# Load Calc. for Old Single Family Dwellings



## Reseman (Dec 27, 2007)

Can anyone tell me the best way/formula to use when doing a load calc. on a old house(40+). The customer wants to add a refrigerated air unit to their home. The house is 2000 Sq. Ft with only the Dryer being on a electric circuit. The Water Heater and Stove are gas. The Main Panel is rated at 100 Amps and was installed when they extended the Sq. Footage of their home.
Basically, I want to know what is the biggest refrigerated unit I can install without providing them with a new service upgrade?

Thanks in advance,

Reseman:thumbup:


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## 480sparky (Sep 20, 2007)

The age of the house has no bearing on a load calculation.


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## randomkiller (Sep 28, 2007)

Reseman said:


> Can anyone tell me the best way/formula to use when doing a load calc. on a old house(40+). The customer wants to add a refrigerated air unit to their home. The house is 2000 Sq. Ft with only the Dryer being on a electric circuit. The Water Heater and Stove are gas. The Main Panel is rated at 100 Amps and was installed when they extended the Sq. Footage of their home.
> Basically, I want to know what is the biggest refrigerated unit I can install without providing them with a new service upgrade?
> 
> Thanks in advance,
> ...


 
Exactly what is your electrical trade?


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## Roger123 (Sep 23, 2007)

Reseman said:


> Can anyone tell me the best way/formula to use when doing a load calc. on a old house(40+).
> 
> Reseman:thumbup:


My suggestion is to use Article 220, Branch-circuit, feeder, and service calculations. Also, see 220.16(A)(2). Basically, treat the house as being new.


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## Reseman (Dec 27, 2007)

Roger123 said:


> My suggestion is to use Article 220, Branch-circuit, feeder, and service calculations. Also, see 220.16(A)(2). Basically, treat the house as being new.


So what do you guys do....Do you count all the existing fixtures, outlets, appliances, etc. or do you guys just calculate it as a new house?


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## JohnJ0906 (Jan 22, 2007)

Reseman said:


> So what do you guys do....Do you count all the existing fixtures, outlets, appliances, etc. or do you guys just calculate it as a new house?


You can do a standard 220 calculation, or use 220.83


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