ECN Forum Forums General Topics of the Trade General Discussion Area Toner and Probe Wire Tracing Tips

I would try clipping to the metal jacket to trace MC behind a drywall.

is the greenlee line voltage or cat5/6 type, as the ideal one? I've heard seen a Tic Tracer but cannot remember if it found wire/cable on live or dead circuits, my understanding of the TDR unit, by JTE is that it gives you total short length, so if it reads 25 feet then the short is 12.5 feet away, what I believe I'm looking for is a melted section of wire, in a box or in a wall but cant seem to get toner to ring out of cable? The red conductor still works the lights, i always get a load type continuity ring on my greenlee volcon, and the black non-working conductor rings constant continuity indicating a short....didnt have a regular volt/ohm meter on test day...and this flu isnt helping either, what sort of reading should I be getting on the downstream conductors with the black red white disconnected from panel, but green and jacket still bonded?

MC tape/sheach/metallic wrap should be bonded to the system ground endlessly.

Toners can't pump grounded conductors -- they function as micro-radio emiters -- and the pumped conductor functions as a feeble antenna.

The receiver has a variable pick-up circuit so as to just barely pick up the primary emitter.

This is how it's possible to walk down the conductor.

This also explains why 9VDC batteries don't last hardly any time at all: they're being drained at full flow.

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Even though the sheath suppresses the signal, one can pick up the hot spots every time the conductor enters an (unshielded) junction box. This is often more than enough to dope out the situation.

All tested conductors have to be un-loaded, broken out of circuits.

ONLY the hot should be pumped, the neutral is VERY problematic in old work.

The Greenlee gadget will immediately indicate when its being drained into a short. It can't deal with 'bolted shorts.'

You can spot which leg has been ruined by isolating it from both ends.

It's extremely common for j-men to assume that the cable has been damaged -- when that's the last possibility.

It's far more likely that someone's mis-wired the cable, or that it's tied into a load that is internally faulted... even a flaky receptacle is enough to cross hots to neutrals -- and get to ground.

In old work, conductors are far more likely to fail in and around junction boxes -- it's the heat of utilisation and it's where bad make-up compounds into failure.

In my specific experience, I've only had one experience of drywall screw penetration. Even it only tagged the hot. That was enough to ground it: tin framing.

(When routing MC, stay away from drywall screw pattern zones.)

On this same subject, fire alarm, data, intrusion wiring etc.is more often faulted because of the common practice of attaching to threaded rod, running in open ceilings and being damaged during installation. For years I spent much time going back after installation was supposedly complete and locating grounded cables in high rise buildings. (You cannot pull more conductors through a 4" pipe with a 1/2" rope after the initial install is done).
I found that TDR tracers were very helpful for distance. Also, using an analog meter like the Simpson 260 was also helpful to locate grounded wiring and estimate distance. By opening up the circuit and checking resistance to ground with the 260 I could figure out whic direction the fault lay in. Parking lot lighting could be similarly trouble shot using a megger set on 250 volt dc. Digital multimeters are harder to use for ground faults because they are sensitive to transient voltages.

does the meteal jacket have to be isolated from bonded panel to carry tone, seems the only tone I get from the unclipped (loose) lead. i dont have a test space or lab to test equipment.....