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I've just moved house and my clothes dryer has a four prong plug but on the wall there's a three prong socket. Do adapters exist for this? Or do I need to get a new cord for my dryer? Or is there another solution?

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This is an electric dryer or a gas dryer? –  The Evil Greebo May 25 '12 at 11:34
    
@TheEvilGreebo Must be electric. Gas dryer wouldn't have 4 prong plug. –  Tester101 May 25 '12 at 11:35
    
Oops, yeah reversed that. Ok - describe the 3 prong plug - does it look like a typical 3 prong plug or is it "unusual" - bigger, with oddly slanted openings? –  The Evil Greebo May 25 '12 at 11:37
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Can you post a picture of the plug and receptacle so we can answer this question without guessing? –  SteveR May 25 '12 at 14:03
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@guy recently had this issue, check the back of your dryer, there might be instructions right on the dryer for switching to a 3 prong cord. –  wax eagle May 25 '12 at 15:06
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3 Answers

up vote 2 down vote accepted

You could replace the cord on the dryer, but you'd have to bond the chassis of the dryer to make that acceptable to current NEC codes (Article 250.140). This can be a safety hazard if done incorrectly, and it may or may not void the warranty on the dryer.

Since your dryer is set up to use a 4 prong receptacle, the optimal solution would be to update the receptacle to a 4 prong (NEMA 14-30R if I remember correctly). However, this will require you to run new cable to the receptacle, since you'll need a cable with a ground. Depending on the draw of the dryer and the length of the run, you'll either have to pull new 10-3 /w ground or 8-3 /w ground cable.

EDIT:

As @TheEvilGreebo pointed out, you may be able to simply swap out the cord on the dryer for a 3 prong version. Check the manufacturers documentation to verify the procedure, and to make sure your model supports this.

EDIT:

This schematic for an electric dryer might help you understand how the dryer could be wired (depending on make/model/manufacture date).

enter image description here

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Actually, Tester, many modern electric dryers are built to be convertible between 3 prong and 4 prong 220. You can buy both styles of cord easily at Home Depot and swap them out with a screw driver and a hex bolt driver - 1/4 or 3/8 as I recall. –  The Evil Greebo May 25 '12 at 12:37
    
@TheEvilGreebo Good to know. I haven't bought an electric dryer since 3 prong was all the rage. I knew electric ranges were this way, but didn't know dryers were too (I guess it makes sense though). –  Tester101 May 25 '12 at 12:40
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As to your edit: To give advice to the OP to wire the dryer in this this way is irresponsible and dangerous! The only correct answer is to replace the receptacle with the correct four prong outlet! –  SteveR May 25 '12 at 14:15
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@SteveR It's only dangerous if the dryer does not have the ability to use a 3 prong cord, if it can use either there is no problem. –  Tester101 May 25 '12 at 14:24
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@SteveR WikiHow is not an authoritative resource, and they fail to site the NEC article they are referencing. I'm giving you the NEC article number 250.140. –  Tester101 May 25 '12 at 16:40
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the easiest thing to do is to replace the outlet, wire a new outlet in, assuming they both use the same type of cable (typically 10-3). you flip the circuit off before you do it, of course. much simpler than looking for an adapter (and probably safer)

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downvoter, explanation? –  amphibient Jun 6 '13 at 18:21
    
Not the down voter; but you took a year old question and made an answer that adds nothing of value not already in an existing answer. –  Dan Neely Jun 7 '13 at 14:37
    
See this suggested edit for some more commentary. –  Niall C. Apr 10 at 16:19
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EDITED for clarification:

The three prong plug has two hot legs for the two bus voltages to add up to 220 volts, plus a neutral wire. Prior to 1998 the neutral was also grounded to the dryer case. A four prong plug has the two bus connections, a ground, and a neutral return. Often these are used if the dryer circuit requires 120 volts at some point, the current would flow from one bus and return through the neutral. If you were to change from a four prong to a three prong and your dryer is designed to use 120 volts at some point, then that current will have to be returned on the ground leg. This is not acceptable by NEC code, nor is it safe. If the 120 Volt circuit were to short, the full 120 volt potential could be present on the dryer case! Imagine touching the dryer at that time, and maybe on a wet floor!

If you can determine that the dryer does not require 120 volts, and that no current is returned on a neutral leg, then I see no reason not to use the three prong (although why does it have a neutral leg at all?). I would ONLY do the conversion if it is recomended by the manufacture. With todays economy I don't think that a manufacture would go to the expense of a four prong plug if it was not required.

The conversion kits mentioned by others may be to convert from a three prong dryer to a four prong receptacle. That is okay, being that the neutral wire is not used.

EDIT:

Wiki tells it like it is. "Modern appliances require 4 conductor cordsets (separate conductors or wires for line 1, line 2, ground and neutral). Generally, this setup is safer, because the current-carrying neutral is not connected to the dryer case. However, it is useless if the wall receptacle does not have a separate ground slot. In that case, you'll have to do the very simple procedure of converting a 4-wire dryer to a 3-wire setup. Conversion of these appliances in the U.S. is prohibited by the NEC (National Electric Code). The receptacle and wiring should be modernized to a 4 conductor arrangement instead."

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The third pin is neutral, not ground. Old dryers use NEMA 10-30 receptacles, which is hot, hot, neutral. They would be wired with 10/3 or 8/3 cable. The chassis of the machine would be bonded to neutral, which basically means the neutral is also a ground, however, the wire would be insulated. –  Tester101 May 25 '12 at 13:45
    
What Tester said. Third pins on 220 plugs are never ground. The options are hot/hot/neutral (3 pin) and hot/hot/neutral/ground (4 pin). –  The Evil Greebo May 25 '12 at 13:48
    
@TheEvilGreebo That is not entirely true. NEMA 6-30 is hot, hot, ground. It's used if 120V is not required. –  Tester101 May 25 '12 at 13:53
    
Did you read the link? "This was a legal grounding method under the National Electrical Code for electric ranges and electric clothes dryers from the 1947 to the 1996" If I am to offer advice it won't be on how it was done wrong in the old days, but how to do it safely today. The practice of using the neutral as ground is no longer used, and that is why he has the correct four prong plug! –  SteveR May 25 '12 at 14:00
    
@SteveR You're right it's not done this way anymore (in new construction), but the third prong was never ground. It was always neutral, it just happened that they bonded the chassis of the dryers to neutral. There was always the potential for current on the third wire; if the dryer used 120V, so it is not a ground. –  Tester101 May 25 '12 at 14:07
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