Breakout box above panel???

[terabitdan]

Hello I’m installing a new sub panel and wonder if it’s to code to use EMT conduit from the panel up into the joist bay above, then attach a 4x4x4 box to use as a breakout box for NM cables? It’s less than 24” and I would run the NM through the box and conduit, stripping the jacket inside the panel with no splices. Doing it this way would provide a neat way to clamp all the NM and seal off the top of the raceway.

I know it’s ok to use the conduit and end it in the joist bay, just not sure if the box on the top makes it a raceway system.

There are five 12/2 NM which would go through the raceway, 2-2-2-4 SER, 1” and two 1/2” additional conduits coming from the 24 space panel. The wall will be finished on both sides which is why I want to use the conduit to protect the wires and make additional circuits easy to feed it needed.

Appreciate the help...

Dan


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[mike93lx]

4x4x4 feels way too small for all that stuff, plus leaving room for future expansion. Did you do the Calc for volume? I feel like something wider or multiple would be a lot easier to work in

 

[pattenp]

The EMT used in the manner you are asking from panel to a box is considered a complete raceway and the EMT and box needs to be sized according to fill limits.

 

[terabitdan]

I have not completed a fill calculation as I’m trying to avoid the complete raceway designation. All I wanted was 16” of conduit to feed the NM cables through. I’ll run a calc just in case. The other conduits and SER are not going into the 4” square box, only the 5 NM cables.

If it’s a complete raceway then can the NM run through it as I described?

As for expansion, this panel is just for my kitchen renovation and new half bath. I’m going crazy with circuits. 6 countertop circuits for example. There may be one or two in the future but I have plenty of space in the existing panels.


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[terabitdan]

Thanks for your replies. I calculated box fill for 7 12/2 NM not terminated in the box requires a 4 11/16 x 2 1/16 minimum standard box size. At 7/16” wide they easily fit in the 40% conduit fill for a 2” conduit. Up to 9 according to my calculations. So with a 4” cubed box that would give more spare room to work.

Out of curiosity I also ran the calculations for all the conduits except the SER passing through a box with a single 2” into the panel. It easily fit in a 6x6x4” box but only six NM would fit within the 40% conduit fill.

Of course, my math could be off...

So, even if my inspector considered this a complete raceway it looks doable.


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[brewchief]

With that many current carrying conductors you will do do some derating and may find that it won't work the way you want it to.

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[terabitdan]

If I understand the derating rules correctly, cables in raceway or conduit less than 24” long there is no derating.

I also just found reference in the code that conduits less than 24” also have a maximum fill of 60%. I used 40% in the above calculations.

From Mike Holt training....
Notes to Tables, Note 4—Raceways not Exceeding 24 Inches
When a raceway doesn’t exceed 24 in. in length, it’s permitted to be filled to 60 percent of its total cross-sectional area as identified in Table 4 of Chapter 9. Figure 5–11

And https://forums.mikeholt.com/threads/******-derating-factor-code-reference-310-15-b3a-2.145882/ for example states that derating does not apply to conduit or raceway less than 24” long.

The only way I can or would do this is under that exception, otherwise it makes no sense.

I couldn’t find the actual code link or I’d post that.


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[alfredeneuman]

Why don't you use individual wires to the box instead of NM?
All of them would fit in a 3/4" conduit with room to spare.

 

[Innovate1]

Here they allow conduits from the top of the panel up to the joist space with no box at the end. And you said it was ok there also. So why the box? In this case the conduit is for protection only. Best to check with the AHJ to see what they want/allow.

 

[terabitdan]

Alfred, I could definitely follow your suggestion. If this were a larger panel (24 spaces) it would be compelling. After doing the research in response to the questions posted I’m leaning toward connecting all conduits and romex into an 8x8x4 box, running all 17 circuits through the 2” conduit, probably 2 for that matter, why not?

But to terminate them just to use more smaller conduits seems like more work for little benefit. If the 24” exception weren’t there, or due to the layout I couldn’t take take advantage of it, then it would make more sense to me at least.

The long story is this panel is for a kitchen remodel & a new half bath. With all the required dedicated circuits, combined with AFCI/GFCI regs the existing 30/40 and 24/30 panels didn’t have enough space. The existing panels are on one side of the stairs in the basement, kitchen on the other, so every new one has to route around the stairs, in a finished basement. So this panel just needs to service the kitchen, and I’ll have freed up a number of spaces in the existing panels.

Thanks for the idea, wish I had thought of it when doing the main panels. It would have cleaned up an ugly rats nest another the panel.


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[terabitdan]

Inovate1 - I want the box to cleanly clamp the romex. With an open conduit it’s supposed to be sealed to protect from anything entering into the box. Plus stapling each romex as it leaves to box. Of course it’s doable, but I think this will look better and provide Easy access to add/replace new circuits if that should ever arise.


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[terabitdan]

Thanks for the suggestions. Here’s what I ended up doing...



The 2” on the right side of the panel is for the 2-2-2-4 SER, the other two are for the circuits through the 8x8x4 box.

The Romex and MC you see I’m moving to the other side of the joist bay.


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[theoldwizard1]

Hello I’m installing a new sub panel and wonder if it’s to code to use EMT conduit from the panel up into the joist bay above, then attach a 4x4x4 box to use as a breakout box for NM cables? It’s less than 24” and I would run the NM through the box and conduit, stripping the jacket inside the panel with no splices.

Code gets funny for long run of stripped NM. I would get it in writing from the Authority Having Jurisdiction (AHJ).

You might consider going to a 4x12x4 box.

 

[mike93lx]

Thanks for the suggestions. Here’s what I ended up doing...



The 2” on the right side of the panel is for the 2-2-2-4 SER, the other two are for the circuits through the 8x8x4 box.

The Romex and MC you see I’m moving to the other side of the joist bay.


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I think that looks pretty good. Even remembered the bushings before you pulled any wires

 

[jeffmoss26]

Looks good!