Transformer Grounding

[Gleybe]

Good Afternoon,

I am projecting a substation on the 3rd floor of a building with five delta-star 1250 kVA transformers and I need to ground its neutral to the metal structural frame of the building on the underground

Accordingly with table 250.66, the size of GEC have to be 3/0, is my understanding correct?

Thanks in advance for the help

 

[augie47]

Correct.
(Note the SBJ or SSBJ might be required to be larger)