When do we need load calc for a residence?

[mwm1752]

Obvious undersized service is easy to notice once you've done many calculations is the only time I have asked- I only know of 1 code section that may have reason for call out by AHJ & it is kind of far fetched - I think it could apply for services in residential over 400 amps since:

IRC 2015 E3401.3 Not covered. Chapters 34 through 43 do not cover the following:
1. Installations, including associated lighting, under the exclusive control of communications utilities and electric utilities.
2. Services over 400 amperes.

NEC 2017 - 215.5 Diagrams of Feeders. If required by the authority having jurisdiction, a diagram showing feeder details shall be provided prior to the installation of the feeders. Such a diagram shall show the area in square feet of the building or other structure supplied by each feeder, the total calculated load before applying demand factors, the demand factors used, the calculated load after applying demand factors, and the size and type of conductors to be used.

 

[jaggedben]

You live in the land of high electric rates.

Come to places that can have as little as 5 cents per kWH during heating season and you run into electric heat being reasonable to use cost wise, especially a few years back when gas prices were much higher than now.

I did a new home 10-15 years ago that had 60 kW of permantly installed heating units, 5 4500 watt water heaters, two laundry rooms with electric dryers, two baths with in floor electric heat (don't recall watts on those anymore).

Take away all those loads and go with gas heating as much as possible, load calc may still have gone over 100 amps, but maybe not by much. Take away the AC units and I bet it is less than 100 amps.

Well, I haven't done a load calc yet for a house with 5 water heaters, that's true. :-D