Where to bond?

[Rory Russell]

I am installing a 1200 amp 277/480 GFP/MB service disconnect in a new school.

This will feed a 1200 amp MDP in the same room.

The electrical engineer is asking that all grounding and bonding be in the MDP.

Is this correct?

Thanks in advance.


Rory

 

[roger]

From your description it is not correct, the GEC connection is required to be done at or ahead of the service disconnect, see 250.24 (A) and (B).

Roger

 

[Rory Russell]

From your description it is not correct, the GEC connection is required to be done at or ahead of the service disconnect, see 250.24 (A) and (B).

Roger

Thanks for the quick reply. I'm just getting started on this project and came from out of state and wanted to double check if I was missing an exception.

 

[sellakc@gmail.com]

250.24 is pretty clear - 250.24(A)(1) mentions that the GEC shall be made at the service disconnecting means, with (2) adding an additional grounding connection outside the building IF supplied by a transformer (unless impedance grounding is being used).

I'm confused why an EE would want all grounding and bonding to occur in what is effectively a subpanel, unless he is referring to all other system tie-ins, which could go on an grounding bar in the MDP I suppose.

 

[Rory Russell]

250.24 is pretty clear - 250.24(A)(1) mentions that the GEC shall be made at the service disconnecting means, with (2) adding an additional grounding connection outside the building IF supplied by a transformer (unless impedance grounding is being used).

I'm confused why an EE would want all grounding and bonding to occur in what is effectively a subpanel, unless he is referring to all other system tie-ins, which could go on an grounding bar in the MDP I suppose.

Well, it was so obvious I thought it might be a trick.

Sending an RFI tomorrow.

Thanks