Detect current through romex?

[edro]

I have an ancient house with wiring going everywhere.
I am tracing out the breaker panel, and have identified most of the outlets and light sockets using a Harbor Freight circuit detective and by trial and error by flipping breakers.

I would like to clean up the wiring some (offload some of the heavily loaded breakers), so I need to be able to identify where certain wires are going.

I want to be able to detect current going through Romex. Then I could pull current through an outlet (using a heater or something) to see if the Romex I found in the basement is feeding that outlet.

A standard current clamp won't work because both conductors are in there. Also, I don't really want to cut away the insulation to pick out just one conductor, as that would be difficult. I also don't want to just cut the Romex, as that is destructive.

I just want to be able to detect current through the insulation.
Those proximity voltage detectors just detect voltage, and would not help me.

Anyone have any ideas?

 

[skyking]

test it at the breaker box, and at any junctions where you can pull out the black without stripping it.

 

[edro]

That's a good idea to look for junction boxes.
Most of the romex in the basement goes directly into a wall area, then comes back out and is routed through the basement to each room.
On top of this difficulty, most of the romex is old and painted, so it's difficult to even compare insulation style/color/age.

 

[skyking]

you are overthinking it a little.
1) turn off anything that will be affected by a power surge, computers and the like.
2)switch off a breaker and go map it out. determine what lights don't work, outlets, etc.
3)repeat process till you know what goes where.
4)make a diagram, use colors to represent different circuits.
5) go back and heat up a single circuit at a time, use your detector and positively identify wiring away from boxes.

That should do it.
Now you can decide where to run a new circuit. I personally tend to run fresh wiring on new breakers to outlets first.

 

[edro]

I have already mapped out what breakers control what and have a general idea of where the wiring goes through the house.

In one example, I have a romex that appears to be going into a room that I want to offload onto another breaker. That same breaker feeds various outlets in 4 different rooms. I need to verify that this particular romex actually feeds the room I wish to offload, so I can cut it in the basement and route it to a new breaker.

Great... now I'm the #1 Google result.

 

[skyking]

turn it off, back on, use your "sniffer" to confirm.
What do you plan to do, put a junction there and make a new run from the junction back to a new breaker?
If you do, be sure to use the appropriate wire size and breaker. If the wire you cut into is a 14GA, stick with a 15 amp breaker.
That right there is why I try and home run some new circuits all the way with 12 GA.

 

[edro]

What do you plan to do, put a junction there and make a new run from the junction back to a new breaker?
If you do, be sure to use the appropriate wire size and breaker. If the wire you cut into is a 14GA, stick with a 15 amp breaker.
That right there is why I try and home run some new circuits all the way with 12 GA.

Yeah, that's my plan.
Luckily, most old wiring is 12GA.
I haven't found a 14GA wire in the house yet.

 

[SpatiallyAware]

I have a tool that beeps and blinks if it gets near AC current... Perfect for something like this.. IIRC it was $40 or so at home depot

Edit: NM reread and realized this won't work for what you're doing

 

[feralkid]

Yeah, that's my plan.
Luckily, most old wiring is 12GA.
I haven't found a 14GA wire in the house yet.

Are you sure? You referred to the house as "ancient".

If it hasn't been rewired since built, it's a safe bet there's a lot of 14 guage wire.

 

[drnickriviera]

I believe what you are looking for is a non contact voltage detector. Greenlee makes one, home depot may even stock it.

Ahh, NM, you said current. There is a thingy that you plug into an outlet and it has a handheld device that you use in the breaker box to tell which breaker goes to that outlet. I don't see why it wouldn't work on romex