There is one cable with exposed wires. A voltage tester does not detect anything. Another cable goes into a junction box for the doorbell transformer. The cable in the junction box also has no power.

How can I troubleshoot the two cables with no power? All the breakers in the circuit box are on. Do I need a remote continuity tester? Is that safe to use at the circuit box?

Edit: this is the cable running into the junction box. The other cable with exposed wire is not pictured. junction box

  • Can you provide a picture of the offending wire? – Aloysius Defenestrate Sep 22 '18 at 22:05
  • And are we talking about a wire (1 wire) or a cable (several wires inside a plastic jacket)? Any writing or lettering on the thing? For scale, shoot it laying across your hand, this will also make the autofocus work better. Autofocus can't target wires. – Harper - Reinstate Monica Sep 22 '18 at 22:10
  • It's a cable with 3 wires inside (see picture). White, brown, and green. – Reed G. Law Sep 22 '18 at 22:16
  • Have you tried to follow the cable along the ceiling joist to see where it goes? Possibly it enters a top plate and goes down into a wall where it could be traced to another electrical box. – Michael Karas Sep 23 '18 at 15:22
  • @MichaelKaras it goes down a wall with several other cables. I was looking for suggestions on how to trace it at that point. There's only one circuit breaker box. – Reed G. Law Sep 23 '18 at 21:03

I ended up buying a wire tracer and found the cable led to a bathroom switch. After opening the box I found the cable unconnected. I connected it up and now the doorbell works!


This is a doorbell transformer low voltage 12 or 24v in most cases most non contact testers need ~ 32v to 75v to detect a hot, so your non-contact tester won't think it is a hot but a volt meter will show a voltage.

Is your doorbell working? I would say in 99% of the time this is the reason it works, very common and a non-contact voltage tester can't see it. The primary wiring on the other side is detectable - the cable feeding the box will show hot.

  • The multi-meter doesn't detect any voltage on the old transformer or the new one I replaced it with. With the transformer off a voltage tester doesn't detect anything from the house wires. – Reed G. Law Sep 23 '18 at 2:25

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