Installing power to an outbuilding.


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Old 03-05-15, 11:51 AM
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Installing power to an outbuilding.

If all goes well, I should have a pole barn, by the end of the summer. The building will be roughly 200 feet from the back of the house. This puts the barn about 230 feet or so from the main panel. When the house was wired, all of the branch circuits were run through the top on the panel, with the feeder coming in through the back, leaving the bottom free and clear. The panel is a 30 space 40 circuit panel. There are 27 spaces being used now. My thought, was to put a 125 amp 2 pole breaker in the main panel, and run it to a sub panel mounted just below the main panel. Then, a 100 amp panel in the sub, with the barn feeder out the back through the wall and an LB, then underground. The voltage drop calculator shows that 250 feet of 2/0 aluminum, would have a drop of about 3.3%. Another question is that the neutral bar in the main panel will except 1/0 at the most. Can I run a 1/0 neutral for the 2 feet or so between the 2 panels? Ive included a picture. Thanks. John.Name:  IMG_3985.jpg
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Old 03-05-15, 12:31 PM
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Why the extra 125A panel below the main? Just run the 100A pole barn feeder directly out of the main panel. If the neutral conductor doesn't fit in the panel bar you can buy and add-on lug kit which will accept that size.
 
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Old 03-05-15, 12:33 PM
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Agreed, no need to add the sub panel.

Have you done a load calculation to see if the service can support the additional load?
 
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Old 03-05-15, 12:54 PM
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I thought about that also. as far as the lug kit goes, every space on the neutral bar is used. I would have to use up a space just for the kit. Can I double up a neutral or ground in order to make a space for the kit? Also, the load calc shows that with everything drawing power (not including the out building) the draw is 105 amps. But I believe this would be if everything is on at the same time. Though not sure.
 
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Old 03-05-15, 12:57 PM
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Add a ground bar and move some grounds to make room for the neutrals.
 
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Old 03-05-15, 01:24 PM
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That's a great solution pcboss. Thank you. Only question is, you can see the mounting holes for additional grounding bars. Can I pig tail the grounds, since the wont reach the new ground bar? And if so, can I use butt connectors to keep it clean? Thank you.
 
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Old 03-05-15, 01:30 PM
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Yes you can extend the grounds with wirenuts or crimps.
 
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Old 03-05-15, 03:26 PM
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You also can put two grounds in a hole.
 
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Old 03-05-15, 04:46 PM
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Thanks guys..............
 
 

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