Residential pole barn

N

nizak

Senior Member
Inspector is asking for a service load calculation at an existing home that’s getting an addition.
There is a pole barn on the property that is being fed with a 100A 240V feeder.

The building has lighting and 120V receptacles.

No 240V loads .

What kind of a value do you place on it for the calculation?

Thanks
 
That's a tough one. Table 220.42(A) lacks a lot of different building use cases. You could maybe consider it a workshop at 1.7VA per square foot. An inspector shouldn't quibble if you treat it like a dwelling at 3 VA per square foot. Be sure to add any fastened in place items or circuits for specific items to the calc. If all you have is 3 VA/SqFt, that is going to be a rather small feeder.

My pole barn is a workshop and there are dedicated circuits for a lot of things. But I am a one man show, so only so many things can be used at once. That may not fly with some inspectors, but its the reality of the past, current, and planned future use.

How many breakers are in the pole barn panel and are they all 15A or 20A single poles?

If that pole barn is existing for a year, you could try using demand data from the power company if you have it which should cover past usage of everything that has been there. Then use 220.87 to cover all the existing and focus on the new.
 
The whole job is a mess. House is 40 years old and was wired by Uncle Rich.

20 space 200 amp QO panel is the main that is packed full of unnecessary wiring.
Feeding out of that is a
- 100 amp feeder to a sub panel located at the opposite end of the existing structure. #2 Cu.( maybe a 30 amp max load.
- 100 amp feeder to the pole barn. #1 Cu.
- 6/2 NM for AC ( #10 would suffice)
- 10/3 NM for mini split ( #12/2 would suffice)
-10/3 NM for water heater( 10/2 would suffice)
- Couple garage circuits
- Looks like #2 Cu for GEC ( 2 wires)
I need to get a #2 SER cable in it for a new addition,

I learned he was a industrial electrician and it’s obvious.
 
nizak said:
The whole job is a mess. House is 40 years old and was wired by Uncle Rich.

20 space 200 amp QO panel is the main that is packed full of unnecessary wiring.
Feeding out of that is a
- 100 amp feeder to a sub panel located at the opposite end of the existing structure. #2 Cu.( maybe a 30 amp max load.
- 100 amp feeder to the pole barn. #1 Cu.
- 6/2 NM for AC ( #10 would suffice)
- 10/3 NM for mini split ( #12/2 would suffice)
-10/3 NM for water heater( 10/2 would suffice)
- Couple garage circuits
- Looks like #2 Cu for GEC ( 2 wires)
I need to get a #2 SER cable in it for a new addition,

I learned he was a industrial electrician and it’s obvious.
Click to expand...
Hmm, sounds like you are knocking the guy for planning ahead with extra conductors?

Anyway, all I've ever done here is provide the actual loads in a barn. I fail to see how that can fall into some "NEC std" as some barns only have 2 light bulbs. Seems more like they want a reasonable calc for mainly the house to ensure the addition does not push over the edge. I would agree that POCO use will probably serve this need better than any calculator in NEC.

But it's always lovely to find the smallest circuit space box money could buy at the time! Who knows, maybe Ol Rich was handed that turd and told "I got it cheap, can we use this?"
 
fastline said:
Hmm, sounds like you are knocking the guy for planning ahead with extra conductors?

Anyway, all I've ever done here is provide the actual loads in a barn. I fail to see how that can fall into some "NEC std" as some barns only have 2 light bulbs. Seems more like they want a reasonable calc for mainly the house to ensure the addition does not push over the edge. I would agree that POCO use will probably serve this need better than any calculator in NEC.

But it's always lovely to find the smallest circuit space box money could buy at the time! Who knows, maybe Ol Rich was handed that turd and told "I got it cheap, can we use this?"
Click to expand...
I’m fairly certain there was no planning ahead, just simply overkill.
I’m not knocking the industrial guys .

I always remember a saying that my first employer had when it came to overkill.

Swatting flies with a sledgehammer.
 
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