GEC SIZE FOR MULTIPLE SERVICES

[teezer38]

I have 3 seperate 400a 1phase services in a small 8'x6' shed,all fed from the same utility transformer.Can I use 250.66(a) and run a continuous 6cu for the GEC from the 3 breaker disconnects to 2 -8ft. copper ground rods?

 

[augie47]

You can actually run a #6 to from the ground rod to the 1st disconnect & tap off that #6 twice to the other two.
Your "tap" should be outside of the 1st disconnect.
See 250.64(D) & sketch below

 

[teezer38]

That was my plan. Thanks.

 

[electrofelon]

Your "tap" should be outside of the 1st disconnect.

Is that a requirement? I ask because I recently did a service with multiple enclosures and the inspector said the various GEC's connections couldnt be inside the disconnects. I didnt bother looking it up as it was easy to change and I was in a hurry. If I recall I had the rod GEC going into one enclosure and the building steel going into the other enclosure. He wanted a common grounding terminal bar outside of the enclosures.

 

[augie47]

Another poster and I had a recent disagreement on that, but, the way I read 250.64, the "tap" must be outside of the disconencts and the tap "extend to the inside of each disconnecting means" {the quoted text is fro 250.64(D)(1)}