# Dryer plugs, 3 to 4 prong



## Going_Commando (Oct 1, 2011)

Neither are legit. Just use the proper cord for the # of wires feeding the dryer receptacle.


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## handyandy (Jan 3, 2012)

alselec53 said:


> Changing a 3 conductor, 2 hot legs and a ground, old style (3 prong) 30a dryer outlet to a 4 prong outlet to work with a 4 prong dryer plug. Whats the best way to do this? Use a 3 prong cord instead? Or put a jumper in the 4 prong outlet (neutral to ground?) The neutral and ground are separate at the dryer with the newer dryers I believe. Not clear on this.
> Also, if there is a 4 conductor at the outlet, can you legally tie the neutral and ground together at the outlet to work with a 3 prong? and 3 prong dryer cord?
> 
> Thanks,


If 3 prong is existing outlet I would replace cord and plug on dryer.


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## alselec53 (Jan 4, 2012)

*dryer recept*

The people that install dryers change them all the time, 3 to 4 prong, I could never figure how this could be legal.
If a 3 prong cord is put on a new dryer, then you would have no neutral or no ground. Unless you jumpered them together at the dryer. That can't be right?


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## electrictim510 (Sep 9, 2008)

alselec53 said:


> The people that install dryers change them all the time, 3 to 4 prong, I could never figure how this could be legal.
> If a 3 prong cord is put on a new dryer, then you would have no neutral or no ground. Unless you jumpered them together at the dryer. That can't be right?


3 wire electrical wiring and 4 wire capable dryer can only be wired by a 3 wire cord. If it NEEDS a 4 wire for warranty reasons or whatever other reason then it needs to be wired from panel that way.


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## handyandy (Jan 3, 2012)

alselec53 said:


> The people that install dryers change them all the time, 3 to 4 prong, I could never figure how this could be legal.
> If a 3 prong cord is put on a new dryer, then you would have no neutral or no ground. Unless you jumpered them together at the dryer. That can't be right?


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## macmikeman (Jan 23, 2007)

The thing also most forgotten about this is that the three wire cable runs were supposed to be from the service, not from subpanels. So if an existing 3 wire run is present for the dryers in question, and it is run from a subpanel , instead of having been run as required by older codes from the main service panel , the run should be replaced with a 4 conductor cable run, and a 4 conductor cord and outlet be installed to the unit.


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## alselec53 (Jan 4, 2012)

*dryer recept 3 to 4 wire*

So a 3 wire coming from a main panel cannot be connected to a 4 wire dryer outlet. Any way you look at it the neutral and ground would have to be tied together either at the outlet or the at the dryer. None of this seems legal unless you run a new 4 wire from the panel.
Even converting 4 to 3 wire you would have to tie the neutral and the ground together at the outlet or dryer. 
How can I install a 4 wire outlet on an old wire system to a new 4 wire dryer? Can't be done legally to me?


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## alselec53 (Jan 4, 2012)

*dryer recept 3 to 4 wire*

Can't seem to get a clear answer on this.


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## alselec53 (Jan 4, 2012)

*dryer recept 3 to 4 wire*

handyandy, what do you do with the 4th ground wire in the outlet. The dryer ground can be left connected or isolated (disconnected), but you still have the extra ground prong in the outlet.


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## macmikeman (Jan 23, 2007)

alselec53 said:


> So a 3 wire coming from a main panel cannot be connected to a 4 wire dryer outlet. Any way you look at it the neutral and ground would have to be tied together either at the outlet or the at the dryer. None of this seems legal unless you run a new 4 wire from the panel.
> Even converting 4 to 3 wire you would have to tie the neutral and the ground together at the outlet or dryer.
> How can I install a 4 wire outlet on an old wire system to a new 4 wire dryer? Can't be done legally to me?


Let me get this straightened out for you. "If" you have an existing 3 wire dryer outlet that you are not relocating and you are changing your existing dryer you can install the new dryer into that same location by installing a 3 wire whip on it, (providing the branch circuit supply originates at the main panelboard where the service is bonded) but there must be a neutral-frame bond in the dryer. If all these conditions are not met, then you have to run a new 4 wire branch circuit and install a 4 wire outlet, and a 4 wire whip, and remove the bonding strap between the dryer frame and the neutral connection lug inside the dryer. I hope I worded that in a way anybody can understand it, I realize its kinda long.


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## alselec53 (Jan 4, 2012)

*dryer recept 3 to 4 wire*

That seems to make sense, so you really cant convert a 3 to 4 wire legally since there is no neutral and ground going back to the panel, unless you run a new 4 wire circuit.
But I guess you could convert a 4 to 3 wire, (newer house to older dryer), by tying the neutral and ground together at the outlet, which is kinda redundent.. is that legal?

