Transformer grounding

[reyamkram]

From what size kva Transformer you do not have to ground to a grounding electrode system? Can you just use the system grounding electrode conductor ? Where would I find it in the NEC article 250 what?

Thank you for any and all information

 

[infinity]

1KVa and less do not require connection to the GES.

250.30(A)
Exception No. 3: A grounding electrode conductor shall not be required for a system that supplies a Class 1, Class 2, or Class 3 circuit and is
derived from a transformer rated not more than 1000 volt-amperes, provided the grounded conductor is bonded to the transformer frame or
enclosure by a jumper sized in accordance with 250.30(A)(1), Exception No. 3, and the transformer frame or enclosure is grounded by one
of the means specified in 250.134.

 

[jaggedben]

1KVa and less do not require connection to the GES.

Now hold on, don't miss the important details in that exception...

250.30(A)
Exception No. 3: A grounding electrode conductor shall not be required for a system that supplies a Class 1, Class 2, or Class 3 circuit and is
derived from a transformer rated not more than 1000 volt-amperes, provided the grounded conductor is bonded to the transformer frame or
enclosure by a jumper sized in accordance with 250.30(A)(1), Exception No. 3, and the transformer frame or enclosure is grounded by one
of the means specified in 250.134.

Generally line power transformers need a connection to the GES.

 

[reyamkram]

Thank you very much again I appreciate it

 

[infinity]

Generally line power transformers need a connection to the GES.

That's correct, it's right there in the code section I posted.