tlmgcamp
Well-known member
- Joined
- Jul 16, 2016
- Posts
- 834
Replacing bathroom fan/light/night light. Shut off breaker marked for the fan/light/night light. In junction box that housed the fan/light/night light switch I found a 3-wire (black, red, white, ground) coming in. The red wire when to the old fan/light/night light switch and the black went through the box to power the circuit for the GFI outlet in the bathroom. after removing the switch and pulling the wires out so I could see what I was working with, I checked the wires with a "Non-Contact Voltage Detector". This is not a meter. It is a gadget that detects voltage without needing to strip wire. It told me that both the red and black were still hot. After some investigation, I found that as long as either the red wire breaker OR the the black wire breaker was on, the voltage detector would show voltage in BOTH black and red, whether tested at the junction box or the panel. I am very sure that I know the route of the 3-wire and can see it for the majority of the length from the breaker panel to the junction box. It was installed 20 years ago during a bathroom renovation that i contracted out to do. The only thing that I could think of is that somebody accidentally put a nail or screw through the 3-wire and hit both the red and the black, making them act in unison. Of course, the chances of that happening without also hitting the white (common) or the bare ground seemed pretty slim. I went ahead and tested for continuity between the red and the black (breakers off) and found none, which seemed to squash the errant screw theory.
While pondering it over a beer last night, I decided to actually put a regular tester on the wires. At the panel with the red breaker off and the black breaker on, I found 110V in the black breaker wire, and 2V in the breaker red wire. Same result with red on (110V) and black off (2V). Can anybody suggest what might be going on here? Note the red and black wires at the junction box were not connected to anything during all these tests. Only the white (common) wires and bare ground wires for everything in the junction box were still connected.
While pondering it over a beer last night, I decided to actually put a regular tester on the wires. At the panel with the red breaker off and the black breaker on, I found 110V in the black breaker wire, and 2V in the breaker red wire. Same result with red on (110V) and black off (2V). Can anybody suggest what might be going on here? Note the red and black wires at the junction box were not connected to anything during all these tests. Only the white (common) wires and bare ground wires for everything in the junction box were still connected.