Rerouting/Extending an Underground Wire (in PVC conduit)

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Old 08-07-13, 09:21 PM
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Rerouting/Extending an Underground Wire (in PVC conduit)

I need to reroute (extend) an existing 3/4 inch PVC conduit containing a 12-3 UF-B W/G wire that leads to my garage. The previously buried (2 ft) conduit is now exposed at the garage end, and the masons are ready to start their work. The attached picture shows the conduit traversing the gravel base that will be the foundation for a set of steps; the rerouted conduit needs to go down 3 feet to the gravel, go across the gravel, and then come up the side of the garage. So, basically, I need the electrical wire to be about 6 feet longer. I think there are two options:

1) Pull out all of the existing wire from the 3/4 inch PVC conduit, replacing it with a longer wire, while rerouting the conduit. This would require pulling the old (and new) 12-3 UF-B W/G wire through about 75 feet of that 3/4 inch PVC conduit. Is that doable for that length of wire? If so, that would be a cleaner result than Option #2 (although it would cost about $100 in new wire).

2) The other option would be to add a junction box to the left or right of that gravel area. I understand that a junction box like this needs to be at (or above) ground level (i.e., can't be buried). Unfortunately, it looks like the end of the redirected wire won't reach the garage wall, so the junction will need to pop out of the ground. If I go this route, do you have any recommendation for a low-profile junction box (i.e., as close as possible to the ground)?

Thanks for any advice you can provide,
Dan
 
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Old 08-07-13, 09:54 PM
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Welcome to the forums!

I would extend the pipe and pull new individual THWN conductors into it. That said, you can use a PVC junction box to make a splice, and bury it so that the top of is flush with the ground. Something like this: 442PJ NEMA, Screw Cover, Enclosure.
 
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Old 08-08-13, 09:43 AM
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There are listed UF splice kits that can be buried.
 
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Old 08-08-13, 02:23 PM
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An above-ground junction-box at a location that will be at the "end" of the run of the existing PVC and the "start " of the run of the new PVC to the garage.

This requires two PVC elbows , one on the existing PVC and one on the new PVC , each elbow forming a horizontal-to- verticle transition for bringing the two ends of the PVC's above-ground to the junction-box.

You will have to with-draw the UF cable to a point just short of the new JB location so you can cut through the existing PVC without cutting through the UF cable. You need to fasten a "hook" or "loop" on the end of the UF cable so that after the PVC is cut , you can "catch" the end of the UF cable with a fish-tape hook and pull the cable to it's new termination.
 
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Old 08-08-13, 03:07 PM
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There are PVC boxes rated to be set into the ground, with the cover flush with the top of the soil.
 
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Old 08-08-13, 07:28 PM
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I got lucky on this one. After pulling the existing wires out from the garage and the conduit near the garage, it turns out that I have just enough wire to redirect down and back to the gravel and reach above ground level at the garage. So I can use a standard inline outdoor junction box attached to the outside garage wall. Sweet! Thanks for the advice.

However, you may have noticed in the picture that there are actually 2 conduits: one with a couple of 110 volt wires (my original focus of this post), and another with some low voltage wires (CAT5, Coax, speaker). Since I had plenty of slack in the low voltage lines, I assumed that I might be able to pull those wires towards the garage, since I thought that there's only one 90 degree bend from the house to the gravel area. Nope! Three of us pulled on the wires, but nothing happened. Finally, we tried pulling just the coax (RG 6/U Quad). The wire broke on the left side of the gravel area. Tomorrow, it looks like I'll be installing a junction box at that point (and then painfully joining each of those wires to a new terminal end). I'll try to use one of the at-ground-level PVC boxes that were recommended. But since it's low voltage, I'll likely install it at the level of the conduit (6-12 inches below the ground level). Is this reasonable and effective? Or, am I setting myself up for a future maintenance problem?
 
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Old 08-08-13, 07:48 PM
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A naive question on the PVC junction box you referenced. (I saw some very similar at Home Depot). How do you get wires into the box? There are no conduit connections or knock-outs. Do you just drill a hole in the side or bottom?
 
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Old 08-08-13, 08:03 PM
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Yes.....there are no knockouts because they could leak.

You can drill a hole with a hole saw or unibit (also called a step bit).

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A little pricey but great to have around. I use them almost every day. Available at box stores as well as electrical supply houses.
 
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