North American home from ~1960s. Unfortunately I dont have a "before" picture of the old fan wiring. Trying to install a new fan which has a light, controlled by a dimmer switch on the wall. Things get weird when I connect it (i.e. hallway lights don't work, one receptical in this bedroom seems to show as two hot wires instead of a hot and neutral, ceiling light in another bedroom doesn't work). So somewhere some wiring is messed up. The wires coming down from the light fixture hole in the ceiling are:

  1. One white wire (say 14 gauge). Cheap non-contact voltage detector seemed to detect voltage.
  2. Two thicker black wires, in a twist connector. No voltage detected.
  3. Two thicker black wires and a thinner white wire, in a twist connector. Voltage detected. I'm assuming the two black are the power coming in/out of the room, and the white goes to the switch.
  4. One black wire. Voltage detected. I'm assuming it is coming from the other side of the switch.

I'm not familiar with knob and tube or older wiring, but were the hot and neutral wires both black colour, and separate (i.e. not in a single conduit/sheathing like standard 14-2 wiring today)?

My fan has 4 wires:

  1. Black (which I know needs to go to the hot in the ceiling, and powers the motor)
  2. Blue (which I know needs to go to the hot in the ceiling, and powers the light)
  3. White (which I know needs to go to neutral in the ceiling)
  4. Green (which I think I can't do anything with since there's no apparent ground wires in the ceiling)

Are you able to identify the 7 wires in there?

I'll most likely be calling an electrician to help here, but I'm still very curious to know the solution.

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  • Insufficient verifiable info. Do you have a gnd? Turn on and measure V to known earth gnd then if 0 measure ohms label the wires. Then try schematic tool here. However no current to load and line will also measure line voltage . You want to switch line, not neutral.. try DIY HOME group – Tony Stewart Sunnyskyguy EE75 Aug 23 at 19:28
  • The twist connector with two black and one white wire is a red flag that someone before you has messed up the wiring and/or violated code. Now it's not safe for a beginner to work with. And, noncontact detectors can fool you -- an open neutral (e.g.the loose white wire) can appear to have voltage. Get an electrician. – Mark Leavitt Aug 23 at 21:15
  • Can you post photos of the insides of the boxes involved please? – ThreePhaseEel Aug 24 at 0:04
  • @Mark Leavitt, can't a white wire be used for the wire coming from ceiling power into the switch, which then goes to the black wire from the switch to the black wire on the fan? Also I will be getting an electrician but not for another week, so was quite curious to understand the solution. – jordan Aug 24 at 1:05
  • @ThreePhaseEel it is at a different property which I won't have access to for a few days, unfortunately. So I tried to draw the picture as accurately as possible. – jordan Aug 24 at 1:06

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