Lighting & Recep Load Calcs on Multiple Panels

[hitehm]

Situation: Customer has a (very common in our area) 400A square-D service panel in the attached garage that splits between 2 service disconnects, one 200A mb supplying the local bus and one 200A mb feeding a remote subpanel in the laundry room. The local bus has NO lighting circuits but does have general-purpose receptacle circuits. All the lighting circuits are in the remote subpanel. The back-fed solar breaker lands on the local bus. Inspector wants load calcs done on each panel.

So, the question is for the local panel, how do we separate out the general-purpose receptacle circuits from the lighting circuits for the load calcs if they are both tied to the sq footage? And if not separated, how is it done? It seems overkill and inaccurate to apply the full 3va/sf for a panel with no lighting loads just for the receptacles. BTW, the remote panel has both lighting and receptacle circuits so applying the full 3va/sf seems reasonable in my opinion.

 

[suemarkp]

I don't think the NEC tells us what to do here. You may be able to use the nameplate values of the lighting, or if it is screw shell lights whatever their max rated wattage is per fixture. But inspector could argue those fixtures could be changed. If there is a one receptacle on that lighting branch circuit, that makes it more complicated. Usually, the 3VA/sq ft is a minor contribution to the overall load calc's I do, so I don't see it being a huge deal in most cases if you have to do 3VA for pure lighting too. It is the things like a 10A garbage disposal that rarely runs that get me...