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#78165 - 08/22/01 05:32 PM dryers
aldav53 Offline
Member

Registered: 08/22/01
Posts: 547
Loc: Chandler, AZ USA
Most 240v dryers have a 3 prong plug, but actually should have a 4 prong to isolate the neutral from the ground, since the motor and timer usually runs on 120v. Right?
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#78166 - 08/22/01 05:43 PM Re: dryers
mickky Offline
Member

Registered: 07/22/01
Posts: 48
Loc: toronto
 Quote:
Originally posted by aldav53:
Most 240v dryers have a 3 prong plug, but actually should have a 4 prong to isolate the neutral from the ground, since the motor and timer usually runs on 120v. Right?

All dryers that I have seen up here in Ontario in recent years have a 4-prong plug, for the reasons you state.

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#78167 - 08/22/01 05:54 PM Re: dryers
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
I think it's a 96' code, anyways it's fairly recent. All the appliance men now despise us for the NEC's meddeling into this. A large percentage of cord swaps result in the N&G jumper still intact. But sales are up for pigtails!


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#78168 - 08/22/01 05:56 PM Re: dryers
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
They are required to be 4 wire systems for new circuits, see the 1999 NEC in Section 250-140. Frames of Ranges and Clothes Dryers.
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#78169 - 08/22/01 07:23 PM Re: dryers
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
Sparky,
Let those sniveling appliance men lose a neutral/grd connection in a panel or recp sometime.
Then watch their eyes bug out as they lean their big bare bellies over the dryer and hang on to the washing machine water pipes to reach their beloved 3 wire plug
(I really do hope they're careful)

[This message has been edited by electure (edited 08-22-2001).]

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#78170 - 08/23/01 10:35 AM Re: dryers
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
The history on this is pretty pathetic. The 96 code changed a long standing rule, until then the frames of dryers could be grounded with the neutral. Why, you may ask ? It was allowed during WW2 to save copper and not many troubles were reported, finally, based on evidence (people literally dying) it was addressed in the 96 code. Unfortunately, there are LOTS of installations that grandfather. There were too many instances of housewives (or children playing) behind the dryer (cleaning,chasing a ball....) touch the frame of the dryer, and lean into a water pipe, now you're carrying the neutral current. Too darned many were seriously shocked and more than one expired.

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#78171 - 08/23/01 06:15 PM Re: dryers
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
LOL !
well they sure snivel up a storm, especially when i get to break the news , which has happened quite often.

It's ironic that the metal saved , which was probably dropped on the enemy during WW2, may quite likley be finding it's way back as those cheapo appliances

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#78172 - 08/25/01 03:02 PM Re: dryers
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Can you confirm that I have interpreted the rules correctly here?

My understanding of the NEC (at least as it was until recetly) is that when a range or dryer outlet was wired directly to the main panel, then only a 3-wire outlet & cord (two hot plus neutral) was needed, the frame being grounded to the neutral.

If the branch was run from a sub-panel (in which N & G are separate), then a 4-wire hook-up was required to provide separate neutral & ground. Correct?

First time I read about this, it took some getting used to, as on our system we never ground an appliance frame to the neutral.

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#78173 - 08/25/01 05:27 PM Re: dryers
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
 Quote:
Originally posted by pauluk:
Can you confirm that I have interpreted the rules correctly here?

My understanding of the NEC (at least as it was until recetly) is that when a range or dryer outlet was wired directly to the main panel, then only a 3-wire outlet & cord (two hot plus neutral) was needed, the frame being grounded to the neutral.

If the branch was run from a sub-panel (in which N & G are separate), then a 4-wire hook-up was required to provide separate neutral & ground. Correct?

First time I read about this, it took some getting used to, as on our system we never ground an appliance frame to the neutral.



That is correct.

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#78174 - 08/25/01 06:13 PM Re: dryers
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
As of the 1996 NEC, you can use a 3 wire cord for existing installations only ( see 250-140 also 134,138 in the 99 nec) new installations require a 4 wire cord with the neutral NOT connected to the frame of dryers or ranges.

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