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One location is a 3 vehicle carport which I just need some lights, 2 ceiling fans and some receptacles. Nothing too fancy except it might be nice to be able to run a compressor in there for working on vehicles or woodworking things. The builder already put a 50 amp service on the side of the house anticipating this project. It's 75' from the house.

The other location is where there is a concrete pad from an old mobile home. I would like to put a 12 x 20 shed on that slab and use the building mostly for storage and maybe small stuff like running a drill and maybe a chop saw. Having a 6000 btu window AC would be a dream if possible. It's 75' in the attic and then 100' outdoors to the shed location.

Because of the mobile home having been there, I found the ground rod when I was doing irrigation, so I ran my trench to that location for the shed electric assuming it would be useful.

Please look at my drawing and photo. You can almost make out the concrete slab on the right in the photo.

I happen to have a 100' roll of 8/2 romex which I would love to be able to use in the attic portion of the shed electric project before transitioning to the UF cable outside.

Because it's heading into the hottest part of the year, I just want to put the UF cable in the ground until fall when the rest of the project will be completed. I did the trenching for this electric when doing the irrigation project.

Please advise me if I can do a 30 amp subpanel at the shed with the 8/2 in the attic and ? for the 100' from house to shed. House was built last year and I'm sure I have room in the main panel. What kind of UF cable to buy and lay in my trenches to the shed and to the carport.

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  • The pros will come along and give you all the details. But generally speaking, you need to use /3 cable (or 3 wires in a conduit) rather than /2 - i.e., you need hot/hot/neutral - that extra wire means instead of either 240V-only (hot/hot which is fine for big stuff and lighting but a problem for "ordinary stuff") or 120V-only (hot/neutral which means you only get one leg of 30A instead of 2) you get 120/240 and can do "anything". Also seriously consider putting in larger cable - 6 AWG will (I think) get you up to 50A with reasonable voltage drop, and that gives you a lot more flexibility May 26, 2019 at 21:50
  • 3 wires in a conduit only applies if the conduit is conductive, and conductive conduit suitable for burial is a LOT more expensive than PVC conduit and a grounding wire (the one not counted in cable designations, but there), last time I shopped. I will always prefer conduit to ANY direct-burial cable...
    – Ecnerwal
    May 26, 2019 at 22:05
  • Are there any reasons you'd want to use a direct-buried cable instead of conduit here? Also, where on/in the house is the actual service panel that you'll be running from, or do you plan to run both circuits from the 50A subpanel on the outside of the house? May 26, 2019 at 23:36
  • The electrical panel in the house would be used for the shed. That would be a distance of 75' to the exterior of the house and then another 100' to the shed.
    – Ninarina
    May 27, 2019 at 1:43
  • May end up doing conduit, still assessing costs. Little chance of it being disturbed since I did the trenching already myself. Throwing UF cable in the trench is appealing when it's already this hot in Florida.
    – Ninarina
    May 27, 2019 at 1:44

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