Residential Load Calc Worksheet

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Clayco

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I downloaded the residential load calculation worksheet and filled it out for my present residence based on my appliances and HVAC equipment. The worksheet came up with 191 amps and a minimum service size of 200 amps. I wondered if there is any safety factor included the calculation? If so, what percentage is the safety factor?

I'm considering finishing the basement and wonder if the existing 200 amp service is going to be enough, or if I'll need to increase it.
 
Knowing that you are not an electrician;

There are no safety factors added to an NEC 220 worksheet as this type of computation reduces the service ampacity requirements to its minimum. Increasing your service requires more than just changing your service panel board. I suggest that you contact a qualified electrican and maybe an engineer to continue with this project.
 
A load calculation is an estimate of probable load based on what an average occupant might use at any given time. I have seen very few tripped mains (due to overload) in my 30+ years of doing residential service work. There are more than just a few 3000-4000sq ft homes out there doing just fine on a 100amp service. I don't recommend that though. The only way to really know what's happening is to put a recording amp-meter on your service for a month or so during your highest use time which can be found by going through the past years utility bills.
 
There are two different ways to do residential calculations -- the standard method and the optional method. Typically, the optional method comes up with a smaller value and sometime significantly so. You may want to try the optional method if your calculation tool used the standard method.

If you have electric heat, you get killed with the standard method.
 
I realize upgrading the electrical service involves more than the panel board. The house is 2 yrs old and have no apparent electrical issues to date. The electrician that wired the house thought the 200 amp service was adequate. My concern has to do with a 5 ton and 2.5 ton heat pump that is accounting for 30% of the load. I think I'll take Bob's advice and have a meter put on it to see what I have. Thanks for the info.
 
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