Transformer Ground Size

[mstrlucky74]

How does one calculate the size of the ground wire( where in NEC) from a 75kva transformer to a ground bar? Thanks.

 

[infinity]

It's properly called a Grounding Electrode Conductor. Look at 250.66.

 

[mstrlucky74]

It's properly called a Grounding Electrode Conductor. Look at 250.66.

Ty

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[don_resqcapt19]

The common GEC used for that application must be a minimum of 3/0. 250.30(A)(6)

 

[infinity]

The common GEC used for that application must be a minimum of 3/0. 250.30(A)(6)

Good point I would guess that knowing where mstlucky works it's at least a 500 kcmil.

 

[mstrlucky74]

They are calling for a #2 GEC from xfrmr to ground bar according to transformer schedule. I've seen that size before so not sure about the 3/0 or #500 you guys mention. I tried referencing the code sections you mention but it was a bit confusing and referred me here and there.

 

[infinity]

They are calling for a #2 GEC from xfrmr to ground bar according to transformer schedule. I've seen that size before so not sure about the 3/0 or #500 you guys mention. I tried referencing the code sections you mention but it was a bit confusing and referred me here and there.

Don is referring to the common grounding riser connecting the ground bars together.

 

[mstrlucky74]

Don is referring to the common grounding riser connecting the ground bars together.

Thanks.