12470 Delta to 480/277 Wye Question ASAP please

[zeilzabob]

I have a customer who owns their own primary. The incoming service is 12470 which is terminated at a 15kv switch/meter/distribution section. From there one of the switches feeds a 12470 to 480/277 outdoor transformer. Which in turn feeds the 3000 amp 480/277 main disconnect inside the building. Does the XO on the secondary of this transformer have to be bonded? I cant find the article.

 

[raider1]

Check out 250.20 for when an electrical system must be grounded. If you have a 480/277 volt system in which the neutral conductor is used as a circuit conductor you must ground the secondary of the transformer. Also check out 250.30 for the requirements for grounding of separately derived systems.

Chris

 

[iceworm]

I have a customer who owns their own primary. The incoming service is 12470 which is terminated at a 15kv switch/meter/distribution section. From there one of the switches feeds a 12470 to 480/277 outdoor transformer. Which in turn feeds the 3000 amp 480/277 main disconnect inside the building. Does the XO on the secondary of this transformer have to be bonded? I cant find the article.

Get out your engineer's hat. The NEC doesn't specify. First you have to decide what you want to do with it. Then the code (250.20) has some clues if it needs to be grounded.

Then again, maybe you don't want grounded or un-grounded. Maybe you want HRG

ice