220.12 calculations for residence

[warrenwaldrop]

I have a 30,000 square foot residence with three three car garages (another 15,000 square feet). The garage square footage is not included in the 30,000 square foot.
The garages are going to have A/C, receptacles, lighting and other electrical equipment. I am trying to verify whether I have to calculate the square footage for the garages at 3 watts a square foot as required in 220.12/Table 220.12 since the garages are going to be air conditioned. The last sentence of the Code Section (220.12) says "For dwelling units, the calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use".

I had planned to calculate the square footage of the garages at 3 watts a square foot and add the other electrical equipment (compressor, welder, etc) at 100 percent or as otherwise allowed by the NEC.

My question is since the last sentence of NEC Article 220.12 states that garages are not required to be included in the general lighting calculations, can I just calculate the loads for each receptacle at 180 volt amperes, lighting at 125% and the other equipment as required by the applicable NEC Article to come up with my service and feeder sizes?

 

[LarryFine]

Warren, garages that big will obviously contain more than just garage space, so the watt/area calc won't be that large a figure compared to the other loads.

In my opinion, the lighting won't be the deciding factor between whatever choices you end up facing for equipment selection. Better too much than too little.

I'd stick with the 3w/sq.ft for now, and only worry about it if it makes the difference between, say, a 200a service and a 300a service for each garage building.