house electrical wiring problem

Here goes...

While builing some shelves into the wall of my home office, I accidentally shot a nail from my nail gun into some wires in the wall. The nail was a 3.5" finish nail of either 16 or 18 gauge.

I fired off about 10 nails quickly, and am not sure which nail is the problem. Right after I fired the nails, I noticed the lights go "blip". I ignored it, and later found that the breaker for clothes dryer #2 had flipped.

The problem is that I would love to try and fix this w/o tearing into the wall. The wall in question is an exterior wall. It is layered like this: brick/insulation board/stud wall with blown-in insulation/sheetrock/paint/1" thick end support for my shelves.

To further complicate matters, this section of wall (between 2 studs) contains: the other dryer wire, the kitchen cooktop wire AND a 2" plastic conduit that contains the main feed from the outside panel to the inside panel. Oh yeah, the outside panel sits on the exact opposite of the wall from the area in question.

What I have done:
1. left the breaker off and ignored the problem for 8 months
2. got motivated and decided to fix this

I pulled the outside breaker out of the panel so I could test and try to find exactly what the nail shorted out.

Before I go further, I am assuming 1 or more of the following:
1. the nail shorted between both hot wires for dryer#2
2. shorted between either/both hots and the neutral wire
3. shorted from dryer#2 hot(s) and another hot/neutral wire from the cooktop
4. NOT assuming that the dryer#2 wire shorted to anything in the 2" conduit. This is because they are close (in the same stud space) but not close enough together.

I could find no voltage on dryer#2, indicating that the hot wires were not shorted with hot wires from another appliance. Also, if say dryer#2 hot1 shorted with dryer#1 hot2 (out of phase) then wouldn't have the breakers flipped for both circuits?

I could find no continuity on dryer#2's hot wires and ground, indicating that they were not shorted to a ground or a neutral wire.

I applied a small dc voltage to the wires and used my probe to check the nail heads for voltage. None was found.

I reinstalled everything and turned the breaker on; it did not trip again. I did not apply a load though. This leads me to think that the nail:
1. grazed some wires and then moved away from them
2. being a small nail, it was burned in half and opened the circuit (right as the breaker tripped). This does not seem likely since none of the nail heads showed voltage in my test and they did not show continuity with ground either.

Ideas? (other than tear the wall out?)

electricity is not something to mess with if it was me id tear down wall and visaly inpect.

It has been suggested by an electrician that I get in the attic, clip the wire where it comes up from the exterior wall, and run this wire to the inside panel. Inside panel has enough ampacity, but I would have to install a "double" breaker for 2 of my 110 circuits. This is an option I'd rather not explore.

I don't know exacally what you have. But you might can cut the wire up top. get enough new wire to refeed the panel.Go to Home depot and buy you a cutin box (old work).Cut it in the wall between the panel and the cieling, that will let you get your hand the wall to feed the new wire from the ceiling to the main panel. Mount you a box in the ceiling to make joints on the new and old wires. When you are done install your cut in box with a blank cover. Hope this helps.
Make sure everything is grounded and you turn the power off before you start.
Trent

There are several options to fix/patch it. I'm trying to figure out what happened at this point without tearing into the wall. My main concern is if it caused other damage. Replacing/bypassing dryer#2 does no good if the other wires are seriously nicked or damaged.

Why, oh why were you not using a stud finder (would have found Darrell!) and using studs for where you were nailing dude?

I agree with Raggie. You almost HAVE to open the wall. Otherwise take ALL the existing wires out of play, and run "new" boxes and wires.

Short circuits, inside walls, AIN'T nothing to fool around with!!!

Like Playboy Joe Shmoe indicated, major fire hazard unless you take all the wiring that you might have damaged out of the equation. If it were me, I'd do the raggie thing or what the electrician recommended. But for sure make all of those wires "cold".


Mike

[ QUOTE ]
PlayboyJoeShmoe said:
Why, oh why were you not using a stud finder (would have found Darrell!) and using studs for where you were nailing dude?

I agree with Raggie. You almost HAVE to open the wall. Otherwise take ALL the existing wires out of play, and run "new" boxes and wires.

Short circuits, inside walls, AIN'T nothing to fool around with!!!

[/ QUOTE ]

Hmmm, I just had an idea.

