Interpretation of 702.5(2)(a)

[aelectricalman]

Full Load. Can and will a load calculation of a residence suffice for the satisfaction of this code? Or does it mean, find the utility bills for the last 12 months? I feel like the first option will suffice. Just a debate around the office, and I think it would be a good clarification to all.

Thanks,

 

[Smart $]

Full Load. Can and will a load calculation of a residence suffice for the satisfaction of this code? Or does it mean, find the utility bills for the last 12 months? I feel like the first option will suffice. Just a debate around the office, and I think it would be a good clarification to all.

Thanks,

I agree, the first [question] option.

Utility bills, unless they furnish demand data (unlikely, especially for a residence), do not meet the NEC criteria for determination of connected load. At best, you could only determine your average usage amount from your bill. Furthermore, if load shedding was implemented, there is no way that can be determined from month-usage billing.

 

[360Youth]

Doesn't it say that it must be sized according to Art 220 calculations?

 

[360Youth]

Doesn't it say that it must be sized according to Art 220 calculations?

Sorry, went back and reread the "or by otther approved methods." One of the more wide open statements in code. :roll: Some jurisdictions require that information with the permit, but not too often.

 

[RICK NAPIER]

220.87 would require you to take 125% of the demand load using the utility demands over a year. There is also an exception on how to do it in 30 days.

 

[cowboyjwc]

You can use an optional method for an existing residence. I'll take the utility bills for commercial projects.

What seems strange is that you calc out the new house and it will call for a 200 amp service, then you do the alternitive method and you probaly will only come up with about a 60 or 80 amps. Maybe a little more.