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I plan to install my service drop/meter/main disconnect panel on a post 200' from my cabin, which will have a 100 amp sub panel mounted on the exterior. I am having trouble finding 4 conductor service entry cable rated for underground use (will be running it through schedule 40 conduit).

Would 4/0-4/0-4/0-2/0 aluminum mobile home feeder service entry cable be suitable? The cable is rated for direct burial or in conduit (USE), and the conductor size is more than enough, but the word "mobile home" is giving me pause.

  • I am not an electrician but you should only need 3 wires, right? Since the main disconnect and sub panel will be in separate buildings you will want to have grounding rods at each location and only need hot 1, hot 2, and neutral wires. – Hank Apr 16 '16 at 0:16
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    Nope, it's a sub-panel so you need separate neutral and ground. If it wasn't... – Harper Apr 16 '16 at 1:12
  • @HenryJackson You need 4 conductors, and a grounding electrode at the second panel. – Tester101 Apr 16 '16 at 1:52
  • @Tester101: interesting. if the main panel and sub panel both have grounding rods what's the point of the ground wire between them? – Hank Apr 16 '16 at 3:20
  • @HenryJackson It's the effective ground-fault current path, which is required to clear faults. If there's a fault, you need a low impedance path back to the source, so fault current will be large enough to open the breaker. – Tester101 Apr 16 '16 at 10:08
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If you're running it through conduit, just buy single strand. It's cheaper. e.g. this
And obviously you'd be buying this at a proper electrical supply house, not the bigbox since they probably will not have it, and bigbox is really overpriced anyway. With wires of these sizes, it is not required to buy white or green wire for ground, you can designate that with tape.

Besides, it'd be murder to pull a 4-wire cable through conduit. Four single wires will be tough enough! Might want to bring in a commercial electrician simply for the pull because he has the gear on the truck to do the job easily.

  • Thanks Harper. Is it necessary to run it through conduit or is direct burial acceptable? Also, is the fourth conductor necessary for the ground, or can I just install a grounding rod at the sub panel? – GeneSane Apr 16 '16 at 1:03
  • Some wires and cables are made for direct burial. If it is a sub-panel, you must run 4 wires to it and cannot bond neutral to ground at the sub-panel. You may have a grounding rod there. – Harper Apr 16 '16 at 1:11
  • @GeneSane You need 4 conductors, and a grounding electrode at the second panel. You can use direct burial cable without conduit. – Tester101 Apr 16 '16 at 1:48

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