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Old 01-29-2010, 03:51 PM   #1
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Short Wires in an Overfill


Recent discussions regarding my Unorthodox Sub-Panel remind me that my initial meeting with the local building inspector had been cut short, and I didn't get a chance to ask him about a particular problem with this install.

History: Before I knew as many details regarding Electrical Codes as I do today, I installed a pair of circuits in my garage to power a workshop corner. Now that I'm getting ready to finish the basement, I plan to include the work/rework on these circuits as a part of my permit and get it inspected.

The initial meeting with the inspector to learn some basics (how to get a permit, what work can I do as a DIY), I discussed my problematic sub-panel. But our meeting was cut short before I got an opportunity to ask about the j-boxs.

Basically, I have 10/2 on a 20 amp circuit and 12/2 on a 14 amp circuit running parallel to each other along the rim joist. When I reached a point where I wanted to install some power outlets on the cinder block wall, I had the NM cable enter a j-box, tie into some THHN running down 3/4" conduit to a pair of outlets, and then out the j-box on along the rim joist.

When I did this, I didn't know about fill limits nor having wires extend past the face of the j-box. What the means was that I was faced with finding a way to put 12 LARGE conductors and 5 grounds in a standard size 4x4 jbox.

My solution was a very neat arrangement of 5 wire nuts with each and every wire cut to the precise lenght to reach its assigned wire nut. (Boy was I nervous striping those wires as a single mistake ment I had to rerun the entire sheath from the previous jbox).

In the end, I wound up with a very neat looking set of connections in the jbox, and the wires actually do not fill the box. I was rather suprized as just how much space there is inside the boxes when I removed one of these covers to take a picture to show the inspector. (When I get home tonight, I'll try to dig out that picture and post it here).

Because I am using over sized conductors for the circuits (so I don't expect much heating), and it's only two circuits (so the wires don't look like spagetti), and there is still lots of room in the box, I don't believe there is any safety issues. But it all still a code violation in terms of wire lengths and fill count.

Given that this is old work and it's in an exposed area of a garage, when I show it to the inspector, do you think he will let me keep it? Or is this such a bad violation, I shouldn't even bother asking and just spend the hours it will require to both rip it out and re-run all the wires with all new jboxes?

Advice Wanted!


Last edited by HooKooDooKu; 01-29-2010 at 03:58 PM.
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Old 01-29-2010, 04:53 PM   #2
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Short Wires in an Overfill


the fact you trimmed wires removed it from being considered "old work"

exactly what size of box is it and how many wires of what size do you have in it.


a wire that has an end in the box is 1 wire (if you have a wire that comes in and simple makes a joint and then goes on to somewhere else, that counts as 2). a wire that passes through without being cut or joined in the box is 1 wire.

what is the largest ground wire?

is there any devices in this box and how many and are there any NM clamps internal?

If there is a device, what kind of plate is it mounted on (such as a raised cover or what)

and if the box is over filled, is there any problem with using something like this:


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Old 01-29-2010, 05:34 PM   #3
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Short Wires in an Overfill


The description I provided is how I originally installed it. It was the only way to physically allow three sets of 10/2 AND three sets of 12/2 to all be connected in a single 4x4 box.

I seem to recall it's an "average" size 4x4 box (NOT an "extra deep box like I got for that J-B Weld job where I'll have "ONLY" 10 concuctors").

The largest ground is the #10 AWG coming in from the 10/2 NM cable.

No internal clamps, I seem to recall putting external clamps through the knockouts to hold the NM. There's no device for the J boxes I'm talking about here. This is just the box used to tie some conduit into the NM cable, with the conduit feeding a pair of outlets. As a seperate question, I would need to chech the fill of the 4x4 box holding the outlets. Let's see, that one would be 4 conductors, ground, two devices, so 9 conductors counting toward fill, with the largest conductor being 10 AWG. Again, the box is a "standard" depth 4x4 j-box. The outlets in these boxes are covered with "typical" twin duplex reciptical covers (so I guess that would be "raised").

I can't see the picture you are showing (is blocked at my current location). I can only assume you're trying to show a j-box extension that would make the box deeper. If I'm right, adding something like that would seem like a waste. The wires, because they were "cut-to-fit" to begin with, couldn't be moved to use the space, and the box will forever remain exposed (maybe behind some drop ceiling in the future, but given this is a garage, even that is unlikely).

For sure, the box is over full. I don't think its deeper than 2", so that's 32cu.in. I've got 12 conductors plus ground, with the largest conductor being #10. That means I need a box that is 13 * 2.5 cu.in. or 32.5 cu.in. Looking at the Lowe's web site, I THINK I have the 21 cu.in. square box.

