Ground bus interior building

[hhsting]

I have subpanels in room load side of service disconnect means in building for government agency for transit call WMATA.

Equipment grounding conductor is brought to the subpanels and to AC power equipment that power light and power but in the room their is also ground bar. The ground bar connects to other ground bars which then connect to main service grounding electrode system. The ground bus bar would bond AC power equipment enclosure including the subpanels in the room.

I always thought NEC 2014 Section 250.86 which says equipment connected thru EGC.

Would the ground bus bar that connects AC equipment enclosure in room in addition to EGC above mentioned not in compliance with any NEC 2014 sections?

 

[petersonra]

I don't see any code violations here. The code does not restrict you from having equipment grounding conductors that are separate from the equipment grounding conductors that go with the feeders and branch circuits. The requirement is that you must have an equipment grounding conductor with all feeders and branch circuits not that it can be the only one.

 

[Fred B]

Consider: (not aware of what might apply to your situation other than 1.)
1 All grounding conductors must be bonded back to the main panel where ground/neutral are bonded for EGF protection to occur.

2 If equipment has no neutral, and ground is being used to carry unbalanced loads as was case in many older stove and dryer installations, I would not bond in such way that would potentially energize via grounding conductor other circuits that are terminated away from the protection device location and carried back via a common ground conductor.

3 Also consider that any point that extends or increases the impedance of the fault current path also increases time for a fault to clear.

 

[hhsting]

Consider: (not aware of what might apply to your situation other than 1.)
1 All grounding conductors must be bonded back to the main panel where ground/neutral are bonded for EGF protection to occur.

2 If equipment has no neutral, and ground is being used to carry unbalanced loads as was case in many older stove and dryer installations, I would not bond in such way that would potentially energize via grounding conductor other circuits that are terminated away from the protection device location and carried back via a common ground conductor.

3 Also consider that any point that extends or increases the impedance of the fault current path also increases time for a fault to clear.

In my case ground bus bar is to connect equipment and the ground bus bar connects to other ground bus bar which connect to main service grounding electrode system

And

I have EGC in raceways which bond the main service panelboard neutral/ground bond.

Post #2 says having two of EGC is not violations of NEC 2014

 

[Fred B]

Size of grounding conductor needs to be sized so that all potential fault loads can be carried back to circuit protection and follow restrictions and sizing requirements of 250.122.