Thanks,


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## handyandy (Jan 3, 2012)

macmikeman said:


> Let me get this straightened out for you. "If" you have an existing 3 wire dryer outlet that you are not relocating and you are changing your existing dryer you can install the new dryer into that same location by installing a 3 wire whip on it, (providing the branch circuit supply originates at the main panelboard where the service is bonded) but there must be a neutral-frame bond in the dryer. If all these conditions are not met, then you have to run a new 4 wire branch circuit and install a 4 wire outlet, and a 4 wire whip, and remove the bonding strap between the dryer frame and the neutral connection lug inside the dryer. I hope I worded that in a way anybody can understand it, I realize its kinda long.


You explained that very well. I though I explained it good enough for an electrician to understand.


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## CraigV (May 12, 2011)

For this use, 3-wire circuits are permitted from subpanels as long as SE cable (bare neutral) is *not* used, and the grounded conductor is #10 or larger Cu, or #8 or larger Al. For subs, 3-wire has to have an insulated neutral.

I think the pertinent NEC articles are 250.140 and 250.142.


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## CraigV (May 12, 2011)

alselec53 said:


> That seems to make sense, so you really cant convert a 3 to 4 wire legally since there is no neutral and ground going back to the panel, unless you run a new 4 wire circuit.
> But I guess you could convert a 4 to 3 wire, (newer house to older dryer), by tying the neutral and ground together at the outlet, which is kinda redundent.. is that legal?
> 
> Thanks,


I've wired driers since the late 70's and all had provision in one form or another for either 3- or 4-wire cordsets.


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## macmikeman (Jan 23, 2007)

alselec53 said:


> That seems to make sense, so you really cant convert a 3 to 4 wire legally since there is no neutral and ground going back to the panel, unless you run a new 4 wire circuit.
> But I guess you could convert a 4 to 3 wire, (newer house to older dryer), by tying the neutral and ground together at the outlet, which is kinda redundent.. is that legal?
> 
> Thanks,


Nope. The dryer outlet must be a 4 wire since I think early 90's versions of code, Ken's gonna know exactly which cycle it came in, and you have to wire the dryer to the outlet, not the outlet to the dryer in that particular situation you are now asking about.


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## alselec53 (Jan 4, 2012)

*dryer recept 3 to 4 wire*

Ok.. if you think about it, the older 3 wire dryer circuits had a SE (non insulated) ground, but was carrying current for the motor usually 120 volt - not heater element of course. So I guess you would be disconnecting the ground tab in the 4 wire dryer, hooking it to the 4 wire dryer cord, isolating the ground, but it would still use the 3 wire non insulated ground at the receptacle going back to the panel. Either having no ground/neutral, 4 prong, or jumpering grd & neutral.
I know either way it works, but doesn't seem correct?


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## 220/221 (Sep 25, 2007)

alselec53 said:


> Whats the best way to do this? Use a 3 prong cord instead? Thanks,


..Yes


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## crazyboy (Nov 8, 2008)

alselec53 said:


> Ok.. if you think about it, the older 3 wire dryer circuits had a SE (non insulated) ground, but was carrying current for the motor usually 120 volt - not heater element of course. So I guess you would be disconnecting the ground tab in the 4 wire dryer, hooking it to the 4 wire dryer cord, isolating the ground, but it would still use the 3 wire non insulated ground at the receptacle going back to the panel. Either having no ground/neutral, 4 prong, or jumpering grd & neutral.
> I know either way it works, but doesn't seem correct?


There is no either way. As stated before if it is an existing installation install a cord on the appliance that matches the receptacle. How long have you been doing in the trade?


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## 220/221 (Sep 25, 2007)

Use the 3 wire cord and *make sure the ground jumper on the dryer is in place.*


If you used a 4 wire cord, left the jumper in place or jumped N-G at the recep, it would *function* the same but would not be *proper* because someone in the future would assume that 4 wire recep meant 4 wire circuit.


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## alselec53 (Jan 4, 2012)

*Dryer recept*

Yes i came to that conclusion. About 30 years in trade, including devry electronics, residential, comm, ind machine wiring, guess im getting forgetful at 58. Time for a refresher code class.


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## alselec53 (Jan 4, 2012)

*3 wire to 4 wire range convert*



crazyboy said:


> There is no either way. As stated before if it is an existing installation install a cord on the appliance that matches the receptacle. How long have you been doing in the trade?


