I just moved into a new house. We had 5 ceiling fan rough-ins done (2 light switches for the rough-in). So, the rough-in has 4 wires (grounding, white, black, red).

I've successfully installed two fans. In one room; however, we just can't get the fan working and I think it's the rough-in/switch. I triple checked the wiring of the fan, it was all done correctly. I also tried hooking up an LED light to the wiring. The light does not turn on or off when I use the switch. I tested the LED light on two other rough-ins and the light DOES work...Just not on this rough-in.

I have a cheap voltage detector. When I held it up to the black and red wires and had my wife flip the switch, the voltage detector DID go on and off, which is confusing me because that means the switches are working in feeding power to the wires, though I am not sure how much.

Does anyone know how I can troubleshoot the problem here? Even the LED light not working makes me think that it is something with how the builder did the wiring. I am not sure where to go from here.

  • When someone tells me they did it right and it is not working that is an extra charge. You may have a good switched hot as it sounds but if the neutral is open it won’t work. As @jack is asking is there really a measurable voltage there? Neutral to hot? You may see a voltage of 90v or less with a standard high impedance meter and an open neutral, it can also be a problem with the new fan. An actual volt meter can really be helpful. I would be testing for the voltage at the fan.
    – Ed Beal
    Jun 17, 2021 at 13:36

3 Answers 3


Possible open neutral circuit. You will need a volt meter to determine if there is any potential from hot to neutral. If not, then your lights and fans won't work there even though you have "voltage" present and (hopefully) indicated from hot to ground.

The next step would be to check the other end of that cable for a loose white wire.


Thank you all for the help. After checking both ends of the wire, and rewiring everything again. It turned out that one of the neutral white wires was not fully in the wire connectors. This meant that the white wires were not completing the circuit.

Once I stripped the wire a bit more and pushed it in further, everything started working again!


Since you're in a new home, invest in a multi meter so you'll know "how much".

With the power off, remove the switch plate and pull the switches out, turn the power back on and test for voltages and correct wiring. There should be always hot on both switches, probably pigtailed to both switches and switched hot, black and red, from each switch and neutrals connected together. When reinstalling the switches, turn the power off until everything is put back to normal.

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