Feeder to Detached Shop/Barn

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A.Adams

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Location
Tennessee
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Electrician
A friend of a family member pulled a home owners permit to get power to a shop on his property. He decided to get a whole new 200 amp service for this shop rather than pulling from his residence. He has a meter base and main panel mounted to a stand alone structure. His main panel has feed through lugs to feeders that go to a panel in his shop. He used 2/0 CU for this feeder. If it was a dwelling he'd be fine but the inspector failed him for not running 3/0 CU.

He called me looking for some help. I know that if it was a dwelling he'd be fine - 83% according to 310.15 (B)(7). I've looked to see if there is any exceptions for a residential garage, a barn, or a shop when it's not coming from the actual dwelling. I've not found anything but I figured I'd check here with the collective wisdom before I tell him to down size his main breaker or pull new feeders.

Thanks All.
 
The 83% rule only applies to dwelling units as you pointed out. Yep, down size the breaker. That 2/0 Cu must of been expensive.
 
If he had used 4/0 aluminum he could have used the next size up rule for a 200A breaker. This seems to be another example of DIY costing more than getting someone who knew what they were doing.

I would have used 230.40 exception #3.
 
I recommended the HO down size his main breaker and that he should call the inspector and let him know that that was his plan.

When the HO called the inspector, the inspector said that he said that he was thinking about what he would want someone to do for him in the same situation. The inspector is making an exception and will put a note in the file that it’s a hobby shop, not a commercial shop.

Good job inspector in looking past the letter of the law and taking into account the intent of the rule!
 
electrofelon said:
If he had used 4/0 aluminum he could have used the next size up rule for a 200A breaker. This seems to be another example of DIY costing more than getting someone who knew what they were doing.

I would have used 230.40 exception #3.
Click to expand...

Plus the lower cost for aluminum over copper.
 
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