Grounding and Bonding Multiple Buildings with a Single Service

[chuggb]

I have a project (in bid) that has four (4) buildings and a single 800A service. The main distribution panel is located in the exterior of building D.

Building A has two (2) panels from MDB each 200A. This building is CMU and steel support with a 1"C water pipe (copper).
Building B has one (1) panel from MDB also 200A. This building is CMU and steel support with a 1-1/4"C water pipe (copper).
Building C has one (1) panel from MDB at 60A. Building C is CMU and steel support.
Building D has (1) panel from MDB with 100A. This building is CMU with steel decking.

When grounding separate buildings from a single service, 250.32 (A) states, "...shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250." Part III of Article 250 states, "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."

Please correct me if I'm wrong but, this means I would have my grounding electrode (from the same conduit as my current carrying conductors) and this electrode would be connected to each building's; metal underground water pipe, metal in-ground support structure, and concrete-encased electrode.

 

[augie47]

If these are separate buildings each one will have it's own GES.
If they are supplied by a feeder, an EGC would be required from MDB

 

[Perri Redder]

"If these are separate buildings each one will have it's own GES.
If they are supplied by a feeder, an EGC would be required from MDB"

Simple, straight to the point, and 100% correct.
Awhile back you could have gotten away with just a separate GES for each building. Now everything needs to be grounded back to the MDB. Don't be the other guy. New things aren't always better, but our newest code is almost ALWAYS safer.

 

[electrofelon]

Awhile back you could have gotten away with just a separate GES for each building. Now everything needs to be grounded back to the MDB. Don't be the other guy. New things aren't always better, but our newest code is almost ALWAYS safer.

Every building did, and still needs a GES. What used to be allowed (with some conditions like no parallel metal paths between the served and serving buildings) was using a single conductor for both the neutral (grounded) conductor and as the fault clearing path back to the source. To do this the neutral and EGC's were bonded at the served building, like a service.