Installing Grounding Electrode & GEC (old)

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sparks27

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Portland, Oregon
Guys, Here you go 1961 era, Multifamily dwelling. 400 A Zinsco Service the EGC goes thru 1" ridgid to Bldg. supply water line and is clamped. problem is the supply line is 3" pvc below grade no 10' contact with soil. so.. add a rod sized to service and gec , 250.66 says 1/0 copper. Does this have to be one piece from service, to pipe, to rod, or can I clamp to pipe and go to Rod with Proper Clamp of Course!!
 
Dennis Alwon

Dennis Alwon

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Perhaps this will help. The main GEC must be continuous to the panel. So you may go from panel to water pipe and water pipe to rod but I agree with Bob that a #6 is all that is necessary to the rod.

ry%3D400
 
Dennis Alwon

Dennis Alwon

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sparks27 said:
So the (main) GEC to water pipe is ok. The GEC to the rod is sized to #6? got It. why the change? I thought it had to be sized to 400A.?
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As long as I remember the gec to the rod could be a #6. Often times engineers spec larger but the rod is basically no better than a #6 thus it is worthless running a bigger conductor. The same is true with a CEE (concrete encased electrode) only that never needs to be larger than a #4.
 
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hurk27

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Portage, Indiana NEC: 2008
sparks27 said:
Guys, Here you go 1961 era, Multifamily dwelling. 400 A Zinsco Service the EGC goes thru 1" ridgid to Bldg. supply water line and is clamped. problem is the supply line is 3" pvc below grade no 10' contact with soil. so.. add a rod sized to service and gec , 250.66 says 1/0 copper. Does this have to be one piece from service, to pipe, to rod, or can I clamp to pipe and go to Rod with Proper Clamp of Course!!
Click to expand...


I don't think you can jump off the water line if it is not an electrode, as you stated above highlighted in red. grounding electrode conductor must be continuous, and if the water pipe is not in contact with Earth for 10' or more then it is not an electrode. other wise we could just attach a GEC to any water pipe or hose bib.
 
tom baker

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sparks27 said:
So the (main) GEC to water pipe is ok. The GEC to the rod is sized to #6? got It. why the change? I thought it had to be sized to 400A.?
Click to expand...

The size of the GEC is not based on the OCPD of 400A but the ungrounded conductors. A 20 ampere service with 3/0 copper would require the same size GEC as a 200 ampere service.

This is not a change on the size to a rod, plate or pipe electrode.
Read 250.66(A). There is a difference between section 250.66 and table 250.66
 
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sparks27

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Location
Portland, Oregon
Thanks Tom, I need to go check the conducter size of feeders to service, for the GEC size and use the table 250.66 accordingly. that will give the size of GEC to the rod.
 
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