Tips for ID'ing a short in outlet? (plus other novice questions)

[Sam_Bklyn]

Hi,

I'm trying to move a single duplex outlet about 6" down a wall in my apartment's kitchen (and make it a double duplex in the process). Everything is wired, but my voltage detector goes off about 3 inches away from the newly installed box itself, indicating that it might be hot (?). Some details...

What was there before: a single old work box with power coming from the ceiling via 12/2 armored cable. This is on a 15 amp circuit.

What I did: installed new 2-gang old work metal box on stud in the new spot; pigtailed wires in existing box with 14-gauge wire, covered box, and ran wires down wall; pigtailed two wire segments to the black wire and two to the white wire coming into the new box and screwed ground to back of box and pigtailed 2 green wires to that; wired both outlets (blk to brass; white to silver; green to green). Everything has wirenuts and electrical tape. (I did test the black wire coming INTO the original box to make sure it wasn't wired backwards.)

My main question: what should be my process for identifying what's causing the short? Is there a troubleshooting method?

Also, how do I tell if there's REALLY a short? A while ago there must have been some stray current in our steel desk--though you couldn't tell by touching it. If my wife touched the desk with her hand, I could touch the detector to her head and the thing would go off. A great party trick, but I wonder if the detector might just be really sensitive. For this, maybe it's just picking up the bundle of black wires folded in the back of the box (?).

Some other questions that might have been helpful 48 hours ago:

-A hardware store employee steered me away from romex or armored cable to run the 6" between the boxes, insisting it's fine to run 14 gauge black/white wires inside some flexible plastic tubing--the flimsy kind usually used to bundle/organize wires. In retrospect this seems unwise (and potentially illegal). Any thoughts?
-The 2-gang box I bought has a nailer plate to go onto a stud (again at the advice of the hardware store guy), but our plaster walls have an inch or more of material before you get to open space. With the box nailed to the stud, it's pretty far back from where the outlets need to sit. Should I have just gotten a regular box (with no nailer) and plastered it in closer to the wall surface (maybe with a screw going through the inside of the box into the edge of the wall material)?
-Whoever installed some of the outlets in our house wrapped electrical tape around the backs of the outlets to cover up the screws/contacts. Is this standard/recommended practice?

Sorry for the long post (my first here!) and, of course, for any and all advice.

Sam

[HayZee518]

first of all the hardware guy is way off base. putting wires in a plastic sheath is a no-no. you use type AC cable 14/2 with ground. the existing box uses a metal clamp to hold the armored cable in it. what you need to do is pry out a bottom knockout, install a similar clamp with screw. leave about 6 inches of slack cable in each box. insert the metal jacket into the knockout and screw down the clamp. do the same in your new metal box but use a top knockout. metal boxes are gangable, if yours has a stud bracket use it. in your original box - black to black, white to white. the ground is automatic with the armor. outlets hot to brass and the other brass, white to nickel and the other nickel. if you have a green wire it should bond to the box and the green screw of both outlets. for your voltage tester - get rid of it. it is an induction tester and will always false read a hot circuit. get a square D "wiggy" or a similar tester made by Ideal Co.

[Sam_Bklyn]

Thanks HayZee518. That's really helpful. Should've gone with my gut on the armored cable, I guess.

I think my super has a tester like that, but it might be worth investing in one if they're not too expensive.

I'm still of mixed mind about attaching the box to the stud. The nailer plate attaches to the 2" edge of the stud and so has to be placed pretty deep in the wall. The big gap that it would create between the box and the screw plate on the receptacle bugs me, though I suppose it would be encased in the wall cutout.

There are other boxes that attach to the side of the stud, but then I'd have to knock out a bigger portion of wall--above and below--and then figure out a way to create a level patch (since screwing a piece of drywall to the studs would only be about half as thick as the existing wall material). I'll figure that out, I guess. I'd like to have a securely attached box, but it might not be worth it.

I'm starting to really appreciate modern drywall.

Anyway, thanks again for the advice.

Sam

[HayZee518]

the other alternative is to use a ganged metal box with "madison clamps" these are stamped pieces of sheet metal that hold the box in the wall against the "box ears." the other way is a two gang plastic box with screw ears that rotate against the back of the sheetrock when you tighten the screws.

[Speedy Petey]

A real tester should be mandatory for anyone doing any electrical work.

Also, do yourself a favor and replace that cable with #12 AC or MC cable. There should have been NO reason to mix wire sizes in a case like this.

[Sam_Bklyn]

Thanks HayZee and SP. This seems doable. The hardware store near me only sells the 12/2 by the foot (the 14/2 only comes in 25' rolls), so that works better anyway. And I suppose there's no harm in using heavier gauge on the 15 amp circuit.

HayZee I'll check on those Madison clamps. I did a Google search and the first thing that came up was another post from you on this forum.

Thanks again guys.

Sam

[Speedy Petey]

The hardware store near me only sells the 12/2 by the foot (the 14/2 only comes in 25' rolls), so that works better anyway. And I suppose there's no harm in using heavier gauge on the 15 amp circuit.

It's not that you are using heavier wire. It's that you are not mixing wire sizes. Someone may come along and see #12 and switch the breaker to a 20A, which it should be anyway in a kitchen. This is only safe if ALL the wire on the circuit is #12.

[Sam_Bklyn]

It's not that you are using heavier wire. It's that you are not mixing wire sizes.

That certainly seems prudent, SP. My point was just that while I understand it to be dangerous/illegal to use a lighter gauge than recommended (like #14 on a 20 amp circuit) using heavier gauge (like #12 on a 15 amp circuit) doesn't carry that risk. But it's worth remembering that mixing wire sizes can lead to future mistakes, as you point out.

I doubt I'll switch the breaker to 20 amp, given that I don't know for sure what size wire is on the rest of the circuit. Thankfully, the appliances on the opposite wall of the kitchen are on a separate 20 amp circuit. I'm guessing that happened when the kitchen was renovated (in the 90s I think).

Thanks again. Sam