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dryers #78165
08/22/01 07:32 PM
08/22/01 07:32 PM
A
aldav53  Offline OP
Member
Joined: Aug 2001
Posts: 545
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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Re: dryers #78166
08/22/01 07:43 PM
08/22/01 07:43 PM
M
mickky  Offline
Member
Joined: Jul 2001
Posts: 43
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.

Re: dryers #78167
08/22/01 07:54 PM
08/22/01 07:54 PM
S
sparky  Online Content
Member
Joined: Oct 2000
Posts: 5,344
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!

[Linked Image]

Re: dryers #78168
08/22/01 07:56 PM
08/22/01 07:56 PM
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
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.


Joe Tedesco, NEC Consultant
Re: dryers #78169
08/22/01 09:23 PM
08/22/01 09:23 PM
electure  Offline

Member
Joined: Dec 2000
Posts: 4,264
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 [Linked Image]
(I really do hope they're careful)

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

Re: dryers #78170
08/23/01 12:35 PM
08/23/01 12:35 PM
G
George Corron  Offline
Member
Joined: May 2001
Posts: 717
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.

Re: dryers #78171
08/23/01 08:15 PM
08/23/01 08:15 PM
S
sparky  Online Content
Member
Joined: Oct 2000
Posts: 5,344
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
[Linked Image]

Re: dryers #78172
08/25/01 05:02 PM
08/25/01 05:02 PM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
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.

Re: dryers #78173
08/25/01 07:27 PM
08/25/01 07:27 PM
R
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
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.

Re: dryers #78174
08/25/01 08:13 PM
08/25/01 08:13 PM
G
George Corron  Offline
Member
Joined: May 2001
Posts: 717
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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