The wires don't appreciate me! (Box too small)

slateberry51January 9, 2011

OK I've heard about how brutal this forum is. I've read a few posts and mostly found things to be very interesting and informative--maybe my skin is just thicker than some. Anyways, I've been forwarned so don't hold back--I've got my body armor and a full bottle of JD for comfort at the ready. Let's have some fun with this!

I've been slowly replacing the light switches in my house with classic accents push button switches. Normally it is a simple process: turn off power to circuit, remove cover plate, test to confirm power is off, disconnect old switch, wire in new switch.

This time I was replacing a 4 pole switch. I opened up the tiny single gang box, and what a mess! 5 cables coming in, total of 11 wires plus grounds, 2 of them romex, the other 3 bx. 3 wire nut junctions. I couldn't believe it was all packed into a tiny single-gang box with a big 4 way switch, and the switch I wanted to put in was another 1/4" deeper than the original.

I just wonder what the pros do when they encounter a mess like this. I had several thoughts:

-how can I get a bigger box here to make it all fit (no problem, I replaced it with a double-gang, I used metal and all the bx is still properly grounded)

-aren't there rules about how many junctions of various gauges allowed in so many cubic inches, and how could this possibly have been code?

-To address the excessive junctions in what is after all just a switch box, do I pull new, longer wires to replace the old ones, and run them down into a junction box in the basement (only 5' away)? Or do I just close my eyes and screw the switch plate back on?

Oh, and do the wires appreciate all that new space I gave them? Nope! It was still a painful wrestle to fit it all in and get the cover on ,even with twice the real estate. Sometimes I think I'm just too generous with those wires.

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"-aren't there rules about how many junctions of various gauges allowed in so many cubic inches, and how could this possibly have been code?"

There are box fill rules, but they do not count pigtails that are used in a box with multiple devices, and it can still get pretty crowded.

If the wires are #12 for a 20 amp circuit the extra stiffness can also make getting everything in (even within the fill rules) a chore.

One common way is to use 4x4 boxes with a plaster ring to single or double gang.

The extra space comes in handy, even if it is hard to push wires into the edges from a smaller plaster ring.

If all the wires area sinlge size it is easier to determine the fill count.

-All the grounds count as one conductor.
-Each device yoke count as two conductors
-Internal box clamps count as one conductor
-Each conductor that originates outside the box and is spliced or terminates counts as one conductor.

If there is more than one wire size present you have to compute the cubic inch fill for each conductor in the count instead of just counting wires.

314.16(B) covers fill allowances, and Table 314.16(A) gives the volumes of standard boxes.

Table 314.16(B) gives the volume allowances assigned to different wire sizes.

Inspectors often do not check carefully for box fill violations.

They have a very limited time on each inspection and all sorts of stuff slips through.

Add to that the number of homeowners that simply tap into the nearest box to extend a circuit (adding at least two more conductors) and violations of fill are pretty common.

You should get the NEC sections above and actually see if there is a fill violation.

Some drywall repair for a larger box is often the easiest fix.
Pulling additional lines can easily result in more drywall damage than just enlarging a single box.

    Bookmark   January 9, 2011 at 4:00PM
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The old switch probably was a 4-way. That is a variation of a double-pole, double throw. One solution is to use a surface extension, such as Wiremold. Available in various depths. Not necessarily the most attractive solution. If you decide to replace the existing box, look at the possibility of cutting into the wall behind the box. Will that side be easier to patch?

Here is a link that might be useful: Wiremold

    Bookmark   January 10, 2011 at 6:54PM
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Wire mold just looks like hell.

I have to use it in SCIF exterior walls since no wiring of any kind is allowed inside the walls, and it still looks bad.

    Bookmark   January 11, 2011 at 12:03PM
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Hey brick, nice to see you over here and thanks for the great advice. I had gotten a plaster ring so it was good to know I was on the right track. It seemed to me to make sense to enlarge the box, but I always wonder if a pro would hit me over the head with linesman's pliers and call me a dufus every time I try to "innovate" like that! yes, I know when in doubt call a pro, but for a switch replacement I really wanted to go it on my own.

I'm still working on those NEC tables; I found one online with a free one-day trial so I'm going to wait until I open up another problematic box and look everything up at once while I've got the free trial.

Bus driver, thanks for the tip about the wire mold. Since I got the bigger box in I'll stick with that, but it's nice to know it exists. Another one for the bag of tricks.

I did not appreciate running into this problem at all; the power to the circuit had to be left off for hours while I ran around getting more boxes and tools. If I were a pro working on a fixed-price job, I'd be cheesed at losing money because something took so much longer than expected. On the other hand a pro would be prepared for the contingency and it would have gone from a 15 minute job to a 30 minute job. For me, it went from minutes to hours. But I'm sure it's not the last time I run into this problem, so I'm glad I've got it figured out.

Thanks all, great forum. Really liked the thread about the guy running power out to his shed--now THAT is definitely a job I would not tackle on my own. But I am going to look at how the power is run out to my garage. I bet it was a hack job and will need to be replaced. We are slowly replacing a lot of the wiring in this old house. (Don't even ask me about how the attic fan was wired, scary!) But at least we had no K&T. And we've got arc faults on all the bedroom circuits, so I sleep a little better at night.

    Bookmark   January 11, 2011 at 3:53PM
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This is one area where I would consider using the plastic push in connectors since the wires can rotate in them. It 'seems' like you would be given some added flexibility and have an easier time getting everything to stay in place better. If your not up to par on the wire nutting this method might be better in the long run.

I know I know.. wire nuts are unbeatable if the wire is twisted good and trimmed to the proper length and the right size nut is used. If the wires are just shoved in for three twists and then poked prodded and jammed into the box its a recipe for a mess.

    Bookmark   January 13, 2011 at 12:20AM
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There are older code copies that can often be viewed for free (though you may need to register) an the National Fire Protection Association.

The box fill table has not changed in many years.

    Bookmark   January 13, 2011 at 2:06PM
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