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Went to look at a ceiling box to install a fan, and I'm a little confused as to the wiring for the light now. Currently, the light tends to flicker depending on how tightly the globe is screwed in (for whatever reason, and yes it's a new bulb) and I'm assuming there's a problem somewhere. Excuse my very bad schematics, but I thought it might help explain things.

Right now, the ceiling box has cable coming in on two sides with hot and neutral wires, and another with hot, neutral, and ground coming up from a wall switch. It's currently wired like this:

current light wiring

The current light has two hots and two neutrals. The neutrals are wired together, the hot is tied into the hot from the switch (right side of the diagram), and the ground is screwed onto the mounting bracket for the light. The hot from the cable on the left side is tied into the neutral from the cable on the right and the hot from the switch. The neutral from the cable on the left is tied to the neutral from the switch. The switch ground wire wrapped is around a screw in the ceiling box. Is this correct? Should the neutrals on the light be tied in to anything in the box, rather than to each other?

Now, the second part- to put a fan in, I know I need to install a support, a new box, and change the current switch from a dimmer to a toggle. What I'm wondering, however, is given that the wiring available will look something like this (see poorly drawn schematic below), how do I tie everything in?

ceiling fan wiring

Thanks in advance for your help! I'm decent enough to change fixtures and plates out, but I wasn't expecting to see this and given that the light already has flickering issues I don't want to cause any trouble.

  • Edit: updated the first "diagram" and corrected the text to be more accurate. – sswyryt Jun 10 at 13:42
  • Do you just want a fan here, or a fan with a light? – ThreePhaseEel Jun 10 at 23:06
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Most ceiling light boxes are not equipped to handle the weight and vibration of a fan. Sounds like you are on top of this.

The black wire coming from the odd cable to the lamp is your switched hot from the switch. It's partner white wire is not a neutral at all. It is an always hot going to the switch. That wire is supposed to be marked with tape on both ends to indicate that it is not a neutral wire. You may want to Mark it in this box, so that you are clear on what it does.

The clump of wires that is entirely white, is actual neutral. You will need that for your lamp, so put a pigtail in that bundle.

As far as wiring in the new fan, it will be nothing new. The new fan will wire in exactly as the lamp did. The new Switch will connect to exactly the same wires as the old switch. Note that if the new Switch requires a neutral it will not be available and you cannot use it.

Also, if the new Switch needs two separate wires to control fan and light independently, those are simply not available in your setup. You will need to run a new /4 cable between the two boxes.

  • Thanks, Harper. Is it typical to be able to find a toggle switch that doesn’t need a neutral? – sswyryt Jun 12 at 17:58
  • Plain human powered switches don't need neutrals. Most smart switches do. Most. – Harper Jun 12 at 18:36

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