Passing EMT conduit through a box

[600SL]

I would like to run two duplex outlet circuits with an outlet every 5 feet and each circuit powering every other outlet. It would save a lot of trouble if I could pass the EMT conduit right through the box to avoid bending around the boxes. I cannot find anything in the code that says you cannot do this but I never seen it done. I have attached a picture to show how the conduit would either pass through or terminate within the boxes.

The only thing I can think of is that I would have to subtract the volume of the EMT from the box volume. This should still leave plenty of volume because I will be using 3.5" deep boxes. The code states that conductors that pass through the box don't count but it doesn't say anything about conduit passing through the box.

Your thoughts?

John

 

[Mustang51js]

You only need one pipe from box to box,if you wanted two circuits then you pull black,red,white and green if you want an extra ground. Then your just passing the wires through one box to the next.

 

[Gooch]

I would like to run two duplex outlet circuits with an outlet every 5 feet and each circuit powering every other outlet. It would save a lot of trouble if I could pass the EMT conduit right through the box to avoid bending around the boxes. I cannot find anything in the code that says you cannot do this but I never seen it done. I have attached a picture to show how the conduit would either pass through or terminate within the boxes.

The only thing I can think of is that I would have to subtract the volume of the EMT from the box volume. This should still leave plenty of volume because I will be using 3.5" deep boxes. The code states that conductors that pass through the box don't count but it doesn't say anything about conduit passing through the box.

Your thoughts?



John

why do you need two pipes? just run one with two circuits in it.

 

[tshetter]

One conduit, two circuits.

Don't over think it.

 

[600SL]

You only need one pipe from box to box,if you wanted two circuits then you pull black,red,white and green if you want an extra ground. Then your just passing the wires through one box to the next.

That's called an Edison Circuit. Not legal in many places. Its legal here but requires the two breakers to be bridged, which defeats the purpose.

JR

 

[600SL]

One conduit, two circuits.

Don't over think it.

4 conductors requires de-rating. 10 gauge wire is expensive.???

 

[volleyball]

That's called an Edison Circuit.

JR

not illegal if in a metal conduit.

I am pretty sure there won't be enough room to do what you are thinking. One conduit is all you need. A white for each circuit ensures no issues.
I would think if you offset your boxes so the conduit would pass over/under the other set, you have what you want

 

[tshetter]

Run it as a 240v circuit from the panel box, with 240v breaker, with each leg going to each set of receptacles.

I have no idea about electrical code, so I cannot advise to the legalities of that. But I would think that this would be a decent solution.

 

[600SL]

not illegal if in a metal conduit.

I am pretty sure there won't be enough room to do what you are thinking. One conduit is all you need. A white for each circuit ensures no issues.
I would think if you offset your boxes so the conduit would pass over/under the other set, you have what you want

The Edison circuit or shared neutral is legal here in NC. But would require bridging the two circuit breakers there by making them effectively one circuit. This is what my local inspector told me.

There is definitely enough room in a 3.5" deep box.

I would have loved to run 4 wires in one conduit but the way I understand the code, over three requires de-rating, driving the wire gage from 12 to 10.

I have considered the over under but I think it wouldn't look very nice.

Right now this looks like the cleanest option but haven't seen it in use.

 

[Aceman]

but I never seen it done. I have attached a picture to show how the conduit would either pass through or terminate within the boxes.

Nobody does it that way because you only need one conduit.

You're only required to use a 2 pole breaker if the two circuits are sharing ONE neutral or both circuits land on the SAME duplex receptacle.

If you are running two hots and two neutrals leapfrogging your boxes two single pole breakers will suffice. You have no issues using #12 thhn, derating is not a problem.

 

[600SL]

Run it as a 240v circuit from the panel box, with 240v breaker, with each leg going to each set of receptacles.

I have no idea about electrical code, so I cannot advise to the legalities of that. But I would think that this would be a decent solution.

Yes this is OK here in NC but the but the use of the 240V circuit breaker would effectively make it so that if one circuit went out they all would go out.

 

[Mustang51js]

4 conductors requires de-rating. 10 gauge wire is expensive.???

How big of a garage is this that you would need 10 wire for general receptacles. How many outlets do you want. Seems like this is being way over thought, I believe your allowed 9 #12 thhn in a 1/2 emt.

 

[volleyball]

What type duplex outlets? 15a, 20a, 30a? Is there some reason you want that deep a box? If it wasn't out in the open, the staggering wouldn't show and if it is, will it be banging your legs. Or are they going to be higher?
A larger single conduit should solve your derating issue if I understand correctly.

 

[600SL]

Nobody does it that way because you only need one conduit.

You're only required to use a 2 pole breaker if the two circuits are sharing ONE neutral or both circuits land on the SAME duplex receptacle.

concur

If you are running two hots and two neutrals leapfrogging your boxes two single pole breakers will suffice. You have no issues using #12 thhn, derating is not a problem.

OK now you have me reaching for the code book. My understanding was over 3 current carrying conductors required derating. I am using #12 thhn. Is it 3 current carrying conductors or 3 hots or do I just have this all wrong?

Thank JR.

 

[kaffine]

4 conductors requires de-rating. 10 gauge wire is expensive.???

Even after de-rating 12awg wire should still be good for a 20amp breaker.

