Extension Rings/Box Fill Question

Are box extensions acceptable/safe alternative to having to rewire/remove wire from an overfilled box?

In my case I have a 4x1.5" Octagon box that is overfilled. How many conductors and cubic inches are there to be gained by adding an extension in my case?

BTW: I am not trying to get around a code enforcer, I am looking to make existing installation safer....

 

It would depend on the depth of the extension ring. There isn't just one size.

 

The number of conductors allowable in a box depends on the size of the conductors, whether ther are terminated, spliced or pulled through the box, and the number of other things that require space, like devices and internal clamps. You need to first calculate the space you need and then choose the enclosure that will meet that need. To answer your other question,

Yes.

Your existing box has a rated capacity of 15.5 in.[SUP]3[/SUP]. A 1-1/4" extension ring will add 12.5 in.[SUP]3[/SUP]; a 1-1/2" ring will add 15.5 in.[SUP]3[/SUP], of course, and a 2-1/8" ring will add 21.5 in.[SUP]3[/SUP].

 

When you use an extension ring are you supposed to spread the wiring out to fill it up or just pop it on there?

I dont like to distrub old wiring insulation unless I have too.....

 

You can arrange the wiring inside a box any way you want to.

Is the old insulation brittle and likely to flake off and leave the conductor exposed? If so, you need to use Liquid Tape, heat shrink or a good quality electrical tape to repair the insulation, rather than just leaving it alone and hoping for the best.

 

I just left them be but how is the extension ring anymore safe for an overfilled box if the wires are still compacted into the undersized box?

One of the two boxes I put an extension on the wirenuts were pushing onthe cover, now they naturally spring into the extension. However, the one that was even more overfilled, the wires were compact enough under the cover that there was no movement with the extension.......

so where is the breathing room?

Could of used the 2 1/8 deep octagon but the big box stores in my area doesnt carry that big ones... gotta get it at a supply house I guess.


Not needed. However, I always thought the real fix to flaked insulation is new wire. Arent your suggestions just band aides? Are they meant for the long term? I know that liquid tape stuff you suggest isnt UL approved.

 

Yes.... the real fix is to replace the wire however that is rarely practical.
Are you prepared to open your walls to start replacing wiring ?

 

I didnt think of that, your correct. Maybe I should have asked, are any of those code compliant fixes?

Im guessing shrink tube yes, electrical tape maybe and definetly not for liquid tape.

 

Wires don't need to breathe. What's needed is enough room to allow the heat to be dissipated enough to prevent damaging the insulation on the wires.

Not every product needs to be U.L. Listed, although it is preferable. One of my specialties is upgrading and repairing the wiring in historic structures, and I've used these products for repairs that have lasted for years and are still going strong.

BTW, I just found a new product from GB that looks very interesting for this work. They call it Repair Tape.

 

Are the extension rings supposed to snug right up against the old box?

The ones I put into place yesterday dont match up quite perfect, there is still like a 1/8 to 1/2" gap on some of the sides.... THe old boxes are ancient, so I am assuming an exact match wouldnt be possible??

 

The extension ring should fit tightly to the original box.

Can you post a picture? Box sizes have been standard sizes for many years.

 

Maybe the screw hole tabs on the old one are bent or misaligned. I will try to remount them on the other 2 holes and see if that makes a difference.

Sorry no photo....