Residential Calculations

[xformer]

Hello, according to my knowledge 220.57 is now a requirement for dwelling load calculations. Is this correct?

 

[wwhitney]

Hello, according to my knowledge 220.57 is now a requirement for dwelling load calculations. Is this correct?

Only if doing the standard method (Article 220 Part III). When doing the optional method (Part IV) for the service or main feeder, 220.57 doesn't apply. Of course, for feeders supplying a subset of a residence, the optional method is not applicable, so 220.57 would apply.

Cheers, Wayne

 

[jaggedben]

... Of course, for feeders supplying a subset of a residence, the optional method is not applicable, so 220.57 would apply.

Except to the extent that if the upstream service or feeder conductor were sized to 310.12 using the optional method, the feeder for the subset would not have to be larger.