I have a minor electrical issue that I'd like to see if anyone has any trouble shooting suggestions.

Problem: exterior light outside of the garage door, switched just inside of the garage door stopped working.

Steps taken so far:

I used a current sniffer and found there is power to the switch. The switch does cut the current off and on and the power does go through the wire to where it exits the switch box. It is not hot at the light junction. Somewhere in the 3-4 feet the romex travels it is compromised is all I can determine but I don't know why, when or how that would have happened. There are a few screws in the drywall but nothing added in between the time it was working and now.

Do I gotta cut drywall?

Is it a 3-way switch?

Great question. I am 99% sure it's not but just for the 1% chance here are some pictures. If so I don't know where the other switch is or why that would make sense with the setup.

Nope, not a 3-way.

Disconnect the switch and fixture and ohm out the wires between them (don't forget to turn off the breaker first). That will tell you for sure if you need to bust open sheetrock or if you have some other weird problem to chase down.

If it's the wire and the run is short enough you might be able to just fish a new one and leave the walls intact.

Thanks!

Johhny,

What happened?

Failure of the wire inside the wall with no recent work would be unusual.

I'm going to take a wild guess and it's the switch and, no offense, user error on the voltage detector.

None taken. This is why I asked here, seemed too weird. The only thing I could think of is the romex may have been damaged/punctured by a Sheetrock screw way back and finally shorted out? I was able to get the current out to toggle with the switch by the indicator so that increased my confidence that I was getting a clean signal but not to 100%.

I'll try turning off the breaker and bypassing the switch to see if you are right. Thanks!

Also, I don't have a voltage meter to test the ohm. Anybody have a recommendation for the type I would need? I am not anticipating lots of use.

Turns out my hunch was right. I removed the box at the exterior to see how difficult it would be to fish another wire and noticed a screw in in the blocking directly over the romex. I removed it and the end was melted. I also was able to poke the voltage sniffer far enough toward the place where the puncture was to get a reading so that's for sure where it was.

Now I am left with solving the wiring issue. Luckily it is an unfinished wall, and also a supremely short and straight shot from switch to junction. Based on the pics below I am inclined to cut the Sheetrock and run the few feet of new wire, or maybe if I am stupid lucky there will be 6-8 inches of slack to get past the puncture spot.

Any easier method I am missing here? I don't see fishing a new wire being that easy but I have never done that before. The x on the wall indicates the location of the exterior light.

You could put a junction box on the inside and splice on some new wire, but patching drywall isn't that big a deal and you can do a combo of fishing a new piece of romex and cutting some drywall where necessary. It looks like you might be in the same stud bay so it could be pretty easy. There may be a fire block running horizontally in that bay and if so you probably have to cut the drywall just below it. If you cut out some of the plywood in that circle hole on the outside you might not need to make a drywall hole where the X is. You'll have to cut a whole above the switchbox so you can get the romex in the connector properly.

Are the wires in conduit? Any opportunity to use the existing wire as a pull string, and pull in new wire?

That would make it easy, but romex would almost never be in conduit and the conduit should stick out the hole to the outside wall if it were. It's pretty unlikely that the romex could be used to pull new romex as it's probably stapled, but it could be free. If there's no horizontal 2x4 fireblock though and it's in the same bay you could possibly get a larger gauge solid copper wire (like #10 or #8 - or something like that - wire like a coat hanger) fed through and use that to pull the new wire.

You can get a 25' fish tape for like $10.

Fish tape might work, but is too floppy. #10 bare copper wire is perfect for that, or #8 if there's insulation you have to poke through. Fishing something through a finished wall is something I've done a few hundred times getting a new circuit into a service panel from the outside through the stucco.

what about taping/twisting the new wire to the existing bad romex and pulling it through?

Like I mentioned in an earlier post, that's worth a shot. The romex is probably stapled, but it just takes a tug to tell if it's going to move.

dat's wat she said.

So I completed the repair. After giving it a tug (that's what she said) it was clear there was at least one staple. I cut a small hole between the studs by the x and was pretty surprised to see how bad the shorted wire was burned up. It kind of scares me because the breaker did not flip and there was power going to the short for an undetermined but extended period of time. When I pulled on the wire from up top to see if I could get enough slack to feed it through the box to the exterior it broke very easily from burning through. Because of this I just decided to run a new piece of romex--it was only about a 3' run.

Of course there was a block. Of course there was a second staple under the block. Of course I cut a second hole below the block after dicking around with it tryna fish it through. The holes were easy to replace though and a lil mud and tape and it will be done for good.

That said, I don't know exactly how to feel about the wire issue. It seems that the breaker failed? Any insight on this? Here is another pic of the burned wire.


ETA this is the wire after I pulled it and broke it, but after posting the pic I noticed the black on the stud. I feel pretty lucky the house didn't go up.

What kind of breaker is it? Is it old? It can't really be that old as your house isn't that old.

It probably didn't fail, but you can replace it anyway if it makes you feel better.


And an arc is usually just going to be a one time thing that happens very fast and it burns up the connection and then stops. The insulation will burn away right near it and anything close will be scarred, but it shouldn't last long enough to come close to catching lumber on fire. I mean, electrical problems are common causes of house fires, so it's not like there's nothing to worry about, but electrical problems don't commonly cause house fires.

Are you in SoCal? I can't make out the city on your trash can, but your house and the neighbors have a very SoCal, just outside of LA feel, like Santa Clarita/Antelope Valley/San Bernardino/Riverside etc.

NorCal. House was built in 03 and I'm pretty sure as part of the home inspection they trip all the breakers. Still gives me the creeps and I am ordering the fire escape ladders for the second floor I have had in my cart on Amazon.

Anyway, that the house didn't burn down, I successfully fixed it, and add the fact I was right about what the issue was makes this a shining success in the books for my weekend warrior butt. I plan to bore the **** out of everyone I know for the next few weeks.

Thanks for the help y'all!

Tripping all the breakers is a lot of work for a home inspection and I'm not sure everyone would consider it advisable. If they just put a meter on each breaker they are making sure the breakers allow electricity to flow, not that the overcurrent protection works.

But 2003 is plenty new for breakers.

The breaker didn't trip? Because there can be a pretty good spark on a short when the breaker trips. Otherwise maybe it was an arc across a broken hot and the current was still limited. Or the resistance to ground was high enough through the screw/paint/junction box/whatever that there wasn't enough current to trip the breaker.

I can't say the fire escape ladder is a bad idea. You can't be too safe I guess. Testing the fire and carbon monoxide detectors comes before that.

If you want to be paranoid you can replace all your breakers with arc fault circuit interrupters. They're quickly becoming mandatory in new construction anyway because of what just happened to you.

Paranoid and rich.

No doubt, someone told me they were north of $200 each and were now required in bedrooms and bathrooms in new construction.


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