Main Swbd sizing

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funseebee

Member
Location
CA
I was looking at a calculation done by somebody else.
The project is a mixed use bldg. with 16-residential units on 2nd & 3rd floors.
First floor has parking spaces, retail space, elevator and lobby.

The residential units were calculated as follows:
ltg/recept = Area of each unit X 3w/sf
Major equipment are range/oven, dishwasher, clothes washer and dryer, fridge, microwave, garbage disposal.
The loads are added with the first 10,000w
Then the remainder X 40%
Plus the heater @65% DF
The total is the connected load in the panel.
The total for the 16-units are added up to size the main for the residential units.

Now, the elevator load, , retail (3w/sf) are added.
The house load (3w/sf).
The loads are added with the first 10,000w
Then the remainder X 40%

The total for all is the size of the main swbd.

Is there something missing here? Or am I just confused? Please advise.

Thanks.
 

bob

Senior Member
Location
Alabama
funseebee said:
IThe total is the connected load in the panel.
The total for the 16-units are added up to size the main for the residential units.
You may not mean what I think your are saying. You do not add up the total
load in each apartment to get the total load for the main. The NEC provides you tables such as 220.42, 220.54, 220.56, 220.55 and others to get the total load for the main switch. Maybe that's what you meant to say.
 
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