[Rolin]

I was installing baseboard in my basement with a 16 gauge finish nailer and must have hit a wire in some flex conduit in the wall - the breaker (newer arc fault type) blew. I removed the nail, reset the breaker and seems to be OK.

I know this isn't a good thing, but hoping my fears are wrong. Do I need to open up the wall and repair, or is there any chance this can be left alone. Again, this is Flex Conduit with a newer arc fault breaker type. If I do need to repair, what is the best way to handle it.

BTW: I know there will be questions how this could have happened. Previous owner installed romex in shallow walls near the bottom. I'm remodeling the basement, I decided to replace the romex with flex conduit because I thought it would protect against nails! Guess I was wrong!:sad:

 

[chetwisner]

If it were me, I'd wanna know. Take out just enough to see the wire really well, and take a pic and upload it here.

 

[Wiredindallas]

I would suggest replacing the wire. Just knowing there is damaged wire would worry me.

 

[de-nagorg]

Bite the bullet, and repair / replace this NOW, you will sleep better knowing that you prevented a possible housefire.


ED

 

[seharper]

If you really think it's constructive to see the problem without repairing the problem, then borescopes are getting pretty cheap.

Were you using very long finish nails? Why? Or was the flex conduit quite close to the wall? Any wire within 1.75?? inches of a finished wall surface is supposed to have a metal guard on it, specifically to stop this from happening. If you use excessively long nails, that's on you Otherwise, it's on the installer of the conduit!

If you need conduit that is its own metal guard, that's EMT.

 

[Rolin]

Thanks for the replies. I should be more clear on my question. This is Flex Conduit, not Romex - so I can't see the damage unless I open the conduit in that spot.

This is a shallow wall in the basement. I'm remodeling, so I replaced the orig Romex (installed by previous owner) with Flex Conduit because I thought it would be safer when nailing - found out I'm wrong. Maybe I shouldn't use the nailer and manually nail instead?

I understand it'll need to be repaired for peace of mind. There isn't enough conduit length to place a box or additional outlet in that spot.

Is there a way to open the wall in that spot, remove the conduit around the damage wire (without cutting the wire) , tape the damaged wire, then repair the conduit with some kind of Flex Conduit coupler/housing/cover or something? Otherwise I have to cut a large section of wall to replace the entire run!

 

[MTN REMODEL LLC]

ROLIN.....I'm not sure what you mean by flex....is it bxx/mc/liquidtight.....

Can you not just pull new wire from recep to recep or whatever your shortest run is between where you "nailed it".

 

[de-nagorg]

Is there a way to open the wall in that spot, remove the conduit around the damage wire (without cutting the wire) , tape the damaged wire, then repair the conduit with some kind of Flex Conduit coupler/housing/cover or something? Otherwise I have to cut a large section of wall to replace the entire run!

This in itself is classified as a junction.

And only allowed if you install a junction box with accessible lid.

ED

 

[daveb1]

Taping the damaged conductor would only be an acceptable repair if there is only damage to the insulation, and no damage to the conductor itself. Possibly more work to do an inspection and still have to replace. Go with replacement from the start.

The type of nailer or nailing method makes no difference, it's using too long a nail that caused the problem.

 

[Jim Port]

Nail pilates are needed within 1.25 inches of the surface, not 1.75.

 

[Rolin]

This in itself is classified as a junction.

And only allowed if you install a junction box with accessible lid.

ED

I understand this. Based on some research, if a nail hits Romex and just damages the insulation - I've read simply taping the damaged insulation can be a solution (has passed inspection based on several posts). I'm wondering if I can remove some of the conduit (WITHOUT CUTTING THE WIRES), tape the damaged insulation (if the conductor isn't damaged) and put some kind of clamp type coupler over it. Again, this is a major project to rerun from outlet to outlet - I know you can't see this project, but this is not a standard setup (regretfully) on shallow walls. Too much to describe... (including a built in cabinet in the way)

 

[Rolin]

ROLIN.....I'm not sure what you mean by flex....is it bxx/mc/liquidtight.....

Can you not just pull new wire from recep to recep or whatever your shortest run is between where you "nailed it".

