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#91440 - 01/16/05 01:57 PM GFI / washing machines
luckyshadow Offline
Member
Registered: 01/04/05
Posts: 305
Loc: Maryland USA
Question
Why not require GFI receptacles for washing machines ?
We need them on spas,hot tubs, garages, basements commercial kitchens, 6' from sinks, outside etc etc.
Why not the 4' tall x 3' wide x 3' deep box of steel we fill to the top with water
Think about it
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#91441 - 01/16/05 02:04 PM Re: GFI / washing machines
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
IMO it will eventually be required.

I believe most of the present GFCI locations have had a 'body count' available to justify the requirement.

If someone can show the need by way of electrocutions from washing machines it would probably get into the NEC.

Quote:
6' from sinks


That is not all sinks, only 'wet bar sinks'
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#91442 - 01/16/05 03:03 PM Re: GFI / washing machines
Physis Offline
Member
Registered: 12/28/04
Posts: 86
Loc: Burlingame, Ca. USA
I disagree with you Bob, about the body count.

I think if GFI's can get past the inductive load problems the code writers will have less reason to not require them. Given better and less expensive technology in the future I would expect more requirement with or without more dead people.

For right now I would agree that they're not wanted where they're not needed because they can cause more problems than they solve.
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Sam, San Francisco Bay Area
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#91443 - 01/16/05 03:05 PM Re: GFI / washing machines
Physis Offline
Member
Registered: 12/28/04
Posts: 86
Loc: Burlingame, Ca. USA
Hey, you weren't a moderator. Were you?
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Sam, San Francisco Bay Area
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#91444 - 01/16/05 03:14 PM Re: GFI / washing machines
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Sam I agree to some extent.

But IMO the NEC is not really worried about nuisance tripping as evidenced by the commercial kitchen requirement. That includes refrigerators.

Also consider that pool pumps and the all the power tools on a job site work fine on a GFCI.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#91445 - 01/16/05 03:19 PM Re: GFI / washing machines
Physis Offline
Member
Registered: 12/28/04
Posts: 86
Loc: Burlingame, Ca. USA
I like the job site tools one the best. I don't know how many times Iv'e been told that GFI's never nuisance trip because of that.
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Sam, San Francisco Bay Area
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#91446 - 01/16/05 03:23 PM Re: GFI / washing machines
Physis Offline
Member
Registered: 12/28/04
Posts: 86
Loc: Burlingame, Ca. USA
That is a good point though, and I agree the NEC guys don't care too much, but, is there like a difference in manufacturer or something that accounts for some applications not being a problem while others are?
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Sam, San Francisco Bay Area
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#91447 - 01/16/05 03:34 PM Re: GFI / washing machines
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Quote:
I like the job site tools one the best. I don't know how many times Iv'e been told that GFI's never nuisance trip because of that


Sam I am not sure what you mean here.

I believe that almost all GFCI tripping can be traced to a 'real' problem.

Every appliance is likely to have leakage current, running to many items from on GFCI is not a good plan as the cumulative leakage current.

Long branch circuits can also cause problems.

Then of course you could just have a faulty appliance.

My sump pump in my basement happens to be on a GFCI and it runs a 3 or 4 times an hour when it rains. It has never tripped the GFCI. When it does I will buy a new pump.

The engineered prints I work from will specify a separate GFCI receptacle for every location that needs one, no using GFCI breakers, or coming off the load side of another GFCI outlet.

This is also how we do job temps, normal breakers with a GFCI receptacle at the point of use.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#91448 - 01/16/05 03:55 PM Re: GFI / washing machines
Physis Offline
Member
Registered: 12/28/04
Posts: 86
Loc: Burlingame, Ca. USA
Well, you seem to be on the side of those who would say that GFI's wont nuisance trip now.

Will they or wont they?

Some of those who say that they wont will site as evidence that they can run power tool from them.

If it is a current leak it is necessarilly not a nuisance trip.

I will say this much. I don't really know what causes the nuisance tripping. But my instinct tells me it's not always current outside the intended path.
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Sam, San Francisco Bay Area
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#91449 - 01/16/05 05:52 PM Re: GFI / washing machines
Electric Ian Offline
Member
Registered: 02/10/04
Posts: 133
Loc: MA, USA
------------------------------------
I don't really know what causes the nuisance tripping.
-----------------------------------

In a word, inductance. A GFI trips when the source current to the load does not equal the return current from the load. One of the characteristics of inductance is that the current thru such a load cannot change instantaneously. Thus if you provide a unit step of source current to an inductive load, the return current from that load will have an inherent rise time (delay). During this delay there will be a difference in current between the source and the return. This difference in current is not leakage current to ground but rather a difference due to the characteristics of inductance. Nonetheless, the GFI doesn't know that and will theerfore (nuisance) trip. How much difference in current there is and the duration of the delay is dependent on the inductive
characteristics of the load.
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