Load calculation for busway

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32Lateralus

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If you have an overhead busway system, something like Starline, that allows for addition of disconnects or other power devices after design and installation, how would load calcs work for this?

If I have a 400A busway, but the equipment on it is only 100A, when running calcs for upstream distribution or service, would it be the 100A or the 400A capacity of the busway that is required to be used? I see NEC 368 covers overcurrent protection ratings which all makes sense, but nothing on load.

I think the ability for a customer to just snap in a unit and add more load is what's concerning me.
 
There is no specific direction in the NEC regarding that condition. We calculate based on the loads we know and can't predict the future.

It is slightly different for things like track lighting (track is similar to busway).
 
ron said:
There is no specific direction in the NEC regarding that condition. We calculate based on the loads we know and can't predict the future.

It is slightly different for things like track lighting (track is similar to busway).
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That's what I had thought, would drive the service size up like crazy to size based on busway capacity.

Yep, track lighting and multioutlet assemblies, things like that are what made me wonder since they have specific requirements for load. Thank you
 
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