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Discussion Starter · #1 ·
I'm running power from my panel in the basement to an outdoor shed. I'll be using a 20 amp GFCI breaker with 12/2 NM until it exits the house where I'll use 12/2 UF to continue to the shed. I'll also be running 12/3 NM from a basement light switch until it exits the house where I'll bury 12/3 UF to the shed along side the 12/2 UF. Inside the shed I'll go back to 12/2 and 12/3 NM. The 3-way switch in the shed is where I'll pick up the power (not the 3-way switch in the basement.)

My question is this: In the junction box where I leave the basement, can I wire-nut the ground wires on the 12/2 NM and 12/2 UF separately from the ground wires of the 12/3 NM and 12/3 UF making each run a simple extension of the length of wire? Or do all four ground wires need to be wired together? And the same question goes for the junction box inside the shed just after the LB. When the power is attached to the 3-way switch in the shed the ground wires from the source, the lights, and the 12/3 wire between switches would be pigtailed to the ground screw on the switch creating the ground back to the panel.

It just seems the 12/3 wire is completely separate until there is power to that switch and may not have to have all 4 ground wires wire-nutted together at each junction box.

Am I missing something? Thanks in advance!
 

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So it sounds like you want a switch in the basement that's a 3-way with the shed switch so you can turn the shed lights on/off from the basement?

I would wire from the panel to the switch in the basement with 12/3. Use the red as the hot (common) for the switch and the black to pass through power for shed outlets. Come out of the switch box with conduit and run THHN (individual wires) to the shed. Use a black, white and green for the primary conductors and connect those to the black, white, and green on the 12/3 going into the basement switch box. Now you just need to add two "travelers" between the two switches, so pick two other colors, maybe brown and blue.

In the shed, use the switch box as the junction box on the shed end. Connect the brown and blue travelers to the 3-way switch and the hot to the light on the common terminal of the switch. Then use the black white and green as continuous power for outlets. Tie the neutral from the light into the white and ties all the grounds into the green.

This allows you to run 5 wires instead if 7, plus conduit doesn't have to be buried as deep as UF.
 

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If the shed is detached, you can only run one circuit. Good advice on running THWN in conduit. Easier and less restrictions.
 

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Discussion Starter · #5 ·
Thanks to DIY Sparky. I feel pretty comfortable with running the 12/2 UF just 12 inches underground in my location. The 12/3 is only to accommodate the 3-way switches and seems like overkill, but, again I feel comfortable at that skill level. Just bring the power to the shed and send 80 feet of 12/3 back to the basement for the 3-way. I can split the power off at the shed for outlets and lights.

I just wasn't sure about the ground wires and joed just mentioned ALL ground wires meeting inside a junction box must be tied together. So, I appreciate that to. Thanks for you advise!
 

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The 12/2 brings power to the shed, and the 12/3 runs back to w 3-way switch in the basement that controls a light in the shed. To the OP, certainly nothing wrong with doing it that way, was just trying to make it easier for you.
 

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Discussion Starter · #9 ·
I've been thinking about your idea of running 5 wires through conduit to my shed instead of one 12/2 and one 12/3 UF. Do both the red and black wires get attached to the 20 amp GFCI breaker somehow? Or is there a special breaker? That's what's confusing me. Hate to bother you again after your answers yesterday. But now I'm curious about your plan.
 

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My mistake...run a 12/2 ftom the panel to the basement switch. In the switchbox, wirenut pigtails from the black to the common on the switch and the bkack going to the shed to feed the outlets. Sorry for the confusion!

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