bonding and grounding

[EEuno]

I have an existing building and a new building. The new building is to be constructed immediately next to the existing with a fire separation wall between them. They are to be two (2) separate bldgs. The existing bldg is concrete block and steel and new bldg is all steel construction. Each has a separate service at 208/3. The services are 400+ feet apart. Each bldg has a separate water service and grounding electrode system. Is it best to tie the steel structure of the existing and new bldg together? Is it necessary to tie the water mains and grounding electrode systems together or will the steel structure tie suffice?

 

[7anoter4]

According NEC
250.58 Common Grounding Electrode. Where an ac system
is connected to a grounding electrode in or at a building
or structure, the same electrode shall be used to ground
conductor enclosures and equipment in or on that building
or structure. Where separate services, feeders, or branch
circuits supply a building and are required to be connected
to a grounding electrode(s), the same grounding electrode(
s) shall be used.Two or more grounding electrodes that are bonded together
shall be considered as a single grounding electrode
system in this sense.

I think you have to bond together the foundation grounding of both buildings. The water pipe shall be connected to the grounding electrode in both buildings.

 

[waross]

That article applies to two or more services to a single building. The code does not require adjacent buildings to have the grounds connected, and there may be legal issues if you make a connection to a ground grid that you do not own.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[EEuno]

These are separate buildings but with one owner on one tract of land.

My question is per the NEC is tieing the steel structure of the two buildings together enough for the grounding electrode systems to be " effectively bonded together" and " considered as a single grounding electrode system in this sense." ( NEC 250.58)

 

[waross]

Time for a call to the local AHJ. He is the one who will make the final ruling.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[7anoter4]

In my opinion, if one will follow NEC 250.8 Connection of Grounding and Bonding Equipment. (A) Permitted Methods. it will be enough

 

[mosesnbklyn]

Each service is required to have a separately derived ground electrode per NEC250. DO NOT CONNECT THE GROUND SYSTEMS! The utility transformer neutral/star point is the common grounding point, by adding parallel paths to ground you could create circulating currents.

M. Nissen,P.E.
Senior Electrical Engineer
Waldron Engineering & Construction