Making connection between MGB in Old Building and MGB in New Building.

M

marcosgue

Senior Member
Location
Tampa
Occupation
Electrician
This's the scenario. Existing building with MDP and main ground bar. The new building is the location of Emergency generator Switchgear room with the own main ground bar and separate about 30' from the existing building. Questions
1. Is necessary to make connection with 3/0awg between the two buildings? Purpose of this connection? Any nec reference to do this
Thanks in advance
 
Asssuming that each separate structure has its own GES they do not need to be connected together.
 
That's my understanding Infinity, but let me more explicit. The existing building have a Main Distribution Panel with their own GES and the new building have a Swithgear Emergency Generator secction with their own GES. This is a hospital with the Normal Power source in the existing building and the Emergency Power source in the new building and the EOR refer that both ground bar have to be joined together to re-establish the grounding electrode system. Any NEC reference behind this argument?
 
The connections between the two buildings will be via the feeder EGCs which will actually be connected to the grounding electrode systems in each building via the main and system bonding jumpers. No additional connection is required.
 
They don't need to be bonded together. They both need to be bonded individually. Follow NEC sec. 250 on what size conductor to bond each.
 
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