2023 250.140 Frames of Ranges and Clothes Dryers

[@chrisf3875]

I do recall doing my cod update at this time, it was explained, there was a gentlemen that did some wonderful research and wrote a paper on this. about how this three and four wire situation manifested itself. And basically it came about during WW2 there was a severe copper shortage and so they allowed the neutral and grounding wire to be one to save the copper wire in the cable. But after the war it never was undone and as time marched on no one remembered why,until this gentleman did the research and wrote the paper. Curious to see if anyone has come across this paper or have heard this. Thanks

[@garbo8962]

Retired after 50 years and often wondered how they got away with the bare wire feeding the neutral & ground on electric dryer & ranges. Thanks. Did electrical work in a doctors house that he had to get permission to build it during g WW2.

[@Sparky-ww5re]

Yes I did some research, it's very obscure but from what little info I could gather, it was the Tentative Interim Amendment 53 put in effect in July 1942 and supposedly an effort to conserve raw materials during the war. This is where the allowance for grounding the frames of ranges to the grounded (neutral) circuit conductor began. This permission was extended to clothes dryers in 1953 and of course remained that way until 1996 although in some jurisdictions it wasn't until closer to the early 2000s when the rule was widely enforced.

[@chrisf3875]

Thanks for that, interesting they extended it to the dryer in the 50's. I do get the logic when you come from the main service. But the whole thing is just a bad habit. Been in situations like having a 50 unit complex. With all the units having sub- panels(being federal pacifics, upgrading them). The original electrician didn't understand how the rule worked,nor did the inspector pick up on it. I'm glad they removed this allowance. We'll all be dealing with the ramifications for a long time.

[@garbo8962]

Can never forgive the NEC or who ever allowed the bare ground wire on type NM cable to be a dual function connection that be supp!ting the neutral and ground. Now what 75 years later you would think that lazy cheap appliance companies would produce some electric dryers that do not require a neutral by installing a $8 transformer to supply either 120 or 24 volts for controls & LED drum light and a 240 volt drum motor. The few extra dollars would be cheaper then running 10/3 & more expensive 4 wire 250 receptacle.

[@Sparky-ww5re]

Oh tell me about it. At the company I work for we wire custom homes and some (but not all of) the larger built in microwave ovens and steam wall ovens we install plug into a NEMA 6-20R, and yes these ovens have incandescent oven lights. Other's call for a 12/3 w/G cable and are hardwired, identical features but different manufacturer.

[@Sparky-ww5re]

It would be hilarious so to speak if you needed to replace a dryer motor and discovered the original was a dual voltage motor set up for 120V instead of 240V

[@mattv5281]

Agreed. It's ridiculous that a range or dryer needs 120V for anything. And now people are going around installing NEMA 14-50 receptacles for EV charging "because it's the standard". That 6 or 8 gauge neutral will only ever carry a few milliamps for the control electronics, and if an EVSE truly requires a neutral for some reason, the person who designed it is an idiot.

[@arickbakken]

Was 10/2 with bare conductor used for old dryer installations? My 1980s house used 10-3 ungrounded (black, red, white, no bare) into a 10-30R.

[@noahjones8510]

What do you do with the bare grounded conductor at the outlet in the kitchen if the cable is landed in a metal box? Does the box need to be bonded to the grounded conductor?

[@electricianron_New_Jersey]

Ryan, when are you coming back to NJ-IEC to do continuing education for us? I love this discussion about the 3-wire vs 4-wire.

[@RyanJacksonElectrical]

Tell the chapter to bring me back. I'd love to do another class in Jersey

[@brianerock]

As I pointed out for the 1996 NEC® Public Comment (for other than mobile homes and RVs that never permitted the grounded conductor to serve as the EGC), the reason for electric range ovens/ranges and clothes dryer to use the grounded conductor as the EGC was to save copper for »the “war effort” of WWII«. WWII ended in 1945! In 1996, it was LONG OVERDUE to stop this practice of compromising the purpose of using an EGC discrete of the grounded conductor.

[@saltyroe3179]

So my gas dryer and gas stove that require only 110volt single phase are safe because they are fed by hot, neutral and case ground? Neutral and case ground are bonded at the breaker box? Cannot imagine replacing gas appliances with electric in old housing.

[@playnationtoday]

So when you do the described service upgrade and the interior panel is now a sub-panel im assuming this insulated conductor gets landed on the neutral bar….?

[@paul4800]

Correct. "The grounded conductor shall be insulated or field covered within the supply enclosure with listed insulating material, such as tape or sleeving to prevent contact of the uninsulated conductor with any normally non-current-carrying metal parts." Must go to neutral bar.

[@ElectricalCodeCoach]

This is pure gold! Thanks Ryan!!

[@JoshMarriott-s9w]

Ranges and dryers have lcd screens which means they should just use 240 transformer so we dont need a neutral. Its 2024

[@jimmiegill3981]

It said shrink tube or tape?

[@paul4800]

"tape or sleeving"

[@Sparky-ww5re]

That's some nice clarification. BTW It was the 1996 NEC that prohibited using 3 wire dryer and range setups, local codes may have banned them sooner of course, and for those jurisdictions that adopted each code cycle later 3 wire setups could have lasted into the early 2000s

[@Fazer07]

Would you have to have the shrink tube colored white? It seems odd to use black shrink tube on the bare conductor.

[@paul4800]

As a grounded conductor, 200.7 rules would apply- white or white stripes.