[dalepres]

I'm working on internal wiring on my shed. I just put in a breaker panel fed by 6 gauge THWN from the house.

I want to use 3/4 EMT running along the top of the wall, use a T type conduit body every three feet to drop down to a surface mount 21 CI 4x4 metal box. The box will serve as dual-gang duplex receptacles.

So there will be hot, neutral, and ground coming into each of the metal boxes attaching to the receptacles, short jumpers between the receptacles, and then hot, neutral, and ground leaving from the receptacles back up through the conduit body and over to the next drop three feet away.

I'll use a pre-made ground screw lead to attach the grounds to the box so there will have to be a yellow wire nut for four 12-gauge ground wires. That is one ground in, one ground out, one pigtail from the outlets, and the ground wire to the box.

I used the fill calculator at http://www.constructionmonkey.com/calculations/electrical/boxfill and, if I did it right, I'm ok on box fill. I counted four wires terminating in the box - two in and two out. I didn't count the ground as a terminating because the ground appears to be calculated separately.

Am I correct that I am good with this scenario for box fill? There are box extenders for those metal boxes that I can easily slip in if required but I'd prefer not to just from aesthetics and mechanical solidity (or rigidity?) perspectives.

Also, is it OK to use the conduit body T's as I described?

Thanks.

 

[Jim Port]

The T is not even needed. Just run the conduit box to box.

All grounds count as one towards box fill. Each device counts as two conductors. I would use a deep 1900 with raised covers.

A yellow nut is typically not good for 4 #12's. Use a red one.

1/2" EMT is large enough for 3 #12. No need for 3/4".

 

[dalepres]

Thanks, Jim. I guess I should have provided more details. I tend to get long winded so I tried to keep it short.

I had intended to edit yellow to red on the wirenut before submitting and never got back to it.

I could run the conduit box to box but I wanted the conduit run at the top of the wall and the outlets at bench height - but I may be over thinking this.

There will be 6 outlet boxes in the string. I was thinking of dividing them across two or possibly three circuits. I know I could also reduce conduit fill by skipping the ground wire but I'd prefer to have the ground wire, too. Again, maybe I'm over thinking it. So three circuits of three wires takes me to 9 - the upper limit for #12 in 1/2 EMT.

I can't find a deep 1900 box anywhere near me so I'm stuck with the box I have and can add a half-inch or a 1.5 inch extension sleeve.

 

[Jim Port]

You only need one ground for all the circuits.

 

[ddawg16]

You only need one ground for all the circuits.

Because it's considered non-current carrying.....

On a personal note....I tend to upsize conduit for my personal stuff. Just makes life easier down the road...because I've found I usually end up adding stuff later....

But that is me.

 

[Arrow3030]

T's are kind of a pain to work with. I'd recommend 4 squares instead. Remember that you only have to count a wire once if it goes straight through a junction (no wire nuts) and doesn't have a loop in it.

 

[dalepres]

Very helpful responses, all. Thanks.