I have (1) 12/3 wire coming in to the box for the dimmer switch, lights started blinking, 3 lights on this circuit and then they finally went out. When I checked the wires red, black and white, white to ground read 120 volts, red and black to ground read nothing, white is the only one that's hot what would cause this could squirrels in the ceiling bit through the black or red and caused white wire to read hot now? Ty for any information

  • 3
    Is it a simple single pole dimmer switch or a three way switch(two switches control the lights? Is the white wire connected to switch?
    – crip659
    Mar 8 at 23:37
  • 2
    Odds are good that if you flip the other switch the wire that's hot will change. Since it seems likely that it's a 3-way switch and the white is one of the travelers. But sure, could be squirrels.
    – Ecnerwal
    Mar 9 at 1:26
  • Can you post photos of the insides of the boxes involved please? Mar 9 at 4:42
  • There is only one switch and how do I post a photo from my phone,ty. Mar 9 at 13:57

1 Answer 1


You have a switch loop

"One cable into the box" is the dead giveaway.

And an old-style one, from the sound of it. This is using white for always-hot, as Code requires. The other two are switched-hot, to allow separate control of two things, e.g. two banks of lights, or light+fan.

It's possible the last installation fed both switched-hot wires from the same dimmer, or the fan is missing. In such a case, it may be possible to rewire the switch loop to use white as actual neutral, black as always-hot and red as switched-hot, in the post-2011 wiring style.

  • 2
    And, any attempt at a rewiring should be proceeded by a new question here including pics of the wiring in this box as well as the wiring at each of the light fixtures involved. (At a minimum, it will ensure the OP has "before" pics for when things go pear shaped afterwards.)
    – FreeMan
    Mar 9 at 13:22

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