ECN Forum Forums Code Related Discussion NEC & other Code issues What's the difference?

George
240.21(C) or if Supervised Industrial Installation 240.92 (B) . for secondary protection of conductors.
I'd say if you meet rules no protection required at the transformer.
If you do put protection on secondary of the Transformer.
Then I;d say Neutral & Ground would seperate after that to building disconnect switch so EGC would be required & sized by 250.122. (4000Amp = 500KCMIL)in each conduit.

If you do NOT put protection at the transformer location , use PVC & comply with 250.32(B)2.
I;d say no EGC required from transformer just bond at Panel at the Building location.
As far as Grounding or Bonding .I take it your taking about at the XO of transformer. That Does require bonding either way. 250.30 (A).
I take it if you run a EGC to Transfer switch , its a 4 pole right. Otherwise Neutrals bonded both ends ??
I'd say if meets exception of 250.32(B)2 .
Run just Phase condutors & neutral from transformer to Transfer Switch. No protection at transformer.
Then you can use a 3 or 4 pole transfer switch yer choice.
Then at building Treat just like a service as far as grounding requirements.
If 4 pole switch used , Grounding required at Both Generator & M.D.P. if 3 pole just at MDP.(Main Distrubtion Panel)
Seems like in 2008 Ya gotta run the EGC per 250.32(B)unless existing building & meets (1)(2)(3).
If thats true Transfer switch would then HAVE to be 4 pole .
Thats the way I see Open Opinions.
YoopersUp
Is this 120/208 or 277/480??

Note
I have Never seen EGC run from Transformer secondary lugs to ist disconnect outside with that size service.