Too Long..
So, the customer has an old wired 3 prong plug. So I leave that. He has a new 4 prong range going in. My only choice is to add a 3 wire to the range (or if it was a dryer) to it, making sure the range neutral is grounded to the frame.
Also, If its a 4 wire pigtail coming off the range, then I add a 3 wire whip?
Still seems like it would be tieing a current carrying neutral to a ground.
Its there a picture I can find? How can this simple thing not make sense?


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## chicken steve (Mar 22, 2011)

macmikeman said:


> The thing also most forgotten about this is that the three wire cable runs were supposed to be from the service, not from subpanels. So if an existing 3 wire run is present for the dryers in question, and it is run from a subpanel , instead of having been run as required by older codes from the main service panel , the run should be replaced with a 4 conductor cable run, and a 4 conductor cord and outlet be installed to the unit.


Because it effectively becomes a bond to Noodle in said_ overlooked_ situations

~CS~


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## 220/221 (Sep 25, 2007)

Holy late reply!





alselec53 said:


> So, the customer has an old wired 3 prong plug. So I leave that.
> 
> He has a new 4 prong range going in. My only choice is to add a 3 wire *pigtail *to the range (or if it was a dryer) to it, making sure the range neutral is grounded to the frame.


Yes


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## HARRY304E (Sep 15, 2010)

alselec53 said:


> Changing a 3 conductor, 2 hot legs and a ground, old style (3 prong) 30a dryer outlet to a 4 prong outlet to work with a 4 prong dryer plug. Whats the best way to do this? Use a 3 prong cord instead? Or put a jumper in the 4 prong outlet (neutral to ground?) The neutral and ground are separate at the dryer with the newer dryers I believe. Not clear on this.
> Also, if there is a 4 conductor at the outlet, can you legally tie the neutral and ground together at the outlet to work with a 3 prong? and 3 prong dryer cord?
> 
> Thanks,


Run 10/3 Romex from the panel to the dryer hook it up. Roll up the 10/2 Romex and sell it for scrap.


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## Shockdoc (Mar 4, 2010)

I do this every once in a while. I cheat a jump a ground from the #12 laundry ckt.


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## gold (Feb 15, 2008)

Shockdoc said:


> I do this every once in a while. I cheat a jump a ground from the #12 laundry ckt.


I don't know if this is legal or not but it seems to me bringing an EGC from an electrically continuous plumbing pipe that is well bonded to the GEC to upgrade from 3 wire to for would be safer.

I never liked the neutral/ground bond in an appliance. Especially if its fed off a sub panel as Mike said.


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## BytheBook (May 29, 2013)

I think there was an exception somewhere that if you insulated the exposed ground/neutral (3rd wire) in the SEU (at the panel and the jbox at dryer) the g/n would be considered insulated and just bond the g/n


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## papaotis (Jun 8, 2013)

the local B.I. once told me you cant have too many grounds, but isnt one enough?:001_huh:


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## RIVETER (Sep 26, 2009)

alselec53 said:


> Changing a 3 conductor, 2 hot legs and a ground, old style (3 prong) 30a dryer outlet to a 4 prong outlet to work with a 4 prong dryer plug. Whats the best way to do this? Use a 3 prong cord instead? Or put a jumper in the 4 prong outlet (neutral to ground?) The neutral and ground are separate at the dryer with the newer dryers I believe. Not clear on this.
> Also, if there is a 4 conductor at the outlet, can you legally tie the neutral and ground together at the outlet to work with a 3 prong? and 3 prong dryer cord?
> 
> Thanks,


The neutral and the grounding conductor can only be connected together at the service disconnect.


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## wendon (Sep 27, 2010)

Shockdoc said:


> I do this every once in a while. I cheat a jump a ground from the #12 laundry ckt.


Are you


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## buddhakii (Jan 13, 2011)

250.140 in 2005 NEC has all the info you need. Don't do resi anymore but my guess is this rule has not changed.


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## Shockdoc (Mar 4, 2010)

Goldagain said:


> I don't know if this is legal or not but it seems to me bringing an EGC from an electrically continuous plumbing pipe that is well bonded to the GEC to upgrade from 3 wire to for would be safer.
> 
> I never liked the neutral/ground bond in an appliance. Especially if its fed off a sub panel as Mike said.


I avoid the plumbing now that lately it seems every plumber or handyman is replacing sections with PEX. The #12 although undersized to NEC code will recieve a 30 amp surge w/o breaking a sweat and is sufficient enough to trip the breaker on a ground fault. I'd much rather have a 4 wire system over a 3 wire system. It's been a violation to feed a 120/240 volt appliance with a 3 wire for many years, but like mike I have come across it also such as 8/2 SE feeding a range pulled from a 100 amp sub from a metermain set up.


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