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I am planning to build a small pole barn about 150 - 200 feet from the front corner of my house. The problem for getting power to it from the main panel in my house is that it is located on the opposite corner of the house.

I am in the process of finishing my basement and want to run at least a 100 amp line to the front corner of the house that would eventually feed the barn, before I close up the ceiling in the basement.

If I run the proper wire from the main to the front corner thru conduit in the ceiling do I have to have enough wire coiled up to reach the barn or can I put some sort of sub panel or junction box in that corner of the basement that I could eventually attach a wire to and run from there to the barn.

I would like to just have the wire in the house and not a bunch coiled up in the corner waiting to run to the barn.

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    Please revise to clarify your plans. Are you running a feeder for a sub-panel or a simple 20A circuit? (Wisdom suggests the former.)
    – isherwood
    Jan 12, 2021 at 19:52

2 Answers 2

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Yes you can have a box, but it needs to be big enough, which requires a pull box

There is absolutely nothing wrong with having a box, or a conduit body for that matter, between two sections of conduit so that you can run them at two different times. In fact, the box or body provides a pull point, which resets the 360° bend limit on conduit runs. This is often why you'll see an "in-line" conduit body (C-body) or box at a convenient place in a conduit run in a commercial or industrial environment, even.

However, if you want to use a box for this, you're going to need something chunkier than a standard-issue junction box to provide enough room to feed fat feeder wires through it. Enter the NEMA-rated pull box; these are the bigger brothers of junction boxes, and are available in sizes from 6"x6" up to "wardrobe". Given that a 1.5" conduit is what I'd suggest for the run to the barn, and NEC 314.28(A) says that we need a minimum of eight times 1.5" to accommodate all possible configurations of two 1.5" conduits entering a box, we can safely specify a 12" by 12" by 4" NEMA box, either NEMA 1 with a flush cover for indoor work or NEMA 3R for outdoor work, and have everything fit. Of course, you may be able to use a suitable conduit body, or combination of conduit bodies, instead.

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  • How does the calculation work when it's 1.5" conduit and a 6ga NM coming in, instead of 2 conduits? Jun 21, 2021 at 12:28
  • @DonBoitnott -- please ask that as a new question so that it gets the attention it deserves :) Jun 21, 2021 at 22:21
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Even better don't run ANY wire yet.

Just run the conduit now. Add the wire later, once you figure out exactly what you need. Just make sure the conduit is big enough. You'll need 3 wires if you use metal conduit (hot/hot/neutral), 4 wires (hot/hot/neutral/ground) if you use PVC. There is some downsizing permitted for ground and possibly neutral. If you go with 1" EMT then you are OK for 3 x 3 AWG copper for 100A. If you go with 1-1/4" EMT then you could use 3 x 1 AWG aluminum for 100A.

As far the actual junction box question: You can certainly have junction boxes in between sections of conduit, and switch between wire types. You can also have (but probably doesn't make sense here) cable inside without conduit and transition to wires inside conduit for the outside run, or conduit inside with wires and transition to direct-bury for the outside.

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    Even better, run two conduits, one for power and one for data/phone cabling. Wireless won't be very good after going 200 foot through two exterior walls.
    – Criggie
    Jan 13, 2021 at 4:02

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