Electric heat feeder calculation

[bwyllie]

When calculating loads for a feeder Art 220.51 states to calculate the fixed electrical heating load at 100%. Art 424.3 states electric heat to be considered a continuous load for branch circuit sizing. In the commentary following 424.3 it also states the the revision for electric heat as a continuous load also applies to the service and feeder calculations.

By code, would I consider the feeder for 100% and branch circuits at 125%?

Comments/suggestions. The 125% would actually be the difference between a 1000A feeder and a 1200A feeder thru an existing building.

Thanks

 

[haskindm]

Follow article 424 for the branch circuits.
Follow article 220 for the feeders and service.
If this is a dwelling, you may also want to look at the optional calculation which allows you to derate multiple heating units.
Commentary (I assume from the handbook) is just the writer's opinion, not official interpretation. I do not see how this could be interpreted as requiring the service calculation to be at 125% when article 220 clearly states it to be 100%.