PDU and XFMR secondary conductor protection

[elec_eng]

300KVA, 480-120/208V PDU in a Data Center. (1) 700A input breaker at the primary of xfmr and (6) 225A output breakers at the secondary of the xfrm.

Looks to me it doesn't comply with 240.21(C) and 404.36(B). Are PDUs exempt from NEC because they are UL listed equipment?

 

[ron]

I've brought that up a billion times and the excuse given to me is the UL listing as an assembly. The wire sizes within the assembly is also not regular code compliant.

 

[petersonra]

They are not exempt. They are just not covered by the NEC.

90.7
...
It is the intent of this Code that factory-installed internal
wiring or the construction of equipment need not be
inspected at the time of installation of the equipment, except
to detect alterations or damage, if the equipment has
been listed by a qualified electrical testing laboratory
...

While this part of the code is not generally enforceable, it clear states what the intent of the code is with respect to listed equipment.

 

[elec_eng]

Thanks...I susptected that was the case.