Conductor insulation damage

[Little Bill]

I’m surprised no one has cited Section 110.12. It may seem to be a bit ambiguous but the IN references a very specific standard.

I started to put that in but I didn't.

 

[jmellc]

The cables shown in the OP's picturess were damaged because they weren't stripped prior to inserting them into the boxes. I only do that with cables fished in during remodel work.

Back when I was a helper, I was taught to pinch the sheath in two or three places around the cable with the corner of my pliers, creating holes and cuts, then sliding it off of the wires.

I was taught to strip first too, but with plastic boxes & punch ko’s, it is hard to do without the jacket snagging the snug ko. A flat 2 wire cable is easy to strip by starting at the end, 2-3 inches up. Pull out the ground wire & use as a string to split jacket back and cut off. 3 wire round cable won’t do this, plus the twist makes it hard to find a “groove” to follow. I usually do same at the end, then try to pull & split jacket back. If jacket is too tough, I carefully go in & score it long way a few times til it will split. I dislike twisted cable for that reason.

Klein used to make a cable knife that was good for this. I had one & couldn’t get another when I lost it. I’ll see if I can find a pic.

 

[hbiss]

Klein used to make a cable knife that was good for this. I had one & couldn’t get another when I lost it. I’ll see if I can find a pic.

The "hawk billed" knife? That's what I use. I never advised using a box cutter or razor knife. Too sharp and too easy to do damage.

As to the OP, I think the whole problem here is cheap, poorly trained labor and a contractor pinching pennies.

How many times have we told guys starting out and considering working for tract builders that they will never make any money.

-Hal

 

[Little Bill]

I use these and I cut/score the NM before putting it the box, but I don't pull off the sheath until it's in the box.

 

[electrofelon]

I don't think there is any one correct way. Either way can go awry.... I've seen those NM sheath strippers damage cable too.

 

[Little Bill]

I don't think there is any one correct way. Either way can go awry.... I've seen those NM sheath strippers damage cable too.

Usually operator error!

 

[mtnelect]

I always strip with a knife, after the cable is in the box. It really isn't that hard to not damage the cable

I also use a utility knife and lightly score around the cable, then insert into the enclosure. Then just pull on the outside sheath to separate it from the cable.

 

[electrofelon]

I also use a utility knife and lightly score around the cable, then insert into the enclosure. Then just pull on the outside sheath to separate it from the cable.

I insert in box first, score sheath starting just below the clamp or entry slicing all the way through the last few inches because it gets cut off anyway, rip sheath off the inners, cut off with knife just below the clamp/entry. I am very fast and never cut the insulation.

 

[jap]

No, look again.

Ooops my bad,, one could only hope.

JAP>

 

[jap]

For the moment, until box gets reworked down the road. Then you may have fireworks.

Only if you fail to shut the circuit off first.

Undisturbed and it is unlikely to ever cause a problem.

I've seen receptacle and switch terminals very close to metal boxes that were more likely to cause fireworks before nicked conductor insulation as in the picture ever would.

Regardless, this needs to be corrected before the sheetrock goes up.

JAP>

 

[kwired]

I always strip with a knife, after the cable is in the box. It really isn't that hard to not damage the cable

me to. and often not until trim out

 

[kwired]

Only if you fail to shut the circuit off first.

Undisturbed and it is unlikely to ever cause a problem.

I've seen receptacle and switch terminals very close to metal boxes that were more likely to cause fireworks before nicked conductor insulation as in the picture ever would.

Regardless, this needs to be corrected before the sheetrock goes up.

JAP>

I agree, I also agree with Larry in not making an additional connection to fix this. Tape, liquid tape, shrink tube all work, even just a little dab of silicone caulk would work in a pinch though it wouldn't be recognized as something listed for the application.

 

[jap]

I insert in box first, score sheath starting just below the clamp or entry slicing all the way through the last few inches because it gets cut off anyway, rip sheath off the inners, cut off with knife just below the clamp/entry. I am very fast and never cut the insulation.

I'm in the group that inserts it into the box first also, but, differ in the fact that I also use my hook billed knife and follow the ground wire down the center to the end.

Never had an issue doing it that way,

I'm not a resi guy, but, got put on an apartment jobsite once for a couple of days when we were slow on the industrial side where they scored "across" with a razor knife, and, it did go too deep and slit the insulation across the conductors.

I noticed it immediately. They were super fast, and actually called me out for being too slow in the way that I was doing it.

Until it got caught by the inspector that is.

They ended up having to replace every damaged cables prior to the sheetrock being installed.

JAP>

 

[jmellc]

The "hawk billed" knife? That's what I use. I never advised using a box cutter or razor knife. Too sharp and too easy to do damage.

As to the OP, I think the whole problem here is cheap, poorly trained labor and a contractor pinching pennies.

How many times have we told guys starting out and considering working for tract builders that they will never make any money.

-Hal

No it wasn’t a Hawk bill. Had a blunt tip to insert from end, then it guided the sharp blade Ii into jacket, cutting from inside to outside.

 

[SterTheDer]

No it wasn’t a Hawk bill. Had a blunt tip to insert from end, then it guided the sharp blade Ii into jacket, cutting from inside to outside.

Sounds like the Knipex 98 55? Seems like a handy thing to have, i may have to obtain a knockoff one for $20. 1000V insulated, so you can... cut and splice live conductors I suppose. (Thats a no from me dog)

 

[jmellc]

Sounds like the Knipex 98 55? Seems like a handy thing to have, i may have to obtain a knockoff one for $20. 1000V insulated, so you can... cut and splice live conductors I suppose. (Thats a no from me dog)
View attachment 2564438

Nothing close to this but this does look good. Never saw it before.

 

[hbiss]

I'm in the group that inserts it into the box first also, but, differ in the fact that I also use my hook billed knife and follow the ground wire down the center to the end.

That's what I do.

-Hal

 

[jmellc]

I'm in the group that inserts it into the box first also, but, differ in the fact that I also use my hook billed knife and follow the ground wire down the center to the end.

Not too hard to do with flat 2 wire NM but 14-3 or 12-3 is a different story. I hate the twisting, makes it hard to find a clean path. I'd like to see all NM with wires laid straight.

 

[tthh]

Kinda like the flat 14-3/12-3

 

[zooby]

The "hawk billed" knife? That's what I use. I never advised using a box cutter or razor knife. Too sharp and too easy to do damage.

As to the OP, I think the whole problem here is cheap, poorly trained labor and a contractor pinching pennies.

How many times have we told guys starting out and considering working for tract builders that they will never make any money.

-Hal

my lead man( circa 1988) took my brand new hawk billed and dulled it down real nice. he explained what was what and i was conscientious of that ever after. we always stripped before the placing in the box.