Main building grounding system

[anbm]

There is a main service electrical room inside the existing building will all grounding system were already established. Now the owner want to convert another room (also inside the building) to become main service electrical room, add new main gear in this room and re-feed old main electroical room from the new room.
The old electrical room now become a branch electrical room.

Since the foundation is existing, the building is existing (built in 1975), how are we going to establish new grrounding system for new main electrical room? We can't install anything underground right? (the existing grounding system for existing main electrical room shall be disconnected).

 

[raider1]

You will need to extend the existing grounding electrode conductor from the old service location to the new service location and do the gronding and bonding at the new service location.

Chris

 

[pete m.]

I agree with what Chris has stated and might add a couple other items to be aware of.

1. The neutral/ground bond at the "old service" will have to be removed and the EGC's separated from the grounded conductors.

2. Since you have an existing structure the CEE (concrete encased electrode) would not have to be utilized but any other grounding electrodes present would have to be utilized.

3. Due to this being a new service you would have to make attachments to the electrodes up to todays standards... i.e. water line within the first 5 feet of entrance. As Chris stated previously you may be able to accomplish this simply by tying onto the existing GES but you would need to verify the existing for compliance with the currently adopted edition of the NEC for your area.

Pete