Even IF I tear into the wall (from the inside of course), it will be a pain to repair/re-run the affected wires. But, as we all know, w/o opening the wall you don't know what is affected. But, if I pull all 3 runs (dryer #1 and #2 and cooktop) then I'm basically assured that I'm ok.

With the outside panel right there, I could run a new feeder wire up the side of the brick, through the soffit, and into the attic. Then I could simply put a small breaker panel there and feed the 3 appliances from that panel. And it wouldn't be TOO hard (all things considered) to run this conduit/wire/etc.

???

Can you pull them one at a time?? You might get lucky right off the batt, start with the wires for dryer 2 if that was the one that threw a breaker tie off on it so you can pull back any undamaged ones? O.K. I am not a electrical engineer just guessing.
Topper /ubbthreads/images/graemlins/smile.gif

[ QUOTE ]
PlayboyJoeShmoe said:
Why, oh why were you not using a stud finder (would have found Darrell!) and using studs for where you were nailing dude?

I agree with Raggie. You almost HAVE to open the wall. Otherwise take ALL the existing wires out of play, and run "new" boxes and wires.

Short circuits, inside walls, AIN'T nothing to fool around with!!!

[/ QUOTE ]

Stud finder...

I knew these wires were at that point behind the end of the set of shelves. The wires were from waist-high to the ceiling. I shot nails into the bottom half of the shelf support, got to talking to someone, looked back at the shelves, said "why are there no nails here?", and fired away. As far as studs go, the shelves are 12" deep and happen to hit in a stud space, so nothing to nail to. The back of the shelves are supported by 1"x2" strips of wood beneath each shelf. The nails through the end are simply because the nail gun is fun to use.

Installing a whole new main run panel is not a big deal?

I would think that the only solution worth pursuing is to re-run the affected wires. even if you did tear into the wall you'd find the nicked/burnt wire, but you can't just "spilce" something in there, you'd need to cut it and put in another piece which is a real pain on heavy gage wire and you'll end up with a box in the wall under your shelves.

I'd re-pull the wires for those things you know are in there.

But, tearing a hole in the wall would tell you exactly which wire was nicked and maybe make it easier to pull the other through. If it were me I'd make a hole AND pull a new wire, but that way I'd only have to pull 1 new wire.

Don't pull a new feed from the meter unless you have to as you have to call the electric company to pull the meter anyway there don't you? I know I'm not allowed to pull my own meter, the electric company would get very angry at me.

[ QUOTE ]
James S said:
Installing a whole new main run panel is not a big deal?

I would think that the only solution worth pursuing is to re-run the affected wires. even if you did tear into the wall you'd find the nicked/burnt wire, but you can't just "spilce" something in there, you'd need to cut it and put in another piece which is a real pain on heavy gage wire and you'll end up with a box in the wall under your shelves.

I'd re-pull the wires for those things you know are in there.

But, tearing a hole in the wall would tell you exactly which wire was nicked and maybe make it easier to pull the other through. If it were me I'd make a hole AND pull a new wire, but that way I'd only have to pull 1 new wire.

Don't pull a new feed from the meter unless you have to as you have to call the electric company to pull the meter anyway there don't you? I know I'm not allowed to pull my own meter, the electric company would get very angry at me.

[/ QUOTE ]

No....

Outside meter feeds:
30A dryer#1
30A dryer#2
30A cooktop
50A hvac outside compressor
10A sewage plant
20A workshop
150A inside panel

I'm talking about pulling the dryers and cooktop wires out of the wall into the attic. I can do this w/o disturbing the integrity of anything. Then running a heavy gauge wire in conduit up the side of the house, through the soffit, into the attic, into a small subpanel. This subpanel would feed the 3 disconnected devices. This way I don't have to buy a complete new run of wire for the dryer#2/etc. That wire is pricey. The subpanel solution would allow me to not have to tear into the wall, fix the wire(s), repair the wall, repair the shelves.

This solution would also allow me some future expansion capabilities. It's sounding better and better.

If you need to find the breaker the wire goes to:

Tracer

There are others on the market.

[ QUOTE ]
14C said:
If you need to find the breaker the wire goes to:

Tracer

There are others on the market.

[/ QUOTE ]

Breaker was easy to find..... it was flipped.

