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I have two rooms each with:

  1. LED lights connected to a dimmer switch
  2. Ceiling fan with integrated LED light connected to an on/off switch

My objective is to have the light in the ceiling fan to be controlled by the dimmer switch. The fan has a separate wire for the fan and one to control the integrated LED. All the switches, dimmers, and fans in both rooms are the same make and models.

In room 1, I used a 14/3 wire to the double-gang box with the switches and used the red wire to go from the LED light wire in the fan to the dimmer. All works well. This is in the first diagram in the image below.

In room 2, the dimmer switch and on/off switch are in separate boxes, due to how the studs are laid out (double-gang won't fit by door entry). So from the ceiling fan, I ran one 14/2 to the dimmer switch for the light control and one to the on/off switch for the fan control.

For room 2, all works well, but when I start sliding the dimmer for the lights up and down, it trips the breaker. When I disconnect the LED light control from the 14/2 wire in the fan, then I have no trips. I even removed the LED fixture feom the ceiling fan, and still trips. I replaced the ceiling fan with the same model again, and same thing happens.

Here's the layout and the specific components, any thoughts?

enter image description here

I haven't Tried Configuration 3 yet:

enter image description here

Here's where we are after trying all the configurations I could think of:

enter image description here

Components:

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  • I take it you have both the fan and light wires connected to 120VAC right now? Dec 23, 2023 at 22:22
  • Yes. I installed a QO154M200PC just 4 months ago, and the QO115PAFGF and QO120PAFGF have been tripping with the 5 ceiling fans since then, so trying to handle that now.
    – isaacco
    Dec 24, 2023 at 1:31
  • I presume the existing power feed comes in at the switch box, no? Dec 24, 2023 at 4:06
  • 1
    Tried a few things, with no luck: (1) Completely replaced wires, (2) Replaced Switches, (3) Replaced Fan, (4) Changed wiring configuration, (5) Replace ground wire in ceiling mount, (6) Remove Debri between ceiling mount and electrical box, (7) Tighten/Loosen ceiling mount, (8) Change Breaker, (9) Removed LEDs from Dimmer and only left fan light connected
    – isaacco
    Dec 30, 2023 at 3:54
  • 1
    @isaacco -- have you used the diagnostic steps for your breaker to figure out why it's tripping? Dec 30, 2023 at 5:00

2 Answers 2

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According to the installation manual, this fan, as is very common, has:

  • Black wire for fan power
  • Blue wire for light power
  • White neutral
  • Green ground

With 14/3, everything is fine. But with 2 x 14/2 you are splitting the neutral. That violates the electrical code, because all currents must be equal/balanced in a cable. The electricity doesn't "know" whether to travel down the fan switch neutral or the light switch neutral.

With a GFCI you would almost always instantly get a breaker trip, because the odds of the current being balanced in each 14/2 cable at any given time is pretty much zero. AFCI generally is not as sensitive to this imbalance (as I understand it, some earlier generations of AFCI did function as a limited GFCI as well, but were not rated as a GFCI). My hunch is that because modern LED-compatible dimmer switches do some funny things to the power to make things work that combined with the splitting of the neutral you end up with a mess that the AFCI decides is not a good thing and trips.

While there may be some other solution that solves the AFCI problem, anything short of a 14/3 cable (or equivalent wires in conduit) will not solve the electrical code problem. So 2 x 14/2 is simply not an option here, and in fact the AFCI may have saved you from future troubles.

One solution, of course, is to use the remote kit. Some people love them, and I think the manufacturers really love them because at the cost of a few $ of hardware they allow anyone with an existing ceiling light (light only, no extra wire to run a fan) to install a combination light/fan. But the problem is that a remote requires use of the remote. If somebody made a permanently installable (so no batteries, compatible with other home automation, etc.) compatible single-gang remote-compatible fan/light switch, it would sell well. In fact, I wouldn't be surprised if somebody has already done that - but I have no idea.

The other solution is to find a single gang combination dimmer and fan control, and that is easy enough to find. For example, the Lutron from Amazon (and also available at Home Depot and other locations):

Lutron dimmer and fan control

Replace one 14/2 cable and switch with 14/3 cable and this combination switch and you're all set. If you have no use for the other switch, either cover it with a blank plate or install an extra "convenience" receptacle.

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  • I have that Maestro switch, but decided to keep everything on Caseta for the automation, especially with little kids leaving lights on everywhere. If you look at configuration 2 (the 3rd diagram) that uses two 14/3 wires. Even if I disconnect the LED lights and only use the dimmer for just the fan light, it trips. Any thoughts on that?
    – isaacco
    Dec 31, 2023 at 21:28
  • That's because the problem is not the "other" lights. The problem is splitting the neutral between fan (notor) and light (the one with the fan). Dec 31, 2023 at 21:31
  • I added a diagram for configuration 3, with the junction box. Would that work?
    – isaacco
    Jan 1 at 3:53
  • The only way to keep everything balanced in every cable is (basically) if everything is in one box. I don't think it is legitimate to do this in 3 separate boxes. Jan 1 at 4:13
  • @isaacco -- do both the dimmer and speed control require neutral, or can one get by without it? Jan 1 at 6:28
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It was the dimmer make/model. I replaced the DVRF-6L with a PD-5NE which handles the electrical phase current differently.

The weird thing is the total loads are way below what's needed for the DVRF-6L (maybe 20% of the capacity).

This also solved it for a few other circuits in the past.

The other rooms with the DVRF-6L, which have the same exact loads, have tripped once or twice before. May have to replace those switches.

Overall, DVRF-6L should be taken off the market.

Additional notes: The new (DVRF-6L) uses 120V FORWARD PHASE w/ max 150w Dimmable LEDs, while the old one (PD-5NE) applies 120V FORWARD OR REVERSE PHASE w/ max 250w load. Oddly, reverse phase is newer and the older PD-5NE handles 100w more load. Check the prices, the PD-5NE still costs more, sometimes substantially more (over 20-50% from what I've observed). For AFCI breakers, its recommended to use reverse phase, the way they are designed to handle the current. Yet, in AFCI document note for the DVRF-6L, even the load center and breakers are mentioned for best results, and I checks all the boxes. Its a mess.

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  • 2
    That's very curious that switching from a leading-edge to a trailing-edge dimmer fixed the problem Jan 13 at 17:30
  • 1
    The new (DVRF-6L) uses 120V FORWARD PHASE w/ max 150w Dimmable LEDs, while the old one (PD-5NE) applies 120V FORWARD OR REVERSE PHASE w/ max 250w load. Oddly, reverse phase is newer and the older PD-5NE handles 100w more load. Check the prices, the PD-5NE still costs more, sometimes substantially more (over 20-50% from what I've observed). For AFCI breakers, its recommended to use reverse phase, the way they are designed to handle the current. Yet, in AFCI document note for the DVRF-6L, even the load center and breakers are mentioned for best results, and I checks all the boxes. Its a mess.
    – isaacco
    Jan 14 at 4:54

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