220v connection to dryer


Old 10-21-05, 09:35 PM
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220v connection to dryer

Anyone know if I can switch out a 3 prong 30A dryer plug for a 4 prong 30 amp?

My dryer connection is using a 4 wire connection. I purchased a new plug and it has white, green, red or black, red or black connections. The old plug has white, black, and green. My guess is that the white and black were both hot and the green was for the ground.

Sound right?
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Old 10-22-05, 05:17 AM
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If there are only three wires in the existing receptacle, you can't switch the receptacle to a 4-wire without changing the wire back to the circuit breaker box.
If you don't change the wire to the breaker box, then you need to convert the dryer to a three wire cord/plug. Conversions are available at the appliance store.
Old 10-22-05, 05:36 AM
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If the feed coming into the drier is three wire it's 240V with ground.
If the new drier has four wires it may need 120V as well as 240V to operate. In that case you will have to change the feed to four wire red, black, white and plus ground.
If the drier only needs 240V you could connect all the wires to the new plug and replace the male wall plug with a matching 4 prong receptial just leave out the 120V slot empty. But the question is, can you do it?
The new code calls for four wires for a drier so I don't know if this set up would be to code. Possibly one of the moderators could jump in and clarify this.
While I was writing this Ron posted. I'm not sure I would change any wiring in the drier unless there were specific instruction in the user manual for doing this. Manufactures will use any excuse to void a warranty.

Last edited by ollie; 10-22-05 at 06:26 AM.
Old 10-22-05, 07:01 AM
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Do you want to change the receptacle in the wall, or the cord and cord-cap on the dryer? It is not clear from your post just what you wish to accomplish.

Old 10-22-05, 07:17 AM
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All new US electric dryers come with four wire cord and plugs. They also come with instructions on how to convert the dryer to a three wire cord and plug. It is not as simple as just replacing the cord and plug, there is one other step. Three wire cord and plugs are available at all the home stores, and probably from the appliance store as well.

If you have a three wire receptacle on the wall then you have two options. 1) Replace the receptacle with a four wire receptacle, which usually involves running new wire to the breaker panel; or 2) Replace the cord and plug on the dryer.

It is better to replace the receptacle, but this may not be easy or practical, which is why you are allowed to replace the cord and plug.
Old 10-22-05, 07:58 AM
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Sorry, I was having a hard time explaining it.

I have a 3 wire welder cable which I want to hookup to my 4 wire receptacle without having to switch out the receptacle.

I bought a new 4 prong plug that fits the current receptacle The old welding cable is a 3 prong/3wire.

The new plug diagram is X and Y (left & right) and W and G(top & bottom). From the extention cord, I was going to put Black & White on X and Y since those are both of the hot leads giving me 220v.

I'm not sure if I hook up the green one to common or ground? I know the fourth wire is for a seperate ground and would normally use the green wire, but in this case there would be no common. The extention cord has a black, white, and green wire. I was thinking of using the green as the common, and leave the ground disconnected.
X (black) Y (white)
............ W(green)

This is just a temporary solution for now. I just need to see if the welder works.

Here is the type of receptacle I have:

Last edited by bigblock; 10-22-05 at 02:20 PM.
Old 10-22-05, 09:05 PM
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First thing you need to determine if the dryer circuit is suitable for your welder in terms of wire size and breaker setting.

Next, you mention that the welder uses two hots and a common. It is almost certainly the case that this welder uses two hots and a _ground_, and does not use the common (neutral). Some welders use 120V, many use 240V, but it would be a rare beastie indeed to use both 120 and 240 at the same time.

If this is the case, then you want to connect the welder to X, Y and G.

Old 10-23-05, 08:39 AM
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Thanks for the info. The dryer is a 220v 30 amp and that's the same the welder needs as well. I just don't want to hook it wrong and fry the welder or burn down the house...
Old 12-12-05, 08:34 AM
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Originally Posted by bigblock
This is just a temporary solution for now. I just need to see if the welder works.
Not sure how comfortable you are with electrical work, but here is what I would do to test a welder with your setup.

NOTE: Only do this is you know how to safely work with electricity

Go to your local hardware store and get a few feet of 10-3 wire and the receptacle you need.

Open up the box that contains your 30 amp circuit breaker. If you are learning something by me saying "turn-off the breaker" stop now and forget my advice about this. Remove the wires from the breaker. Hook up your new short wire and receptacle to the old braker. Test your welder right there near the breaker box.

Once you know it works then you can do any and all future wiring mods you might need. You need a new receptale anyway, and wire is less than $2 per ft.

BTW are you planning to weld from your 30 map dryer plug? Do you need to keep the old dryer plug ready to use? Make sure your welder isn't 50 amp.
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