I am seeing many conflicting installations and am looking for some clarification. For years it has been standard practice here that if you were grounding 3 100 amp panels for a 3 family home served by a 200 amp service (4/0 AL conductors) you would run #4 CU from one panel to the next and then a run to the water main. Is this a violation of 250.64 or am I missing something. What about in the case of a 400 amp service with 2 200 amp panels and going with #2 CU from one panel to the next and then to the water main. This has never been tagged by inspectors but I am questioning this practice.
250.64
- Thread starter moresi
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JohnJ0906
Senior Member
- Location
- Baltimore, MD
I think that is a violation of 250.64(D)(1)
It states the common GEC will remain without a splice or joint.
I was taught that you couldn't use the panel ground/neutral bar to splice the GEC, it had to be tapped outside the panel
I suppose it could be run unbroken through the neutral bar, then out to the second panel, but that would be a pain.
It states the common GEC will remain without a splice or joint.
I was taught that you couldn't use the panel ground/neutral bar to splice the GEC, it had to be tapped outside the panel
I suppose it could be run unbroken through the neutral bar, then out to the second panel, but that would be a pain.
- Location
- Massachusetts
You can make the grounding electrode system up out of any number of electrodes and individual bonding jumpers between those electrodes.
The GEC has to be continuous from the panel to any point on the grounding electrode system.
The GEC has to be continuous from the panel to any point on the grounding electrode system.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You could just tap off with split bolts to both panels. I don't see how this is any different electrically from what you've described. Here's an example from the NECH:
Taking all your comments into consideration and after thinking about this situation more I found myself going back to the code and questioning if perhaps what I am describing is actually what is allowed under 250.64(D)(2)
I am running a grounding electrode conductor from one panel to the Grounding electrode - no breaks / continuous, and sized accordingly, and am then running another grounding electrode conductor from a second service panel to the first where it is tied together with the grounding electrode system via a listed connection. Perhaps I am reading too much into both 250.64(D)(2) and 250.64(D)(3) but to me it appears that I am meeting all these requirements. Supply side of service, accessible enclosure, listed busbars tied together, etc.
I am running a grounding electrode conductor from one panel to the Grounding electrode - no breaks / continuous, and sized accordingly, and am then running another grounding electrode conductor from a second service panel to the first where it is tied together with the grounding electrode system via a listed connection. Perhaps I am reading too much into both 250.64(D)(2) and 250.64(D)(3) but to me it appears that I am meeting all these requirements. Supply side of service, accessible enclosure, listed busbars tied together, etc.
How are the ungrounded conductors getting to each 100A panel? If you used a gutter, it would be easiest to just run a #4 from the neutral in the gutter to the ground electrode system. Then you're done. There is no requirement to have a GEC from each panel as long as the neutral to the panel is sized per 250.66 for the ungrounded conductors feeding that panel. On the line side of a service disconnect, the neutral is permitted to provide the grounding path.
I've seen people criss cross #4's between 200A panels in a 400A service. It just seems so much simpler to use a 1/0 GEC from one panel or a common point upstream to the ground electrode system.
I've seen people criss cross #4's between 200A panels in a 400A service. It just seems so much simpler to use a 1/0 GEC from one panel or a common point upstream to the ground electrode system.
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