3-wire dryer outlet with ground??

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Hokie_Brewer

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Looked at my dryer power outlet today and saw something fishy. It's a 3 plug dryer outlet, but it seems to have a ground wire coming out of the wall and connected to the junction box?

Anyone know of a reason you would have a ground wire but still wire a 3-wire plug?ImageUploadedByHome Brew1393369708.742305.jpg


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brew_ny

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is it coming from a main panel ? they more then likely put the ground to the metal box because it is a metal box

they used a wire that was 3 conductor with a ground so the wire was there anyways

if it is from a main panel the neutral and ground bar are bonded so they are about one in the same

but I am no sparky so take it with grain of salt, how old is your wiring? what was code then?

saw something fishy
maybe not

all the best

S_M
 

gtmaus

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its a mechanical ground. On a 3 wire dryer cord you just ground the box. It's all good.
 
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Hokie_Brewer

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Panel was last inspected in 1986. Don't know if it runs to the panel or not. Any ideas?


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HappiBrew

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It's a standard 240v plug. It's not the same as the 120v plugs in your typical wall outlet but fairly common in electric dryers.
 

teckmaster0179

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On a 240v system, you have 2 positive wires and a neutral. You still have a bare copper wire to provide grounding. On a dryer, you basically have 2 110v units. 1 spins the drum and the other heats it up.


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ingchr1

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From my understanding the 3 prong is normal for older installations. The ground wire is there to ground the metal box. Current code would require a 4 prong, for new installations. Ground would go to the receptacle and metal box.

If you do change it over to a 4 prong, you should remove the jumper in your dryer connecting neutral to ground. The new cord on your dryer would then have the ground wire to ground (chassis of the dryer) and neutral to neutral. Ground and neutral separate at the dryer. If you have it, the install manual for your dryer should detail this.

Of course this all depends on the age of your dryer. But I I think it's been this way since at least the 90s, from what I've read.
 
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Hokie_Brewer

Hokie_Brewer

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So my understanding was that most old 3-wire dryer outlets don't have a ground running to the panel at all? Therefore to rewire the outlet to a 4-wire plug would require running a new ground line to the panel.

I guess my question is, do you think this ground leads back to the panel and therefore changing it to a 4-wire outlet would be very easy?


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brew_ny

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So my understanding was that most old 3-wire dryer outlets don't have a ground running to the panel at all?
the ground wire is running back to the panel on your outlet, yes if you want to a four wire outlet hookup that way

but when in doubt get a electrician to look at it

good luck

S_M
 

P-J

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The outlet is a 3 wire outlet (Hot-red, Hot-black, Neutral-white) The cable feeding it a 4 wire cable (Hot-red, Hot-black, Neutral-white and ground [bare copper wire]). It is what it is...

P-J
 

brew_ny

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The outlet is a 3 wire outlet (Hot-red, Hot-black, Neutral-white) The cable feeding it a 4 wire cable (Hot-red, Hot-black, Neutral-white and ground [bare copper wire]). It is what it is...

P-J

that is what it is indeed the bare does more then likely run back to a ground bar in the main panel

could you use it in a four wire plug? when in doubt have a electric look

that being said I am not sure what the OP here is even trying to do

would I wire a four wire plug with what he has if I thought I needed one maybe

but again I am no sparky :)

all the best

S_M
 

P-J

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that is what it is indeed the bare does more then likely run back to a ground bar in the main panel

could you use it in a four wire plug? when in doubt have a electric look

that being said I am not sure what the OP here is even trying to do

would I wire a four wire plug with what he has if I thought I needed one maybe

but again I am no sparky :)

all the best

S_M
Yes indeed, you could easily change the outlet to a 4 prong outlet. However: if it would be used to also power a dryer, the dryer would need to be rewired to accomodate a 4 wire power inlet and the plug for it would need to be changed as well.

P-J
 

brew_ny

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Yes indeed, you could easily change the outlet to a 4 prong outlet. However: if it would be used to also power a dryer, the dryer would need to be rewired to accomodate a 4 wire power inlet and the plug for it would need to be changed as well.

P-J

indeed it would need to be rewired :)

but again I am not sure what the OP is looking to do in the end

all the best

S_M
 
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ingchr1

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I guess my question is, do you think this ground leads back to the panel and therefore changing it to a 4-wire outlet would be very easy?
Edit: You could check the wire to ground by perform a continuity check between the ground at the dryer receptacle and a ground in another nearby outlet. Since the grounds should all be common at the panel. Prior to performing the continuity check, verify no voltage is present on the wires you are measuring continuity on.

This assumes you have a meter and your leads are long enough.

Changing the receptacle and your dryer configuration is fairly easy, just did mine.
 

Brad2287

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Edit: You could check the wire to ground by perform a continuity check between the ground at the dryer receptacle and a ground in another nearby outlet. Since the grounds should all be common at the panel. Prior to performing the continuity check, verify no voltage is present on the wires you are measuring continuity on.

This assumes you have a meter and your leads are long enough.

Changing the receptacle and your dryer configuration is fairly easy, just did mine.
Also if the leads are not long enough you can use an extension cord in order to extend the ground to where the dryer outlet is.

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