Power transformer grounding

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Isaiah

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Location
Baton Rouge
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Electrical Inspector
This 3MVA delta wye power transformer contains a nema two hole ground pad inside the secondary air terminal Chamber. Construction says this internal pad is part of the transformer casing and therefore is continuous to the two external pads that are grounded to the grid. They contend because of this a separate GEC from the internal pad to the grounding electrode system is not required
The internal pad appears to be bolted to the sheet metal of the air terminal chamber which then connects to the XFMR frame.
Is this an acceptable means of earthing the GEC?


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If the two sets of terminals are only connected by the case of the transformer, I would say not code.

You cannot use the case to run the grounded conductor to the GEC.

Jmnsho.
 
petersonra said:
If the two sets of terminals are only connected by the case of the transformer, I would say not code.

You cannot use the case to run the grounded conductor to the GEC.

Jmnsho.
Click to expand...

I think you’re right about this


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petersonra said:
If the two sets of terminals are only connected by the case of the transformer, I would say not code.

You cannot use the case to run the grounded conductor to the GEC.

Jmnsho.
Click to expand...

Peterson, Do you remember which section in the NEC states if the XFMR is located outdoors and the switchgear is located indoors, the GEC must be grounded at the source, i e XFMR?


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Isaiah said:
Peterson, Do you remember which section in the NEC states if the XFMR is located outdoors and the switchgear is located indoors, the GEC must be grounded at the source, i e XFMR?


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I don't believe it actually says that anywhere
 
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