Voltage on circuit with breaker off

[mtiede]

Ooops, I just noticed this forum was "For Electrical Professionals". I have a Physics degree. Does that help? ;-)

So I was trying to replace a fan switch in a bathroom to a countdown timer switch. I bought 3 of these and already installed the other 2. Now I'm about to do the last one and I'm confused. I turned off the breaker and the fan and light are now in operable. But my contactless voltage tester is showing something is hot there. I measured from each of the switch screws to ground with a voltage multimeter. It showed no voltage (maybe .005). Should I be worried about what is in the box?

All 4 of the black wires coming into the box are held together with a wirenut. And also for the whites. And grounds.

Is there something I'm not understanding here? Is the contactless meter just picking up a ghost voltage from a line run in parallel with the line turned off? I'm afraid to touch anything because I don't know what is happening on the tester in this situation that was not present in either of the other 2 installations. (or any other time I've used the contactless tester)

Thanks for any information.

(I also worked with LED circuits in my college class in 1966. And I built a nuclear magnetic resonance spectrometer while in High School in 1964 or so. Not fancy like the ones now, very basic)

 

[mtiede]

(I see from the email I received, that this post/thread may be deleted without notice since I am not a professional electrician. Sorry for the intrusion if that is the case)

 

[GoldDigger]

Ooops, I just noticed this forum was "For Electrical Professionals". I have a Physics degree. Does that help? ;-)

So I was trying to replace a fan switch in a bathroom to a countdown timer switch. I bought 3 of these and already installed the other 2. Now I'm about to do the last one and I'm confused. I turned off the breaker and the fan and light are now in operable. But my contactless voltage tester is showing something is hot there. I measured from each of the switch screws to ground with a voltage multimeter. It showed no voltage (maybe .005). Should I be worried about what is in the box?

All 4 of the black wires coming into the box are held together with a wirenut. And also for the whites. And grounds.

Is there something I'm not understanding here? Is the contactless meter just picking up a ghost voltage from a line run in parallel with the line turned off? I'm afraid to touch anything because I don't know what is happening on the tester in this situation that was not present in either of the other 2 installations. (or any other time I've used the contactless tester)

Thanks for any information.

(I also worked with LED circuits in my college class in 1966. And I built a nuclear magnetic resonance spectrometer while in High School in 1964 or so. Not fancy like the ones now, very basic)

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