When adding a grounding electrode to reach <25? when using a rod, is it permissible to for example, install a second acorn type clamp on the first rod and then run a piece of #6 copper to the second rod located at least 6 feet away from the first rod? The alternative would be to use only one clamp on the first rod and run through the clamp (uncut) to the second rod.
The GEC is the conductor from the Service Neutral to the Ground Electrode System (GES). The GES consists of all the various electrodes which are bonded together. At any one electrode is where the GEC stops. Past this, they are electrode bonding conductors and I don't see any splicing prohibitions on those.
The only thing you have to watch is when different size bonding wires are used. Lets say you have a #4 to a water pipe and then a #6 from there to two rods. You can't run a #4 GEC from the service to the rod because the bonding wire to the pipe is too small. Running a #4 GEC to the water pipe would be OK. Running a #4 GEC to the first rod would be OK as long as a #4 connects the first rod to the pipe. Even if there was a #6 from the first rod to the second this would still be OK.
George: The issue around here was that second #6 was put under the acorn. It is listed for a single conductor only.
Mark: I have never came accross an installation, as you described. It reads like you are running a #4 from the panel to the water pipe, and then a #6 to the ground rods???? I have never seen that, now I'll have to go get the bible!! WHAT DO YOU GUYS THINK??
I have had to do something similar several times. Since we are locally required to enclose the GEC in pipe, and the pipe/ ground rod connector does not allow for the wire to continue elsewhere, it is necessary to use an additional pipe/rod clamp, and run a separate pipe, with a separate wire, to the next ground rod.
The issue around here was that second #6 was put under the acorn. It is listed for a single conductor only.
Simply put 2 acorns on the first ground rod and you are good to go.
250.62(F) is a powerful section that it seems like few people come to grips with. The handbook has a picture that clearly shows the ramifications of it.
To Electrode(s). A grounding electrode conductor shall be permitted to be run to any convenient grounding electode available in the grounding electrode system or to one or more grounding electrodes individually.
This allows both installations that George asks for, provided you use two connectors for the seperated GEC.
A little tip that this section allows is great for a large building. Say you have your switchgear near a building steel column. However your cold water is 500' across the warehouse which happens to be next to another building steel column. Simply bond your switch gear to the first column and bond the 2nd column to the cold water. Thus saving 500' of GEC.
One catch, engineers will often exceed NEC requirements and require seperate conductors. But, that is not required per the NEC.
Re: Additional Ground Rod#95544 09/21/0505:55 AM09/21/0505:55 AM
I have never came accross an installation, as you described. It reads like you are running a #4 from the panel to the water pipe, and then a #6 to the ground rods???? I have never seen that, now I'll have to go get the bible!! WHAT DO YOU GUYS THINK??
I think it is fine.
I have gone from a large service to building steel then 200' - 250' across the building I jumped from building steel to water service saving the long run of 3/0 between the water line and the service.
Here is a Handbook image that shows some possibilities.
Bob Badger Construction & Maintenance Electrician Massachusetts
Re: Additional Ground Rod#95545 09/21/0511:47 AM09/21/0511:47 AM