Detached Structure - Separately Derived System

Status
Not open for further replies.
W@ttson

W@ttson

Senior Member
Location
USA
Hello,

Looking for some thoughts on the following situation.

Main building has its own Ground Electrode System. A distribution panel sends a feeder to a remote building where it terminates into a local primary disconnect of a step down transformer. The secondary of the transformer terminates into a local lighting panel. This being a remote building it will have its own GES. The neutral will be connected to the ground terminal through its System bonding jumper. The ground terminal will be bonded to a ground electrode through a GEC.

The question is, does the GEC go to the remote buildings GES or the originating location GES?
 
tom baker said:
Remote building.
It’s lighting panel GEC will use the same GES as well as bonding any water or structural metal in the area served
Click to expand...
Thank you.

May I complicate things a bit more?

Suppose this remote building had a separate service to it (and it is allowed per 230.2). The above regarding the feed and transformer are all the same. I assume the GES at the remote building and the bonding wouldn't change correct?
 
spraymax6 said:
Thank you.

May I complicate things a bit more?

Suppose this remote building had a separate service to it (and it is allowed per 230.2). The above regarding the feed and transformer are all the same. I assume the GES at the remote building and the bonding wouldn't change correct?
Click to expand...
So the remote building is supplied by a service and a feeder? Presuming its allowed then you would have one grounding electrode system for that building tied to the service and feeder.
 
tortuga said:
So the remote building is supplied by a service and a feeder? Presuming its allowed then you would have one grounding electrode system for that building tied to the service and feeder.
Click to expand...
Yes, seems like the Ground electrodes back at the other service get side stepped by the new GES at the remote structure.
 
Side stepped?

A grounding electrode system goes with a structure. I can think of no case where you run a GEC (as opposed to an EGC or grounded conductor) from one structure to another. Maybe a bonding jumper, but I do not believe code ever requires this, at least not for normal services or feeders, separately derived or not.
 
jaggedben said:
Side stepped?

A grounding electrode system goes with a structure. I can think of no case where you run a GEC (as opposed to an EGC or grounded conductor) from one structure to another. Maybe a bonding jumper, but I do not believe code ever requires this, at least not for normal services or feeders, separately derived or not.
Click to expand...
I guess what has always been hammered into my conscious was that "all ground electrodes to be bonded together", but if you actually read that section, there is a clarifier "at each building or structure":

250.50 Grounding Electrode System.
All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)⁠(8) shall be instal⁠led and used.


Its just always been weird that there is this requirement for all electrodes to be bonded together, but a detached garage that is 5 feet away from the main building could have its own electrodes that are not required to be directly bonded to the other ground electrodes (not counting the connection through the EGC feeding the garage, referring to actual 250.66 size requirements).
 
The electrodes at different buildings are still bonded together by the EGC. It's a small difference, and they have to draw the line somewhere.
 
Status
Not open for further replies.
Top