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I recently moved in to a 20 year old house, and have started to unravel some of the unfortunate short cuts the previous owner left, with regards to the electrical work. One trouble in particular I'm having is tracing my hots: there's cases where he had them tied into white wires, and split out onto three way circuits where I believe the hot and travelers area actually tied together somewhere. Constantly de-energizing the circuit and pulling out all the boxes and disconnecting the receptacles is super tedious, and even when I do make progress, where I find hot wires coming back at the switch boxes makes no sense.

I've seen the tone generators and breaker/circuit tracers, but is there a good tool to use that will allow me to map an individual conductor to approximate the path of the hot I'm seeing currently without the risk of using 120v and a non-contact tester all over the place? Basically, can I clip something on to my hot (de-energized) line and get kinda close with the tone generator function, and then find exactly which conductor(s) are then connected to it? Thank you for any thoughts!

Two additional notes: 1. this house is a prefab - built in two parts and shipped in, then placed on a poured foundation. It was partially pre-wired, and the two halves of the house were connected later. While likely to 90s code, some of the methods seem unconventional (I'm not saying wrong), but the bigger concern is that originally Rv-style self-contained outlets and switches were used, and they're past their lifetime. Most have been straight swaps. The previous owner though took some additional liberties and took what might have been mildly confusion and made it concerning, potentially dangerous. (see note below).

  1. My end goal is to also write in a number of home automation switches that requires neutrals, so ensuring that this are accurately identified, traced and labeled is important, hence my question.

Edit - @Harper - while I'm no Master Electrician, and still learning more of the advanced circuit possibilities, I'm judging based on a number of observations. For instance, the three way switches for the ceiling fan wouldn't work correctly (would switch one leg, but the other switch would shut off the whole circuit), and after pulling out the switch box from the wall, I found two previously unknown switches electrical taped "on", stuffed down into the wall cavity. Tracking then where the wires connected to those switches went has led to more fun findings, like wires just twisted and taped loose in multiple boxes. So yes, I definitely have more to learn, but I believe these are items that definitely qualify at a minimum as mistakes.

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    How familiar are you with electrical? Reason I ask is it is quite common for people new to electrical to see a lot of mistakes in the previous persons work... that are actually not mistakes but merely something beyond their experience. Multiwire Branch circuits were a real eye-opener for me. – Harper Jun 16 at 15:46
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    Get your self a good multi meter . With continuity in it. And if you see a double breaker feeding a 12 or 14 wire may be a multi branch circuit and wires have to be splice together then go to outlet. if you loose neutral all types of trouble, Can get 240 volts out of 120 outlet blow up tv refridge ect. Read up on this before you go on . – user101687 Jun 16 at 16:07
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    When you find white wires and the are hot and circuit checks out re,id them with black tape or marker. it is code a some guys do not do this simple step. – user101687 Jun 16 at 16:19
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    What do you mean by "hot wires coming back at the switch boxes"? If the house is 20 years old then you will have wall switches without a neutral. The cable from the switch to the fixture or to a switched receptacle can be two insulated conductors (B & W) plus bare copper ground. In this case the W can either be an always hot or a switch hot. This was standard for that time. – Jim Stewart Jun 16 at 18:23
  • @Jim Stewart - to clarify, an entirely new breaker panel was installed prior to our purchase. The white wires for each 14/2 are connected to a neutral bus bar in the panel. Each wall switch measures 120v between line feed hot and white, so I believe this to be truly wired as white neutral. – adryan16 Jun 16 at 22:06
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A method I have used in the past is to have all the breakers disconnected for safety (old houses are known to have "crossed circuits"...

Then have a very long cable back to the distribution board connected to a particular wire to test, then use the multimeter to test the object wires at the point of interest. Label as necessary (even down to tape with text...).

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Sounds like you really do want to identify/map every cable segment, and possibly every conductor in every cable in the house. A tool used for this in the telecom sector is a tone generator and amplifier probe. Extech 40180, Fluke PRO3000, and Progressive Electronics 200EP/77HP are examples. I've used the Fluke and own a Progressive (got mine used on eBay). The tone generator box fits in the palm of a hand, runs on a 9V battery, and connects to the cable under test with a pair of alligator clips. The inductive probe picks up the signal on the cable, getting stronger (louder) as the probe gets nearer to and finally touches the conductor.

You'll have to de-energize the circuit and disconnect loads. The tone will travel everywhere the conductor goes. Disconnect switches, outlets etc to break the circuit into smaller segments as needed.

Sometimes I connect just one lead from the generator to the conductor of interest, for example when working on a circuit where the second conductor in the pair goes everywhere -- the negative in automotive, for example. Results are kinda so-so; it works best when the two generator leads are connected to conductors in the same cable.

  • Honestly, yes. Which as I read your comment signs a little crazy, but I'd rather just know and mark it now, as we'll continue to add and pull new circuits, and knowing what's already there will help. Thanks for confirming! – adryan16 Jun 18 at 2:25

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