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Contributor
Contributor

Hello Martin,

I understand your point. We are bombarded by the local building department requests to indicate a demand load individually per each phase. Currently, in Revit, we added the calculated values of each phase electrical load multiplied by the total demand factor. It does not reflect the real situation but helps us during the permit review process with panelboards and switchboards. 

I understand that Revit's panel balancing option gives a great result but it is could be applied during the original design phase only. Later, when construction starts and more loads added, there is no way to re-balance the entire panel. It will involve the major work from the Electrical Contractor to move circuit breakers inside the installed panelboard per new "re-balanced" layout. This also applied to the existing conditions where improvements are being made. Again, re-balancing helps mathematically relocate loads inside the panel to have each phase calculated load values as close as possible. It does not allow to show the impact of the load types in each phase.

The idea is to evaluate the load for each phase in relation to the transformer, feeder conductors or feeder circuit breaker. The electrical load types are not distributed evenly between phases. One phase could have more receptacle loads, another phase could have more lighting or kitchen equipment loads. Evaluating these loads individually for each phase helps prevent circuit breakers, conductors or transformers to be undersized.

Everybody understands that the sum of the phase demand loads will not be equal to the total panel demand load. There is no requirement to have a total panel demand load to be determined based on the sum of the phase demand loads. These are different values. In some way, it reminds me of school math where three pipes filling the basin, but in this case, the panel is a basin.  The amount of water running in each pipe is not equal and we want to make sure that pipe (conductor) and valve (circuit breaker) are properly sized to let the safe amount of water run through. Current Revit calculations for panelboards and switchboards average these three pipes into single pipe value. This works for panel or switchboard "total" calculations but not for each individual phase.

I hope I described the issue. It would be great to see this happening for panels and switchboards calculations.

Please let me know if you have any further questions.