EG to utility transformer

[Nom Deplume]

Is there an NEC article that addresses an equipment grounding conductor to the utility transformer?

I have a building that has a 600 amp 3phase 480/277v service and has an equipment grounding conductor from the utility transformer that is going through the grounding bushings and is landed on the neutral bar. The connection between the neutral and the equipment is just the jumper strap.



I have the same issue on the load side of this equipment. The equipment ground conductor is connected to the neutral bar and is looped through the ground bushings to an MCC.

Should the EGC be run to the utility transformer?
Is there a code article for this or is this the utility standard? I have never run an EGC to a utility transformer. I have seen engineers do this on the drawings, but we have never installed it this way.

We are supose to correct the grounding on this job for a VFD installation.

 

[petersonra]

why are there two green taped wires?

 

[Nom Deplume]

The two green wires are the EG that is in the two conduits from the utility transformer.
They loop through the top grounding bushings in the other photo.

 

[david]

When this is done you are basically paralleling the grounded conductor from the utility to the service disconnect.

The equipment ground conductors are connected on both ends the same place as the service grounded conductor.

I would consider this to be objectionable current and a would also look at this as paralleling conductors of different sizes

 

[infinity]

There should be no EGC's run with the service entrance conductors.

 

[augie47]

There should be no EGC's run with the service entrance conductors.

What Rob says !

On occasion an engineer will request such locally but there is no need and installing them often results in a violation as noted in the earlier post.

 

[Nom Deplume]

There should be no EGC's run with the service entrance conductors.

What Rob says !

On occasion an engineer will request such locally but there is no need and installing them often results in a violation as noted in the earlier post.

I know it's not done, but is it an NEC violation?
I've seen this on drawings, but we never installed it that way.
We never run an equipment ground with the service conductors.

 

[Smart $]

...Is there a code article for this or is this the utility standard? ...

See 250.6, and most notably (A) and (B) therein. The NEC requires installation and arrangement to prevent objectionable current. Grounded conductor current through a grounding conductor, under nominal operating conditions, is objectionable current (I have to say IMO, as there is no technical definition for objectionable current).

 

[augie47]

As noted in Post 4 by david, if the conductors are basically connected together at both ends and not identical, you have a violation of 300.3(A)(1)

 

[kwired]

The only way for it to serve any effective purpose would be to not have a bonding jumper from neutral to ground at the service disconnect and of course having the EGC separated from the neutral bus also, otherwise as already mentioned it creates parallel paths for the neutral, and those paths are not identical making improper "paralleled conductors".