Commercial Service Calculations
The calculation for a commercial building service has to be the easiest one
to make. Typically all the connected load is added together. Then this va number
is divided by the service voltage and 1.732 if it is a three phase service.
There are always little glitches to be concerned about.
First, restaurants have a reduction factor for kitchen equipment. And there
is even a separate calculation rule set for a remodel of a restaurant. Also keep
in mind that for a restaurant, and only a restaurant, the heat and air
conditioner load BOTH are included in the service calculation.
Also, in office buildings there is a reduction in va permitted for
receptacle loads over 10kVA. See the table for that percentage.
Other rules for specific occupancies can be obtained from NEC220 as needed.
Here are some practice problems for various occupancies:
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