Electrical for outdoor shed

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Old 05-02-16, 10:52 AM
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Electrical for outdoor shed

I recently purchased a shed and am looking to bring electric into it. My plan was to add a breaker to my existing panel in my house and bring it into a sub-panel in the shed. The total run is around 75 feet or so. I was going to dig a trench and put PVC conduit underground.

My question is what gauge wire do I need to run? What type of wire does it need to be in order to be run underground?

What kind of breaker panel can I put in the shed? Does the main breaker have to match the breaker in my house feeding it?
Thank you!
 
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Old 05-02-16, 11:07 AM
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The size of the feed and panel depends on what you expect to need or do out in the shed.

The panel does not need to match the house panel.

You can search this forum for many of the same questions to get more information and ideas. It is a popular topic.
 
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Old 05-02-16, 11:17 AM
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Why do you need a subpanel? What are you going to have in the shed that requires more than two 20 amp 120 volt circuits. (You can have up to two 20 amp 120 volt circuits without a subpanel. Only when you need 240 volts and/or more than 30 amps 120 volts do you need a subpanel.)
 
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Old 05-02-16, 04:29 PM
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Use UF style cable or THWN style single conductor wires.

One neutral accompanied by ground and two hots is the maximum allowed. Size would be 12 gauge copper for 20 amps on each hot for a maximum of 40 amps at 120 volts.

Use 10 gauge for 30 amps on each hot or 8 gauge for up to 40 amps on each hot.

The two hots must be wired into the house panel so as to have 240 volts between them even if you are not using 240 volts out at the shed. (The only other possibility is 0 volts between the two hots and still 120 volts hot to neutral.)

Even if you run 10 or 8 gauge wiring to plan for the future, you don't need to put the subpanel in the shed until you upgrade the breaker back at the house panel to be more than 20 amps.
 
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Old 05-05-16, 03:53 PM
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Thanks for all the great feedback. I was trying to make it so there would be another layer of safety, if something shorts out.

So I could use 10/3 cable, hook the neutral up to my neutral in my panel in my house, and the other two wires would serve as my hot wires? Just with 240v between the two of them?

Can I run them all in the same conduit underground?

Would I simply use a GFCI to prevent it from shorting out/electrocuting the user in the shed?
 
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Old 05-05-16, 04:16 PM
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If you use 10-3 you need to limit the breaker to 20 amps or install a subpanel at the shed with 20 amp maximum breakers.

The shed receptacles require GFI protection.
 
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Old 05-05-16, 04:28 PM
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Can I run them all in the same conduit underground
It is required by code they be in the same conduit.
So I could use 10/3 cable
You only need 12-2 for your distance. (20 amp max for general purpose 120 volt circuits.) However best practice is not to run cable in continuous conduit. If you want to use conduit you would use individual wires (usually THWN). You would use two black (or one each black and red), one white, one green.
Would I simply use a GFCI to prevent it from shorting out/electrocuting the user
Breakers prevent it from doing damage when it shorts. GFCIs protect people. You can use one GFCI receptacle to protect a string of receptacles by using it as the first one.

You will need a disconnect on the cable at the shed. That can be as simple as a 2-pole 20 amp switch or an unfused air condition disconnect switch. (The latter might actually be cheaper then a switch and box.)
 
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Old 05-07-16, 10:47 AM
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Wow thanks again for all the great advice! I was thinking of using the 10 (or 12) -3 wire so I can run two hot wires out to the shed, so in turn if down the line I need to add a space heater or something similar I can have another circuit to tap into.

If i'm not mistaken, the 12-3 wire has 3 wires and a ground, so 1 would be neutral and the other 2 would be my independent hot wires.

Is there an electrical enclosure box that can handle the 2 lines coming out with 20amps? I'm having a little trouble locating what I would need.

Once again, I appreciate all the feedback!
 
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Old 05-07-16, 11:11 AM
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Is there an electrical enclosure box that can handle the 2 lines coming out with 20amps?
Many electrical boxes except for very shallow ones can handle two 12-3 cables. Usually a 4x4 box is used. If you are talking about for the disconnect at the shed if you used an unfused air conditioner disconnect the box that it is a part of is all you need.

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if down the line I need to add a space heater or something similar I can have another circuit to tap into.
Then you might want to run 10-3 as you suggested. It will still be on a 20 amp breaker for your multi wire circuit but it could easily be converted to a 30 amp subpanel if you found you need more power later.
 

Last edited by ray2047; 05-07-16 at 11:49 AM.
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