secondary conductor

[wexley]

what is the minimum size 75 C transformer secondary conductor, not over 3m long for a 480 volt primary to 208 volt secondary transformer supplied by a 200 ampere primary overcurrent device? i am having trouble with the calculation, i do not understand 240.22 help please

 

[billsnuff]

240.22 grounded conductor????

240.22 grounded conductor????

what is the calculated load?

single or three phase?

 

[wexley]

it does not give me that info, i have posted the question as written

 

[augie47]

I would say #8 based on 240.21(C)(2)-{4} ('08 Code)

but I wouldn't take that answer to the bank


200 x 480/208 =461/10 = 46

 

[don_resqcapt19]

Gus,
With the information given, I believe you have the correct answer, but you do have to make the assumption that the load is 46 amps or less.

 

[augie47]

Don, I was going on his question of minimum, but yes, I agree that answer would definitely be load dependant. In the real world, I have failed to ever question minimum as most installations have "load" as the determining factor, as you kmow.
Truthfully, had he not asked, I would have never thought "minimum". Bad for an inspector, but true.