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#41577 - 08/31/04 11:48 AM Rangs/Dryer plugs 3 and 4 prong  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
They are gradually converting over to 4 prong plugs for electric ranges and dryers. Not much good on the older 2 wire with ground circuits. Is the the new code requiring all 3 wire with ground circuits be run?


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#41578 - 08/31/04 11:57 AM Re: Rangs/Dryer plugs 3 and 4 prong  
CTwireman  Offline
Member
Joined: Feb 2002
Posts: 840
Connecticut, USA
What code edition are you using in AZ? The change to 4 wire was first required in the 1996 NEC, so this isn't exactly new.

To answer your question, from the 1996 NEC on requires 4 wire circuits in all new installations. Old 3 wire circuits are permitted to remain.

A feed to a dryer or range that is 2-wire with a bare ground has always been a code violation, and should be replaced no matter what.

Peter

[This message has been edited by CTwireman (edited 08-31-2004).]


Peter

#41579 - 08/31/04 11:59 AM Re: Rangs/Dryer plugs 3 and 4 prong  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Al,

Yes, all new Electric Range and Dryer circuits installed must be 4 wire. This does not mean that older 3 wire (that were code-compliant) circuits must be replaced.

Bill


#41580 - 08/31/04 12:01 PM Re: Rangs/Dryer plugs 3 and 4 prong  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Peter,

sorry, I didn't see your reply.

[Linked Image]
Bill


#41581 - 09/01/04 12:45 AM Re: Rangs/Dryer plugs 3 and 4 prong  
aldav53  Offline
Member
Joined: Aug 2001
Posts: 545
Chandler, AZ USA
Peter, if older 2 wire circuits were a code violation, then how would they be wired to an older 3 prong plug with 2 hots and a center ground? Which is what was used everywhere.
The center conductor (ground) was used as a current carring neutral for any 120 volt on the dryer.


The Golden Rule - "The man with the gold makes the rule"

#41582 - 09/01/04 01:03 AM Re: Rangs/Dryer plugs 3 and 4 prong  
caselec  Offline
Member
Joined: Apr 2002
Posts: 558
San Jose, CA
Older 3-wire range (10-50) and dryer (10-30) receptacles have 2 hots and a neutral but no equipment ground. The neutral was used to ground the non current carrying metal parts of the appliance. As Peter said it has never been code compliant to use an equipment ground as the neutral.

Curt


Curt Swartz

#41583 - 09/01/04 02:16 AM Re: Rangs/Dryer plugs 3 and 4 prong  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Anyone ever notice that new ranges and dryers are sold without a cord... And instructions for installing both a 3 and a 4 wire cord?

A few times "Appliance Installers" have shown up with only 3-wire cords. (Look at me funny as I explain it too them.)And try to get me to change the receptical to fit thier 3-wire cord.


Mark Heller
"Well - I oughta....." -Jackie Gleason

#41584 - 09/01/04 06:46 AM Re: Rangs/Dryer plugs 3 and 4 prong  
Speedy Petey  Offline
Member
Joined: Aug 2003
Posts: 173
Upstate, NY
if older 2 wire circuits were a code violation, then how would they be wired to an older 3 prong plug with 2 hots and a center ground?
It was done because people who didn't know what they were doing wired them. Unfortunately this does happen.

Which is what was used everywhere
Just because it was done everywhere doesn't mean it was ever legal.

The center conductor (ground) was used as a current carring neutral for any 120 volt on the dryer.
Again, never was code and is one of the more dangerous mistakes made. Especially with a large metal box usually associated with water.


Speedy Petey

"Anyone who has never made a mistake has never tried anything new." -Albert Einstein

#41585 - 09/01/04 07:58 AM Re: Rangs/Dryer plugs 3 and 4 prong  
winnie  Offline
Member
Joined: Sep 2003
Posts: 649
boston, ma
I believe that there a bit of confusion.

For large 240V appliances (ranges and dryers), old code permitted the use of the use of the same conductor for both grounding the frame and neutral return of 120V loads. This is _not_ necessarily a violation.

I don't know the details of older code, but in the 2002 code, there are specific descriptions of when such a circuit make be continued to be used. In particular, the ground/neutral wire must either be insulated, or the cable must be service entrance cable. Type NM with two insulated conductors and a bare ground would be explicitly prohibited. But if the install was done using Type MC cable with an insulated ground, then my read says that it can still be used.

All _new_ installs must correctly separate ground and neutral.

I don't see how it could ever be appropriate to connect a three conductor cable to a 4 slot receptacle. Ground and neutral would be shared, but this would be hidden back in the wall.

-Jon


#41586 - 09/01/04 08:35 AM Re: Rangs/Dryer plugs 3 and 4 prong  
electricman2  Offline
Member
Joined: Nov 2003
Posts: 269
Thomasville, NC USA
Anybody want to speculate how many dryers are out there supplied with 10-2 romex? I have seen a few.


John

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