I post an update with pics sometime tonight.
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Old 01-29-2010, 06:11 PM   #4
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Short Wires in an Overfill


in 4" boxes, you generally have shallow (1 1/2" deep) and deep (2 1/8" deep) as more or less standard or common.

and yes, the pic is an extension ring. while the wires may be too short, it does provide an additional 21 c.i of volume. you would still only be required to have 6" of free length on the wire in the box. and if it actually helps or not is less relevant that if it causes the installation to meet code.

the only largest conductor is relevant is for the EGC. in the others, each wire is used based on it's actual size.

#10 is 2.5"
#12 is 2.25"
#14 is 2.0"

egc's count as 1 of the largest wire (in the egc group)
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Old 01-29-2010, 08:15 PM   #5
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Short Wires in an Overfill


Here's the pic I promissed... as you can see, I don't have 6" free except for wires that cross the box.
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Old 01-29-2010, 09:17 PM   #6
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Short Wires in an Overfill


The 6" of free conductor is from the back of the box. You also need to have 3" out past the front face of the box.

The NEC value for a 4x4x1 1/2" deep box is 21 cubic inches, unless stamped otherwise.
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Old 01-29-2010, 09:36 PM   #7
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Short Wires in an Overfill


I would not bother the inspector with this one.
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Old 01-29-2010, 09:49 PM   #8
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Short Wires in an Overfill


(3) 12-2's & (3) 10-2's

(6 * 2.25) + (6 * 2.5) + 2.5 ground

13.5 + 15 + 2.5 = 31 cu for box fill.... ?

But....looks like plenty of room
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Old 01-29-2010, 10:01 PM   #9
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Short Wires in an Overfill


actually

4 12's
4 10's

plus 1 10 for the egc /all egc's count as 1 of the largest egc in the box

21.5 cu in.

if the conductors were proper length, it would look a lot more full but I would not worry about that install as it is.

whoops, ignore that. I needed to put on my glasses.


lets go with dave's

Last edited by nap; 01-29-2010 at 10:12 PM.
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Old 01-29-2010, 10:12 PM   #10
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Short Wires in an Overfill


Quote:
Originally Posted by nap View Post
actually

4 12's
4 10's

plus 1 10 for the egc /all egc's count as 1 of the largest egc in the box

21.5 cu in.

if the conductors were proper length, it would look a lot more full but I would not worry about that install as it is.
He has 3 sets of each - 2 of each via the cables, then the conduit
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Old 01-29-2010, 10:18 PM   #11
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Short Wires in an Overfill


Quote:
Originally Posted by Scuba_Dave View Post
He has 3 sets of each - 2 of each via the cables, then the conduit
glasses, I needed my glasses.

still not 100% on the count. It looks like 10 #12's, 2 #10's plus 1 #10 for egc's

that would come out to 30 ci I believe. Like I said, if the conductors were full length, it would be more full.

while a violation due to the overfill (by calc's, it actually looks fine) and the conductors, the wires are not so short as to cause then to be pulled against each other and as stated, due to that, they really are not crowded.



ETA: I give up!!!!!!!!!!!!!
hooku, give me a dang count. every time I look at it, I can't decide what is 10 and what is 12.
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Old 01-29-2010, 10:22 PM   #12
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Short Wires in an Overfill


Quote:
Originally Posted by Jim Port View Post
The 6" of free conductor is from the back of the box. You also need to have 3" out past the front face of the box.

The NEC value for a 4x4x1 1/2" deep box is 21 cubic inches, unless stamped otherwise.
actually the 6" is from where it exits it's sheath or conduit but nearly the same as to the back of the box.
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Old 01-29-2010, 10:23 PM   #13
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Short Wires in an Overfill


and hooku, why did you mount that with a spacer behind the box? No bender?
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Old 01-29-2010, 10:28 PM   #14
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Short Wires in an Overfill


Quote:
Originally Posted by HooKooDooKu View Post
It was the only way to physically allow three sets of 10/2 AND three sets of 12/2 to all be connected in a single 4x4 box.

I seem to recall it's an "average" size 4x4 box (NOT an "extra deep box like I got for that J-B Weld job where I'll have "ONLY" 10 concuctors").

The largest ground is the #10 AWG coming in from the 10/2 NM cable
I was going by what he posted, I only counted the cables 1st time around too
I have my monitor to display at 125%, I bump it up to 150% every now & then to look at pics
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Old 01-29-2010, 10:33 PM   #15
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Short Wires in an Overfill


with that I come up with using that is 31 c.i

6 x 2.5 (the 10's)= 15.0

6 x 2.25 (the 12's)= 13.5

1 x 2.5 (the egc's)= 2.5

---------edit------------

Quote:
(3) 12-2's & (3) 10-2's

(6 * 2.25) + (6 * 2.5) + 2.5 ground

13.5 + 15 + 2.5 = 29 cu for box fill.... ?
.

I don't feel so bad now.

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