I am diagnosing my well line electrics. I have a non-contact voltage detector. At about 10" from the box, it shows live, and after that dead. Oddly, on the other side of the wire, the live signal extends perhaps another 8" past that, then dies. Visual inspection reveals an intact sheathing. Everything upstream checks out with the tester. When the breaker is shut off, everything goes dead, so it appears not to be secondary wire interference.
How common is a wire break in (I believe) 12/2 cable. It's 220V for a submersible well pump. Any help is appreciated. Shall I cut the wire at the break and install a junction? Is there an easier test without cutting the cable?

  • Is there a junction box where the cable enters the wellhead, or is it a single continuous run? – ThreePhaseEel Aug 18 '19 at 13:52

As guy that did this trade all his working life, I can DEFINITELY tell you that these proximity / non contact voltage detectors ARE NOT to be depended upon 100%.

They have their place and time, and they are to be treated as such. I have a Fluke™ Volt Alert 1AC-A II and while it's a great tester, it definitely is not the "End-All" of testers and it cannot ever be replaced by a wired / probe / lead tester.

I use these proximity testers for "quick and dirty" GENERAL testing purposes.

Get yourself a Fluke™ T5-1000 from Home Depot or Lowe's

  • I use both of those and they are quality tools although I don’t like the round probes on the t5-1000 the less expensive t5-600 are flattened and fit into 15a receptacles, the round probes was the only thing I did not like but a belt sander fixed the shape issue, these things both of them last I had 1 take a 2?hour swim , took it apart dried out , new batteries and it worked fine (the meter that is). + – Ed Beal Aug 19 '19 at 15:49
  • Yeah for industrial and non in depth testing, the Fluke™T5-1000 is a great tool to always have with you. And a nice proximity tester is good to have for the "quick and dirty" times one needs it.🙂 – Retired Electrician Aug 20 '19 at 21:21

You should get a good voltage tester and check the wires at the junction box or where it connects to the well. 12/2 doesn't usually "break" and if it was way overloaded it would have burned in half or at least melted the insulation. If you determine there is in fact a break you can install a junction box.

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