Transformer Secondary Protection

[faresos]

I have 150 & 112.5 Kva tansformers feeding panelboards to power 208/120v loads such as receptacles, the transformer and the panelboards are located in the same room but I believe the secondary feeders exceeding 10ft before lands on the main circuit breakers in the panels. The primary and secondary feeders and overcurrent protections devices are sized based on 125% of the FLA of the transformer. Would that be a code violation since it exceeding 10ft without overcurrent protection? I'm reading Art. 240.21 NEC but still I'm not sure. (this project for High School)

Thanks for your help in advance

 

[Volta]

. . . Would that be a code violation since it exceeding 10ft without overcurrent protection? I'm reading Art. 240.21 NEC but still I'm not sure. (this project for High School)

Thanks for your help in advance

Maybe, depending on OCP and conductor sizes. Look at 240.21(C)(6) to see if that will help.

 

[augie47]

I believe you will find your answer in 240.21(C) (1), the last paragraph.

 

[belkymd]

Xfmr Overcurrent Protection

Xfmr Overcurrent Protection

I have 150 KVA delta to wye transformer with a 225A/3P primary breaker. The engineer of record has depicted the transformer feeding two secondary panels. One panel has a 225A main circuit breaker and the other is 400A main lug only. I am questioning whether the MLO panel is acceptable per code. Your thoughts?

 

[raider1]

I have 150 KVA delta to wye transformer with a 225A/3P primary breaker. The engineer of record has depicted the transformer feeding two secondary panels. One panel has a 225A main circuit breaker and the other is 400A main lug only. I am questioning whether the MLO panel is acceptable per code. Your thoughts?

The panelboards overcurrent protection must be located on the secondary side of the transformer. Take a look at 408.36(B) (2008 NEC) or 408.36(D) (2005 NEC).

Chris