Make sure you have working smoke detectors in all necessary locations in your home. This is how most home fires start. Good luck.

Turbodog, I think I'm getting a little closer to understanding your setup there. Code does allow several main panels, 4 or 6 or something like that, so that is no problem.

They are expensive though, considering all they are is a metal box with a bunch of holes drilled through them in strategic places /ubbthreads/images/graemlins/wink.gif

If that lets you bypass all the potentially damaged wire, then that sure sounds like the way to go. But do check with the electric company about what you're able to do as far as the main feed. I know this is different for various local codes all over. Some places will let you run the main feeder from the meter, some places require that you have that done and then you can run all the branch wiring, some places just want to require that you get the other inspected.

In any case, call them first, most likely as the home owner you can run it yourself, but they will want to have it inspected, or inspect it themselves prior to re-connecting the meter. Better you call first and find out you can't get an appointment till next week, than spend the week without power turned on, or have to turn it on yourself against their wishes. They really hate that stuff and while they will turn you on eventually, they can be real jerks about making you wait and be as miserable as possible over stuff like that...

I guess I'm missing something. I've cut holes in drywall and patched it so that it looks very clean. I've also run wires and panels. I would chose the drywall every time. A small saw will cut a nice clean line in the drywall. I know that there are several "trim saws" that have little 4 inch round blades. Basically, a mini circular saw. Skill has one as does Mikita.

Chances are you've run the nail through the wire's insulation and chances are that all you need do is remove the nail and patch the insulation (assuming the wire is not badly nicked).

Adding a new sub panel will be more expensive and will take more time than cutting and patching an access hole even if that access hole is several feet long. It's also potentially more dangerous to add a new panel.

I have a stud sensor that also has a built in metal detector. It's made by Zircon. Less than $30. You should be able to use that to see where the wire run crosses your string of nails. That should make your access hole fairly small.

So for the price of a saw, a stud sensor, some drywall mud and some paint you will have a good fix. It will be safe and won't require climbing through the attic nor will it require a building permit and inspection.

And you get to keep the tools! /ubbthreads/images/graemlins/smile.gif

Daniel

[ QUOTE ]
gadget_lover said:
I guess I'm missing something. I've cut holes in drywall and patched it so that it looks very clean. I've also run wires and panels. I would chose the drywall every time. A small saw will cut a nice clean line in the drywall. I know that there are several "trim saws" that have little 4 inch round blades. Basically, a mini circular saw. Skill has one as does Mikita.

[/ QUOTE ]

If you do use a saw, please make sure all of the wires are not hot, especially if that are already damaged. The overall goal of the project should be to avoid any shocking experiences. /ubbthreads/images/graemlins/smile.gif

-Mike

[ QUOTE ]
gadget_lover said:
I guess I'm missing something. I've cut holes in drywall and patched it so that it looks very clean. I've also run wires and panels. I would chose the drywall every time. A small saw will cut a nice clean line in the drywall. I know that there are several "trim saws" that have little 4 inch round blades. Basically, a mini circular saw. Skill has one as does Mikita.

Chances are you've run the nail through the wire's insulation and chances are that all you need do is remove the nail and patch the insulation (assuming the wire is not badly nicked).

Adding a new sub panel will be more expensive and will take more time than cutting and patching an access hole even if that access hole is several feet long. It's also potentially more dangerous to add a new panel.

I have a stud sensor that also has a built in metal detector. It's made by Zircon. Less than $30. You should be able to use that to see where the wire run crosses your string of nails. That should make your access hole fairly small.

So for the price of a saw, a stud sensor, some drywall mud and some paint you will have a good fix. It will be safe and won't require climbing through the attic nor will it require a building permit and inspection.

And you get to keep the tools! /ubbthreads/images/graemlins/smile.gif

Daniel

[/ QUOTE ]

Stay tuned for pictures...

Anyway, one main problem is the wires are behind the end of a set of shelves that are made of some quite expensive wood. Secondly, the wall is an exterior one..... full of blown-in insulation, the kind that doesn't go back in very well on a second try. Furthermore, I can't find which wire got hit by the nail. My multimeter shows no voltage or continuity to any nail head to any wire. Lastly, I already HAVE all those tools! Maybe I need a good flashlight instead?

/ubbthreads/images/graemlins/tongue.gif