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?

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).]

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

Peter,

sorry, I didn't see your reply.


Bill

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.

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

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.

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.

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

Anybody want to speculate how many dryers are out there supplied with 10-2 romex? I have seen a few.

caselec,
The neutral was also used to carry current carring loads, it would have to, to run the 120v loads.

Aldav53,
You are correct that the neutral conductor will have current on it. In your original post you were talking about dryer/range receptacles supplied by 2 hots and an equipment ground which is and always has been a non compliant installation.

Curt

Read Winnie's (jon's) post, I believe he is correct. Two hots and a bare conductor were legal as long as it was SEC. An old timer told me it was permitted during the 1940's to conserve metal for the war effort. You never know about those old timer stories though.
Pat

The bare conductor of type SE cable is approved for use as a neutral conductor. If used as a neutral it must be connected to the neutral buss. The bare conductor of Type NM cable is not approved for use as a neutral conductor. Using the armor of AC cable or a metal raceway for the neutral conductor has never been permitted.

I have also heard that the reason the neutral conductor was permitted to also serve as the EGC was to conserve metal. Some time ago I had a discussion about this with Bennie Palmer and he said that it was not done to conserve metal.

Curt

Grounded conductor has to be covered not bare except for se cable. I just had a problem with a dryer I went to troubleshoot. It was a 10/2 feeding the recep & the grounding conductor was used as the 120v potential for the timer loads, Lts. etc; As I had the recep out, I plugged in the dryer & I lost one les and picked up 240v on the other. There is a break in the grounding conductor somewhere. I have to run a 10/3 now & change unit to a 4 prong whip. I'm glad the code wants the noodl & EGC separated.

The FD got a new washer/dryer combo in today, and the boss asked me if I "knew how to wire it up" . Told him I could figure it out.

Guess which cord came with it?


The old 3-prong (10-30, IIRC) ...

So much for industry compliance.

Doug, my guess is the manufacturer ass-u-me-s that it's automatically going to be going into a house with an old three-wire installation.

If anything, the manufacturer should include both cord-sets and detailed instructions for installing either one depending on what is called for by the end user's situation.

It wouldn't cost the manufacturer THAT much to toss in an extra cordset.