MLO Panelboard Overcurrent Requirements

[lsubrian83]

I'm working in an industrial environment (refinery) and have the following question:

I have a panelboard, with main circuit breaker included, 225A rated. It is a 42-ckt, 125VDC panelboard. Construction has installed a 2nd panelboard, main lugs only, fed from the bus of the 1st panelboard. A 3rd panelboard has been installed, main lugs only, fed from the bus of the 2nd panelboard. All of these panelboards are identical 125VDC, 42-ckt. They are located in the same building (230kV substation control room). Does the NEC code allow this installation, assuming loads do not exceed 225A? In other words, does the upstream main breaker of the 1st panel qualify as protection for the downstream 2nd/3rd panels? Please provide article numbers from the code with your answer.

Thanks!

 

[rbulsara]

The answer is yes.

As for the code article numbers, you can read the code book as well as anyone else can.





Rafiq Bulsara

http://www.srengineersct.com

 

[waross]

If this is a utility owned installation it may not be under the jurisdiction of the NEC.

But, if the panel is not supplied with full current taps or lugs on the bottom of the bus bars, adding feed through lugs would void the UL listing and the panels would no longer be approved.If the work can be completed with approved hardware it is probably acceptable under the NEC. I doubt that approved hardware is available but I have been wrong before.

In a utility owned sub, the engineer of record may choose to have the lugs added. In the event of a failure, possibly due to poor workmanship, reduced clearances, or other issues, the engineer of record may have to justify his design and decision to deviate from UL listings at an inquiry.


Bill
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"Why not the best?"
Jimmy Carter