New to the group, I have a shed which is about 65 feet away from the utility pole. I have a meter and 12 space box below where the previous owner ran 14/2 Romex underground from a 20A breaker. (Yes with the heavy rains, it shorted out. No damage caused) and I’m unsure if it’s in conduit.

Anyway, I’m re-running the one feed using 12/2 UF-B wire, and am thinking ahead to install a sub panel but don’t know what size. The shed has one outlet which runs to a switch above which then runs to two light fixtures. I have an upright deep freezer plugged in, and run an electric weed eater or power tools off the other plug.

I’d like to install a sub panel which will allow me to run new circuits for outlets (maybe 6) and a light fixture. I will be running power tools, computer and NVR (both running 24 hours a day) from this sub panel. What size should I buy and what size breaker should feed it from my main panel?

Sorry so long and thank you all.

  • 2
    The box size doesn't matter; heck, put in a 200 amp panel with 40 slots. The only thing that matters is the breaker size which protects the incoming line. 14/2 to a 20 amp breaker?? The previous owner had a deathwish. Since you're going through the trouble of running a new wire then why not upsize to a wire that can handle more amperage; like 50 amps? 12/2 is good for up to 20 amps depending on the distance. 12/3 can give you some MWBC advantages I think.
    – MonkeyZeus
    Commented Jun 24, 2021 at 19:05
  • 3
    If it's in conduit, 12/2UF may not be legal there due to conduit fill (UF is really wide). Also a sub panel generally requires /3 (3 wire + ground); neutral is not ground! Conduit really works best with individual THWN or XHHW wires, and ideally you go big enough that aluminum makes sense, and then you save a ton of money on wire. I would fully investigate whether you have conduit and choose accordingly. NM is not rated for outside, so no surprise it shorted. Commented Jun 24, 2021 at 19:19
  • 1
    Is there anything stopping you from running a conduit out to the shed? Commented Jun 24, 2021 at 23:21
  • If you're only using single 20A circuit 12/2 why bother with a panel at all? You will have all the overcurrent protection you can use on the feeder. The only requirement is for a switch rated for the load. Commented Jun 25, 2021 at 0:50
  • Thank you all for the information. Another question, is a 100A breaker to feed the shed over kill?
    – Kurt M
    Commented Jun 25, 2021 at 1:26

1 Answer 1


I agree with Harper, we suggest going bigger 12 awg on a 20 amp will work kind of.

My 12” chop saw kicks the breaker on long runs like that and it’s a 15 amp model.

Two long for a comment and this has been answered many times on this site.

Really consider 1-1/2” pvc conduit 7 sticks and a couple of 90 degree sweeps a little over 100$ and you have a future proof setup.

Put in a ~125 amp box or whatever is the best price sometimes bigger is cheaper.

Feed it with what you want today and use the appropriate breaker for the wire like copper #12 =20 amp.

when ready upsize the breaker and wire. Voltage drop will not be a problem at that distance.

I had a customer that did what you are doing 3 times! I suggested this method to start just like we have suggest to you. He had me put in UF wire and a tiny box Later bigger UF and a larger box The last time he did it right (he is now a fishing buddy). After the 3rd time he remarked “I now know why You have a nice boat to go fishing offshore”. Later he said he did not believe me at first he had the money to do the pipe but it was cheaper for just the UF.

You have to dig a deeper trench for UF that’s where the real work and cost is. 6” shallower with conduit. 1-1/2” will make an easy pull even if your next jump is for 50-125 amp rated conductors.

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