving 240/120... *shrugs* Good luck.
 
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Old 09-13-11, 05:29 PM
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I took the plug out of the wall and noticed that it has no neutral wire attached, only 2 hots and a ground.
If there is no white wire this is a 240v only circuit and can't be used for the usual 120/240v dryer. You can not use a bare ground or green wire for neutral.
 
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Old 09-13-11, 06:09 PM
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IIRC if the cable is SE you could use the bare as the neutral/ground. If it is NM you cannot use the bare as the neutral/ground.
 
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Old 09-13-11, 08:26 PM
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Originally Posted by pcboss View Post
IIRC if the cable is SE you could use the bare as the neutral/ground. If it is NM you cannot use the bare as the neutral/ground.
Although there was a time when NM was sometimes used like this with the bare ground wire being used as a neutral. It was never right, but some hacks just don't know the difference and/or don't care. Just because it works doesn't mean it's right or safe.
 
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Old 09-14-11, 09:14 AM
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Originally Posted by walkeru View Post
I have had maintenance in here twice but they tell me there's no problem because the plug is putting out 240v. Can someone please confirm that the lack of a neutral wire in a 4 prong outlet is both the reason why my dryer won't run and also a code violation?
The maintenance man is wrong and the receptacle is wrong. It should be a NEMA 10-30R with the bare wire on the middle ground/neutral pin. The dryer should have a 10-30P plug to match with the chassis ground and neutral terminal bonded inside the dryer wiring compartment.
 
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