Transformer secondary tap

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NOV

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IDC Electrical Review Engineer
If I have a 75KVA transformer feeding a 200A panelboard 100feet away, can I tap those feeder conductors in the middle of the run and feed another 200A panelboard without installing an overcurrent device between the transformer and the tap?
 

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No.
You can run a 2nd set of conductors from the transformer to the 2nd panel provided the transformer primary over-current protection does not exceepd 125% of the primary current.

{Depending on the specific details (ie: delta, wye, insiide, outside, etc) yoru 1st secondary might not meet Code}
 
Sorry had to run out yesterday. Transformer is 3 phase, 480 x 120/208, indoor. No OCPD between transformer and 200A panel. I thought it had to go back to the transformer but I'm having a hard time finding the article in 240.21 that applies to this scenario.
Thanks for the help!
 
Start at 240.21(C(1)). Note that since your transformer is NOT a 2 wire-2 wire or delta-delta, the secondary conductors are NOT considered to be protected by the transformer primary device and require protection at their ampacity and they must meet the rules in 240.21(C) as to length and termination (Generally not over 25ft and terminated ina single device),.
 
FYI, this is a school job, but I don't see where that makes a difference.
It seems that since this installation is not in a high bay, and it exceeds 25 feet , I would say it is not acceptable. Would you agree?
 
NOV said:
FYI, this is a school job, but I don't see where that makes a difference.
It seems that since this installation is not in a high bay, and it exceeds 25 feet , I would say it is not acceptable. Would you agree?
Click to expand...
I agree, as designed it is not NEC compliant.
 
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