This is not really RV related but some electrical expert will hopefully answer.I inherited some wiring that is run from my garage through underground conduit to the back hard, about 100 feet away. I'm installing a receptacle in the back yard. Problem is I need to identify the wires in the j-box in the garage with the receptacle in the back yard; it's not a simple matter of having a black, a white, and a ground; there are several wires in the conduit; 3 blacks, a red, 2 whites, and something else. I just need a simple 3-wire install for a 120 receptacle but need to match up the wires at each end if that makes sense. Any ideas?

Yes.Get a 12 volt battery. Jumper test leads, and a 12 volt test light.Turn MASTER WHOLE HOUSE CIRCUIT BREAKER OFF. Then every individual breaker.Verify verify verify the breaker panel is dead.Connect battery leads to load end out on the patio. White is neutral common so make that your negative battery connection.Connect 12 V + to black wire in questionTake test light to breaker panel.Stab the breaker outlet screws.Which breaker lights up?Ain't cool to have multiple wires connected to a single breaker, but if that's the case, remove wires to isolate then re-test.At the load end, feeding a receptacle can make things tough. False negative readings. A GFIC receptacle makes it impossible. Take the receptacle out of it's duplex and connect wires directly to screw terminals. Hint. Unplug things if you get strange readings during the test. If you have to, unplug everything in the house when testing.

I work in the telecom industry and we use a Toner device that has a tone generator that attaches to a pair of wires on one end, then a Wand is used to find the tone on the wire on down the line in a bundle. Works very well for wire ID. I would think you could find one at a Graybar (or other type tech warehouse store) in your area. Or online.

There are wire tracer/signal injector tools available for this sort of task. Here is a Harbor Freight example.These are conceptually not that different from Mex's suggestions, but can be a little easier to understand and use in practice and have the advantage of working via an inductive pickup so there's no need to pierce or strip the wire insulation. That's probably not a big advantage in your particular situation.You can also deduce which wire is which by selectively shorting wires and measuring the continuity at the other end. It can take at least a few trips back and forth and some care in labeling and note-taking to be accurate.

Since you say you have one red or any other one color for that matter. The cheapest way is to make sure all wires are disconnected at both ends. Next on one end jumper red to any wire then go to the other end with an ohm meter and take a measurement from the red to each wire until you find the one shorted. Mark it with tape and then move on to the next wire shorting it on one end. Easy Peasy.

How to identify wires? | Good Sam Community

13 Replies

Ron3rd
Explorer III
Jun 29, 2017
pickjare wrote:
Read carefully what bdpreece posted. That procedure is exactly how I would do it.

I agree
pickjare
Explorer
Jun 29, 2017
Read carefully what bdpreece posted. That procedure is exactly how I would do it.
joshuajim
Explorer II
Jun 29, 2017
MEXICOWANDERER wrote:
Ain't cool to have multiple wires connected to a single breaker...

Not true. There are some breakers that are certified to connect 2 wires, but they must be labeled as such on the breaker. i.e. Square D's QO series
mobeewan
Explorer
Jun 28, 2017
You'll shoot your eye out.:R
drsteve
Explorer
Jun 28, 2017
Johno02 wrote:
Call an electrician before you burn something up.

O ye of little faith...
Johno02
Explorer
Jun 28, 2017
Call an electrician before you burn something up.
bdpreece
Explorer II
Jun 27, 2017
Redneck Technology.
Ron3rd
Explorer III
Jun 27, 2017
bdpreece wrote:
Since you say you have one red or any other one color for that matter. The cheapest way is to make sure all wires are disconnected at both ends. Next on one end jumper red to any wire then go to the other end with an ohm meter and take a measurement from the red to each wire until you find the one shorted. Mark it with tape and then move on to the next wire shorting it on one end. Easy Peasy.

Very good advice. Thank you.
bdpreece
Explorer II
Jun 27, 2017
Since you say you have one red or any other one color for that matter. The cheapest way is to make sure all wires are disconnected at both ends. Next on one end jumper red to any wire then go to the other end with an ohm meter and take a measurement from the red to each wire until you find the one shorted. Mark it with tape and then move on to the next wire shorting it on one end. Easy Peasy.
Ron3rd
Explorer III
Jun 27, 2017
Good info folks

Thanks