This is 3/8 MC Flexible Conduit like this https://www.homedepot.com/p/Southwi...Metal-Clad-Armorlite-Cable-68579221/202316372

I've never pulled wire through this - seems very tight. The problem is there are some very tight bends (especially around a tight corner in this shallow wall) that could create a challenge and possibly a mess if I cant pull through. Also, is there a concern a sharp point inside the MC where the nail hit? Could this also create problems scraping the wire when pulled through?

 

[oldelectricguy]

It appears the you want someone here to tell you it's OK to do something that's not OK (tape the wire inside the wall). The only code compliant and acceptable solutions IMHO are to open up the wall, install a junction box (always accessible) at the repair site and do the repair properly, or re-pull new wires/cable.

 

[Rolin]

It appears the you want someone here to tell you it's OK to do something that's not OK (tape the wire inside the wall). The only code compliant and acceptable solutions IMHO are to open up the wall, install a junction box (always accessible) at the repair site and do the repair properly, or re-pull new wires/cable.

Sorry if I'm coming off that way. I was sharing what I read from other posts that passed inspection. Also, I have no problem running wire through this 3/8 inch flex conduit if I was confident I could do it without creating a mess if it fails - where I have to pull out a lot of sheetrock and built-in cabinet in the way to replace the entire run. As far as a junction box, I know you can't see the situation, but the wire is low on the wall (reason I hit it) - there's not enough conduit to pull up to the proper position for a junction box or add an outlet. In the end I'll do what I have to do, but right now looking for options from more intelligent minds than mine on this subject:wink2:

 

[de-nagorg]

Install the junction box oriented HORIZONTAL, not vertical.

Should be enough room to do it this way.


ED

 

[Jim Port]

MC cable cannot have the conductors pulled out and replaced.

 

[Rolin]

I did open the wall and removed about 1" of the MC around the nail hole and inspected the wires. The White wire insulation was nicked, but the conductor looks OK. The Black and Green wire looks OK. I did place tape around the White wire (and Black wire to be safe). I placed a couple of antishock bushings on both sides - now just trying to see if I can customize a way to cover it with some sort of metal clamp housing. I know this is not by the book, but I don't think the book covers every scenario. I'm trying to find a reasonable and balanced repair that is SAFE - since the wires looks OK except for a nick in the insulation it seems worth a shot.

But... I understand the other option is to mount a box (to add an outlet) to the left of the nail hole to get enough slack in the flex MC, then remove the sheetrock all the way to the next outlet to rerun new Flex MC. I know this is probably the best and preferred method for my problem - a small nick in the insulation of the white wire! Wish a simpler solution was available!

 

[Old Thomas]

NEC Section 300.4(A)(1) Bored Holes says that the hole bored through framing members for wires shall have the edge of the hole no closer than 1 1/4” from the edge of the framing without protection from damage. The dimension is not from the finished wall and it is not from the wire, it is from the edge of the hole the wire passes through to the face of the framing member.

 

[betelgeuse]

3/8" Flex and MC Cable are 2 different things.
As Jim said, you can't replace the wires in MC, whereas flex you can.
The rules against physical damage are exactly the same as NM (Romex) for both of them.

 

[seharper]

I'm wondering if I can remove some of the conduit (WITHOUT CUTTING THE WIRES), tape the damaged insulation (if the conductor isn't damaged) and put some kind of clamp type coupler over it

I think you're missing the point of how conduit works. Conduit is supposed to connect the junction boxes. And after you're done laying conduit, you pull the wires you want through the conduit. And if you don't like the wires later, you can pull them out of the conduit and stick new wires in, without having to mess with the wall finish in any way. Slick system actually, very convenient to change later.

So this should be as simple as go to the junction box on either side of the damage point, pull the wires out between them (remembering to leave yourself 6-9" of length for splicing), and then replace the wires. If you ran cable in conduit (not illegal, just the hard way), you can replace with individual THHN wires.

Now, if you did something wackadoodle where you ran cables like cables and just threw the conduit as a sleeve over the cables intending that to be your damage guard, well, you picked the wrong stuff sorry. However this might still be saveable.

Another option is to put junction box extensions on the 2 junction boxes in question, and run the replacement wires in surface conduit, and just abandon the in-wall cable.