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I am getting 100 amp service connected to my cabin (currently off grid). The power company wants me to install my meter base on the corner of the property, and for me to install 200' of underground conduit from the meter base pole to my cabin.

I plan to install a main panel on the meter pole, feeding a sub panel hung on the side of my cabin.

My question is, what type of wire should I use for the underground run? Also, do I need to ground the sub panel at the cabin as well?

  • Gene where do you live? Is there exposed rebar in the foundation that can be used for your ground? You will need a minimum of 1 electrode depending on location and many times a second 8' ground rods are the norm if there is no connection to the rebar. here is a handy voltage drop calculator so you get your wire sized correctly. – Ed Beal Apr 15 '16 at 21:37
  • Thanks Ed. I am in Yucca Valley. No exposed rebar connection available. I used the voltage drop calculator you mentioned and it's recommending I use #1 copper or #1/0 aluminum. I am having trouble locating 4 conductor cable with these specs that is intended for underground service. Do all conductors need to be part of one cable, or can I do separate runs through the conduit adding up to 4 properly sized conductors? – GeneSane Apr 15 '16 at 22:11
  • @GeneSane you don't have to use a cable, individual conductors are fine (and probably easier to pull). – Tester101 Apr 16 '16 at 1:13
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You'll have to use a cable or wires that are rated for wet locations. You'll most likely use Underground Feeder (Type UF) cable, Underground Service-entrance cable (Type USE) , or THWN wires.

You'll have to install a proper grounding electrode at the cabin, and bond the grounding conductor to it.

You'll have a grounding electrode at the pole, where you'll bond the service neutral and the equipment grounding conductor. From there you'll run four wires (two "hots", one neutral, and one ground), and you'll keep the ground and neutral separate.

  • @GeneSane ground and neutral are separate everywhere after the service equipment. Neutral is bonded at the service drop, the meter, or the service disconnect. After that, neutral and ground are separate conductors. – Tester101 Apr 15 '16 at 21:46
  • Thanks! Any advise on where to get 4 conductor cable approved for underground service? For the wire size I need, I can only find 3 conductor. I must not be shopping at the right places. – GeneSane Apr 15 '16 at 22:13
  • @GeneSane You might see Type USE sold as SEU (Service Entrance Underground) cable. You'll want 2-2-2-4 SEU AL (4-4-4-6 SEU CU), unless your voltage drop calculations tell you to up size. Go to your local electrical supply shop, tell them what you're doing, and they should point you in the right direction. – Tester101 Apr 15 '16 at 23:42
  • Also, if you're planning to pull cable instead of individual conductors, make sure you do your conduit fill calculation based on the actual size of the cable. – Tester101 Apr 15 '16 at 23:49
  • There are electrical supply houses all over your area who specifically deal in code electrical, and that's where electricians go. Two reasons: #1 they have everything (electrical, anyway - not Kit Kat bars, USA-flag house keys or paint)... #2 price. Oh and #3, time - you'll see. – Harper Apr 15 '16 at 23:50

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