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#78165 08/22/01 08:32 PM
Joined: Aug 2001
Posts: 545
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aldav53 Offline OP
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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 08:43 PM
Joined: Jul 2001
Posts: 43
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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.

#78167 08/22/01 08:54 PM
Joined: Oct 2000
Posts: 5,392
S
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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]

#78168 08/22/01 08:56 PM
Joined: Oct 2000
Posts: 2,749
Member
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
#78169 08/22/01 10:23 PM
Joined: Dec 2000
Posts: 4,289
Member
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).]

#78170 08/23/01 01:35 PM
Joined: May 2001
Posts: 717
G
Member
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.

#78171 08/23/01 09:15 PM
Joined: Oct 2000
Posts: 5,392
S
Member
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]

#78172 08/25/01 06:02 PM
Joined: Aug 2001
Posts: 7,520
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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.

#78173 08/25/01 08:27 PM
Joined: Mar 2001
Posts: 2,056
R
Member
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.

#78174 08/25/01 09:13 PM
Joined: May 2001
Posts: 717
G
Member
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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