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I'm taking power from a 100 amp subpanel in an outbuilding and running three branch circuits: two to small outbuildings for lights, one to a horse waterer that draws 1.5 amps. Two questions: can I run the three UF wires in a single trench for the first 50 feet? Do I bring all three UF wires into the power source building in a single LB or do I put in three LBs?

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    I would conceiter putting in a small sub panel then you can have local breakers and will only take 1 larger feeder and can be taken to the separate locations from the box. – Ed Beal Jul 17 '16 at 15:50
  • He already has a sub panel, the problem I think he has is that he is wiring to 3 different locations, and wants to run the cables to a point of divergence which presumably is in the middle of his yard somewhere. There wouldn't be a place there to put a sub panel. – Harper Jul 18 '16 at 1:41
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IME, IMHO, UF is a terrible idea, but you can certainly put 3 UF in one trench, and you COULD bring them in through one (HUGE) LB - the LB needs to be HUGE because oval wire is treated as round wire of the largest dimension of the oval for conduit fill purposes, and 3 wires does not get the one-wire higher fill percentage. Also practically speaking you'll appreciate having the space to get the job done with less swearing.

I would STRONGLY recommend conduit and individual (wet rated) wires. The trench is the expensive part. Conduit means never having to dig the trench again, while direct burial means you might have to do that. Not infrequently conduit and wire is competitive with or actually cheaper than direct burial wire.

  • Seconding the conduit recommendation -- not having to oh, tear up a driveway because something broke or you needed more wires is a lot nicer than the alternative! – ThreePhaseEel Jul 17 '16 at 23:53
  • Yes, certainly if any of this goes under something paved, it should be all conduit. – Harper Jul 18 '16 at 0:14

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