Dryer 3 versus 4 wires


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Old 12-20-06, 07:21 PM
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Question Dryer 3 versus 4 wires

Hello,

I just moved-out to a new apartment. My dryer has a 4 wires cable, however the plug in the wall only accept a 3-wires one. Should I change the dryer cable to use 3 wires? Isn't less safe? Please advise -)
 
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Old 12-20-06, 08:08 PM
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In absolute terms I guess you could say it is less safe. But it is still allowed to use a three wire cord on a dryer if the building is wired that way.

The important point is, you have to change the dryer set up. If you still have the installation instructions, it will help. Basically, there would be a jumper installed between the neutral (white wire) terminal on the input connection terminal board, and the chassis ground screw.
 
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Old 12-20-06, 08:24 PM
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Since your moving into an apartment your odds of getting a four wire circuit ran for the dryer arent very good. So you are going to have to change the 4-wire cord to a 3-wire cord. We could argue to safety issue till @$## froze over. Suffice to say there are hundreds of thousands of 3-wire dryers out there. Of course it wouldn't hurt to ask for a 4-wire circuit. LOL

If you still have the installation instructions they will tell you how to make the change.

I'll try to summurize what needs to be done.

You will notice on your 4-wire cord the green wire is fastened to the metal frame of the dryer, this is going to change on the three wire connection. The three wire cord will have 2 hots and one neutral but no green ground wire. The neutral is usually white but if you purchase a flat gray 3-wire dryer cord this may not be the case. The neutral on these cords will have multiple ridges on the outer sheath that run the length of the cord but only along the neutral wire. Round black cords will have a white neutral wire inside the black sheath.

If you look at your dryer where the wires connect you may notice there are three terminals, two with brass colored screws with a silver colored screw in between them or the middle screw. This middle screw is where your cords white wire is terminated. Remember it. They may also be labeled by stamping the metal by each terminal. Many dryers have metal straps abput a 1/2" wide connected to the neutral but this strap will be bent over and not attached to the dryer frame. You are going to unfold it and connect it to the dryer frame and leave it connected at the neutral terminal. In other words your going to join or bond the metal frame to the neutral terminal with this strap. If it dioesnt have a strap then look for a wire it should be green or possibly green with yellow stripes. Do not just connect any wire to the neutral you must be sure it is the frame bonding strap or wire. Once you do this the other two wires go to the remaining terminals. Just make note before you disconnect the 4-wire cord. Here is a link to help you through the logic of the 3-wire connection. Copy and paste

http://www.selfhelpandmore.com/switchoutlet/dryer/index.htm

Roger
 
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Old 12-21-06, 12:10 PM
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Thanks for the great explanations!!! I went to HomeDepot and bought a 3-wires replacement cord. I feel confident replacing it. However, I can't find any metal strap or wire that would connect the neutral to the dryer body.

The dryer instruction manual refers to a 'brass strap' which looks on the picture like a cable connecting the neutral screw to the ground screw (where the 4-wire ground wire was previously connected). I went to Sears - where I bought the dryer - to ask for 'brass strap' but they had no idea about what I was referring too...

So, I'm left trying to buy 'something' to ground the dryer to the neutral. I'm thinking a short electric wire sustaining 30 ampere / 120 volt with appropriate ends to connect correctly should do the trick? Is this solution correct? Would anyone have a better one?

I feel weird connecting the dryer body to the neutral (after all the current goes to the neutral). If I connect the dryer body to the neutral and touch the dryer, wouldn't the current flows to the dryer and myself??? (I hope it's not a too stupid question -))...
 
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Old 12-21-06, 12:44 PM
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Not a stupid question at all, in fact it shows you are understanding this conversion very well.

Yes it does seem odd but it is as safe as your going to get under the circumstances. There is little chance that you will be harmed in any way. This is a very common connection across the country. The low impedance path with this connection is much less than a path through the human body so any current will travel the neutral wire under normal conditions. If a fault occurs to the frame of the dryer the bonding strap allows the fault current to travel the neutral wire back to the main panel and trip the breaker.

If the strap is missing make one out of 10 awg green insulated thhn wire and connect as the instructions show.

Roger
 
 

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