Load Calculations for Large Single Family Residence

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Leo1

Member
Location
Los Alamos, NM
Besides the Optional Demand Calculations in the NEC and article 220-60 on non-coincident loads is there further load demand reductions that apply? For example, on large single family residents the service required can exceed 400AMPs even when applying the Optional Demand Calculations, as shown in Annex D. However, there is a low probability that a single family would ever have a daily demand that exceed 150 AMPs.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Welcome to the forum Leo,

There is no additional demand factors that are allowed for service calculations after you have done the optional calculation method. You are pretty much stuck with using what ever you come up with after doing the optional or standard method of calculation.

Chris
 

Leo1

Member
Location
Los Alamos, NM
Chris,

Thank you. Same conclusion I arrived at, but not what a couple architechs and homeowners I work with want to hear.

Leo





Welcome to the forum Leo,

There is no additional demand factors that are allowed for service calculations after you have done the optional calculation method. You are pretty much stuck with using what ever you come up with after doing the optional or standard method of calculation.

Chris
 

cdcengineer

Senior Member
Leo

I have seen very large (24k SF) residences which have very large service demand calcs. Follow the code, because these larger homes are typically not used the way most homes are used. In resort areas, they can see large groups all using the amenities at the same time. Also, simultaneous heating and cooling can occur with interior rooms being cold and demanding heat while sunny exterior rooms may need cooling. Run the numbers, and the calc is the calc. You can't worry about architects and homeowners. It's not your job to paint yourself into a corner.
 

Leo1

Member
Location
Los Alamos, NM
Senior Member,

Thank you very much. Both you and Chris have confirmed my initial position. If the architect and homeowner go eleswhere for their electrical installation and design guidance I know I have exercised due diligence.

Leo
 
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