If you really want to run 2 conduits then terminate all the conduits and just have the wire pass through the box without being terminated. Need to account for the wires passing though when looking at box fill though.

I wouldn't try to pass the conduit itself through the box.

I would look at using 4" square boxes with a mud ring so it takes receptacles and set them up as quad boxes. This way each outlet box would have 4outlets and each duplex would be on different breakers.

 

[600SL]

How big of a garage is this that you would need 10 wire for general receptacles. How many outlets do you want. Seems like this is being way over thought, I believe your allowed 9 #12 thhn in a 1/2 emt.

Yes for the fill tables its something like 9 conductors. My understanding and I'm hoping I'm wrong, is that once you go over three conductors the ampacity of the wire needs to be derated. Therfore #10 wire would be required on 20 amp circuits.

Garage is 30x48

 

[600SL]

What type duplex outlets? 15a, 20a, 30a? Is there some reason you want that deep a box? If it wasn't out in the open, the staggering wouldn't show and if it is, will it be banging your legs. Or are they going to be higher?
A larger single conduit should solve your derating issue if I understand correctly.

These will be 20 amp outlets. boxes will be about 4' off the floor. If I can get 4 conductors and a ground into 1/2" EMT without derating that would be good.

 

[rockwithjason]

you can use the 90 degc column when derating thhn. that means you are ok in this application

 

[600SL]

you can use the 90 degc column when derating thhn. that means you are ok in this application

OK just looked this up. Using the 90° C THHN column I'm good for 30 Amps at 80% derate I'm still good to 24 Amps.

Hell maybe I can pack some 240V circuits in there as well.

Thank You gentlemen.

 

[600SL]

Even after de-rating 12awg wire should still be good for a 20amp breaker.

If you really want to run 2 conduits then terminate all the conduits and just have the wire pass through the box without being terminated. Need to account for the wires passing though when looking at box fill though.

I wouldn't try to pass the conduit itself through the box.

I would look at using 4" square boxes with a mud ring so it takes receptacles and set them up as quad boxes. This way each outlet box would have 4outlets and each duplex would be on different breakers.

Thanks

I did come to the conclusion that #12 derated will still be good for 24 amps

I would have loved to use 4" square boxes but they wont fit with my corrugated steel wall panels.

Looks like I have this figured out with a single conduit.

Thank
John

 

[CoopVA]

Nobody does it that way because you only need one conduit.



You're only required to use a 2 pole breaker if the two circuits are sharing ONE neutral or both circuits land on the SAME duplex receptacle.



If you are running two hots and two neutrals leapfrogging your boxes two single pole breakers will suffice. You have no issues using #12 thhn, derating is not a problem.

This ^


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[rev1]

I plan on doing the same thing, run two complete circuits (two hot, two neutral, and one ground) 12awg in EMT with every other receptacle on the same circuit for a total of 4 receptacles on each circuit, maybe one quad in the middle of the run with both circuits in that box. To plan for possible additions later, should I use 3/4" EMT instead of 1/2"? Also, I'll have some 8 awg running in a separate EMT for 240v and plan to use 3/4" for that. Should I run a combination of 1/2 for 120 and 3/4 for 240 or run all 3/4"?

 

[Mustang51js]

I would run 3/4 and pull all the wires in one pipe, but use a deep 1900 box so the outlet isn't pushing the wires into back of box. I would pull one neutral for the two 120v lines but doesn't hurt to have the extra neutral, you also don't need a ground wire with the pipe just tails going to the outlets from the back of the box.

 

[Delta74]

cant speak on the NEC if you were up north and used the CEC I would say hell no not code legal. but I would bet that conduit THRUE a box would be a huge no no, if its like ours, just terminate conduit at box, pull thrue box into new connector and conduit.

again, not up on the NEC, but the conduit if using EMT would act as a ground so could just pull 2 hots ( black and red ) and a single white,just make sure the two breakers are not on the same leg at the panel, example spots 1 and 2 instead use 1 and 3 since most panels alternate each breaker spot per side between each of the two feeds.

again, cant give solid advise, but I don't think you would need to use a tandem breaker sharing the Neutral, here we don't NEED too, just tag the neutral as having 2 circuits so you can shut off BOTH circuits later if you need to work on either one. have got some wicked shocks off the white from being shared on 3 circuits ( 3 phase panels )

 

[600SL]

OK at least I'm all calibrated and up to speed on this. I will be pulling 2 hots and two neutrals. One hot will be red the other will be black. and may be 2 other colors for a 240 circuit.

Now about the neutrals. since these will be two independent circuits will I have to keep track of which neutral goes to which outlet. For example one neutral stays with the red circuit and on stays with the black. Or does it not mater since the all go to the same place.

If it does matter is there any standard way to mark the neutrals.

 

[Tyberius]

OK at least I'm all calibrated and up to speed on this. I will be pulling 2 hots and two neutrals. One hot will be red the other will be black. and may be 2 other colors for a 240 circuit.

Now about the neutrals. since these will be two independent circuits will I have to keep track of which neutral goes to which outlet. For example one neutral stays with the red circuit and on stays with the black. Or does it not mater since the all go to the same place.

If it does matter is there any standard way to mark the neutrals.

Just get a gray. Or use tape of the hot color.