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Joined: Dec 2000
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A neighbor wants to put a 60A subpanel in his detached garage, about 30' from the house. He's doing it himself, has already run a UG 1" conduit with 3 #4, & a #8 EGC. AHJ said he's required to install another grounding electrode @ the garage, but why?? I don't have a good answer for him. His reasoning is that if the sub was on the fence, 30' further, it wouldn't be required. I can't argue with that.
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Joined: Jan 2001
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Electure,
Perhaps someone with access to the history of the NEC could give you the real "why" behind the code article.
The requirement is in 250-32 and in addition, 2 made electrodes will likely be required since this installation must still comply with 250-56.
Few things are harder to put up with than the annoyance of a good example.
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why? i ask that a lot too.
why can i run a 60A single circuit to my shed a mile away to weld with, and not do 2 G-rods?
why can i run a 4-wire 1/4 mile in the same building and not do G-rods?
why should i run a 3-wire 10' to an outbuilding and reground with 2 G-rods in close proximity to the serving buildings G-rods ( read into this, I double-dog dare ya!)
why does a disco rate more 'lighting protection" 30' from a mobiler home , that the home itself?
why is 'voltage gradient' not univerasl?
why?
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Joined: Mar 2001
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Originally posted by sparky: why? i ask that a lot too.
why can i run a 60A single circuit to my shed a mile away to weld with, and not do 2 G-rods?
why can i run a 4-wire 1/4 mile in the same building and not do G-rods?
why should i run a 3-wire 10' to an outbuilding and reground with 2 G-rods in close proximity to the serving buildings G-rods ( read into this, I double-dog dare ya!)
why does a disco rate more 'lighting protection" 30' from a mobiler home , that the home itself?
why is 'voltage gradient' not univerasl?
why?
Reminds me of the philosophy student who got an A+ on the final exam. The only question on the exam was "Why?" His answer---"Why not?"
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it may as well be philsophical, for lack of rationale.....maybe someone would be kind enough to follow thru on Tom's suggestion.
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most inspectors call sheds, detached garages and light poles "seperate structures" Has nothing to do with actual electrical theory.
ed
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nesparky,
It's interesting that you mentioned light poles. I've heard this before, is that true?
Do they require Gr rods at every pole location?
Bill
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The issue of a light pole being a structure has not be specifically addressed in the NEC. The was a code change in the 93 or 96 code in 225-32 to address this issue as far as a disconnecting means at a light pole. It seams that some inspectors, based on calling a light pole a structure, were requiring a disconnect at each pole (structure). 225-32 Exception #3 was added to say that a tower or pole used as a lighting standard can have its disconnect located elsewhere. Maybe we need the same type of exception in 250-32. Don(resqcapt19)
Don(resqcapt19)
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Come to find out, the subject of my original Q has been absolutely dissected (in gargantuan proportions)in other BB's, without a final consensus in any of them. It seems like this really needs to be addressed by the CMP, although I don't really know how they would/could reword it. Any ideas?
[This message has been edited by electure (edited 07-23-2001).]
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elecuture, i would say that looking at what our nieghbors do would be a good start.
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