Grounding a transformer

[jeff1166]

I have a 277/480 volt 800-amp main distribution panel. I am feeding a 75 KVA transformer in another part of the building. The transformer will feed a 120/208 volt 200-amp main breaker panel.Within 5' of the transformer. My feed from MDP is ran under slab.Is it necessary to pull a ground wire from MDP to the transformer? Ground the transformer to the steel and pull a ground wire to the 120/208 panel?

 

[websparky]

Re: Grounding a transformer

YES.

NEC 2002 250.4 General Requirements for Grounding and Bonding.

 

[brian john]

Re: Grounding a transformer

check this link

http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=001421

 

[bob]

Re: Grounding a transformer

250.4A requires an equipment grounding conductor sized per 250.122 and a grounding electrode conductor per 250.66.

 

[gwz2]

Re: Grounding a transformer

What type of raceway system for the 480V circuits ?

Metal raceways, except for Flex are EGC's.

250.134(B).


The secondary side must be grounded / bonded per 250.30(A).