Underground wire size question

   / Underground wire size question #1  

bfisherman11

Silver Member
Joined
Apr 20, 2015
Messages
104
Location
IL and WI
Tractor
LS G3033H
I have a small building i want to run about 20-30amps in 110V to. My run is 180 feet from my electrical panel to the building.

I have searched "electrical" and gone back 8 pages to no avail.

I won't be welding etc. All i want are about 6 light fixtures (LED) and a couple outlets for a drill or hand saw.

I don't have any 220v needs....

Would say #10/2 with a ground work? I was having trouble looking at charts and understanding on line. I am not an electrician.

Thank you!
Bill
 
   / Underground wire size question #2  
You are well covered for 20 amps with a 10/2 at that distance. I would probably run 10/3 and have 2 110v circuits. Even though new code no longer blesses sharing the neutral.
 
   / Underground wire size question #3  
10-3 with ground to a sub panel in your building.
 
   / Underground wire size question #4  
10 /2 would be fine for what you want are you going to put a small panel in shed if so you may want to run 220 amp and run 10/3 so you get 2 hot 1neutral and 1 ground not much more money !!!
 
   / Underground wire size question #5  
10 /2 would be fine for what you want are you going to put a small panel in shed if so you may want to run 220 amp and run 10/3 so you get 2 hot 1neutral and 1 ground not much more money !!!

This option might also allow you to upgrade to 220 if you needed to at some later date for a at this time unknown need. Without having to rerun new wire.
 
   / Underground wire size question #6  
You are well covered for 20 amps with a 10/2 at that distance. I would probably run 10/3 and have 2 110v circuits. Even though new code no longer blesses sharing the neutral.

Can you expand on that? Not an electrician, just curious what has changed. Thanks.
 
   / Underground wire size question #7  
New code in my area says each circuit has to have its own neutral and ground. So, if you run a 10/3 to a small panel you can put a couple breakers in, you would splitting the hots and sharing the ground and neutral for each circuit. To stay within code, you would run two 10/2 WG so each circuit has 3 wires. It sounds like we are making this into more than what you actually need (it's what we do here), if so stay with the 10/2 plan and then run #12 wires out of a junction box to your lights and plugs.
 
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   / Underground wire size question #8  
If you are going through all the trouble to dig the line, ditch10/2 or 10/3 and put in conduit- 1 1/4". Then pull the needed size wire. With the length you are running you will need to upsize (per code recommended) one size. So #10 for 20a and #8 for 30a. All the sizes assume copper wire. To google the answers check out/Google

NEC T3705.1 (note code has maximum amps for 14,12and10awg)

NEC 210.19 fpn no. 4
 
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   / Underground wire size question #9  
If you are doing this as cheap (and as easy) as possible, you can run direct burial romex and run into conduit where you enter the panel and at the building. Just be aware you are potentially creating a termite super highway.
 
   / Underground wire size question #10  
As an absolute minimum in a conduit from panel to shed .10/3 from a pair of 20amp breakers in the main service. A set of 20amp T-slot receptacles for power tools on one circuit. All the lights and a couple of receptacles for low draw loads such as a radio on the other circuit.
This way if you trip the breaker to the power tools the lights won't go out. Also the lights won't brighten and dim as much when ever a power tool is started.

Far better to go with what other posters have stated with a 1-1/4" conduit, pull #8 wires, two live lines a neutral and a ground. 30 amp breaker in supply panel. 30 amp panel in shed, floating neutral bar with a pair of 20 amp breakers. Ground rod at shed, do not under estimate lightening. Sooner or later you will install an electric heater for winter, an AC for summer , a beer fridge and a microwave.
If over loaded, the 20amp breaker in the shed should trip instead of the 30amp breaker in the house.
 
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