Ceiling fan rough-in wiring suggestions

Electrical rough-in on our new home is almost done, and I'm wondering if I should have done something different for ceiling fans with light kits.

Power for all ceiling fans goes to a wall switch box first, i.e., ...

Line in -> junction box for fan control -> ceiling fan box.

12/3 + ground Romex between wall control junction box and ceiling fan box. The wall control junction boxes are all two-gang. Each junction box location has to control three devices in the room in which it is located... a ceiling fan (on/off/speed), the ceiling fan lights (on/off/level), and a "string" of recessed lights (on/off/level). That's easy to do if I don't care about HE controlling the ceiling fan and it's light kit.

The goal is to have all three devices controllable by physical switches and HE. My preference is z-wave, but zigbee and wifi are acceptable.

No idea what fans will be used, but must be multi-speed (e.g., three speed) or variable speed. My preference is a "non-smart" fan. Would also rather stay away from fans that have their own remote controls.

Due to framing requirements, the wall junction box in the primary bedroom cannot be expanded to three-gang.

I'm fine with having a "smart dual dimmer switch" (if there is such a thing) to control the recessed lights and fan light kit, and a separate smart fan control for the fan. In other words, the same device doesn't have to control the fan and the fan light kit.

Can the 12/3 romex from the switch box to the fan box handle this scenario? Should I instead run two 12/2's? Any other suggestions?


Hi Justin,
I recommend using 14/3 wire to connect your switch box to the ceiling fan outlet. 12/3 is just too stiff/bulky when you are trying to cram multiple switch modules in the same switch box. Use the deepest switch boxes that are available. Leviton makes a ZW4SF-1BW Decora Smart 4-Speed Fan Controller with Z-Wave 700 Series technology. This seems like the easiest and most user friendly option. Unfortunately, I have only used Leviton Dimmer & On/Off light switches (expensive but well made). I have had good luck with the Zooz Zen77 dimmer switches for lighting since they are compatible with existing 3/4-way switches.

This and, I only use #12 for all outlets, lighting is #14. There is no benefit to using #12 for lighting and as mentioned by @user6485 it becomes difficult to lay in the wires with #14, #12 is worse.

You might ask your contractor to put in extra deep boxes for the wall switches (unless that ship has already sailed).

There are a number of dual-purpose switches out there meant for fans with lights. Both "dumb" on/off (for each) versions, dimming/speed versions, and "smart" versions. These will only use one area of your double gang boxes. For example, I have one of the (now discontinued) Inovelli Red-series Fan/Light switches and it has been working quite well for me to control the fan/light I have in my hobby room/office.

But personally, I would always recommend having a spot for EACH thing, just in case, as the worst thing in that scenario is you put in a blank filler plate on one spot. So in your case, it would be a triple-gang box per room (except the bedroom obviously as you said it would not fit). It is a bit of future proofing (who is to say you will never want to add something else in the room controlled by a switch) as well as providing plenty of working space in the box (also agree with the deep boxes). This also allows you to have a single switch that controls a single thing. Generally cheaper and easier to deal with. For example, each of our 3 bedrooms have a fan/light combo in them. We have a dimmer light switch first (for the lights) and a separate switch for the fans. All of them are z-wave. It helps for automations regarding vacation (the lights can go on at reasonable times for the "lived in" view) and the fans can start up in the evening on hot days before we go to bed or shut off if forgotten in the mornings.

I do not have any triples like you are doing but I do use the built-in Mirror app to mirror what happens with the light's dimmer to a smart bulb in the room. So the bulb goes on/off, and dims at the same levels as the lights on the fan. Not sure if that might be an applicable alternative to a switch for your LED strips.

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The two gang boxes are 47 cubic inches, so up to 20 #12 equivalents. The most any of the boxes will have is line in, line out, 12/2 for recessed light switch leg, and 12/3 for fan/light combo switch leg. I think that adds up to 14 #12 equivalents, so the box shouldn't be too full.

Not sure why, but all new homes (in at least the last 10 years) in this area use 12/2 with ground Romex for general purpose lighting and outlet circuits, protected by 20A breakers. Lighting and outlets are usually mixed on the same circuit, so dropping down to #14 for lights would require dropping down to 15A breakers for those circuits. Doing that would possibly require redesigning those circuits.

I plan on having the electrician use #12 stranded for all pigtails in the boxes to make it easier to install devices.

Also, I just remembered that the recessed lights in the primary bedroom are on a 2-way switch setup.

A couple of general comments:

First, the box where the switches are located is usually called a 'wall box.' IME, a 'junction box' is a specific thing that only splices two or more sets of wires together, and has no devices in it. (Not that a smart house user has never put a device in a junction box, but the average electrician won't usually do that in their normal work.) I say that in case it lessens any confusion with your builder or electrician.

Second, agree with the note to use 14ga wiring for lighting. I have a couple of runs where someone inexplicably used 12ga for lighting and it's a total pain.

As far as control, since you have 2 gangs available in the wall box and three sets of loads (fan, fan light, and can lights,) you are going to have to compromise or get creative somewhere.

(Edit: I misread the quote.) I wouldn't do that. See the second paragraph below.

I would tie all the lights together and use two devices, a fan speed control in the wall and a single dimmer/switch controlling both the fan lights and the can lights. It is probably the most straightforward and easy to do. Your 14/3 wire to the fan, then split the lighting hot off to the can lights with some 14/2. My master bedroom is wired this way, and there are no issues. (Other than the minimum dimming level being different, but that's easy to work around.)

I, personally, would tie the light strings together as opposed to looking for a 'double dimmer.' That will -IMHO- cause issues down the line when it fails or technology changes and you look for a new device. Those are fairly esoteric, and you're left hoping a manufacturer makes one when you need it. Obviously, single-load dimmers will be ubiquitous for as long as your house is standing.

One final thought... I mentioned that my master bedroom was wired with the fan lights and the can(less) lights strung together. It works fine, the wiring is straightforward, and the control device is simple as well. That said, I wish I hadn't done it. I wish I had gone with a fan with no lights and added more can(less) lights to make up the difference. It's not the end of the world, or the worst decision I've ever made, but I don't like having two different physical light types in the same room. (Again, it's not terrible, but removing the fan light kit and adding more can lights is on my 'home improvements' list, but down toward the bottom.)

FYI. The with the widespread use of LED lighting and the energy efficiency of modern electrically powered devices, the 2023 NEC has some interesting changes. NEC Section 210.23, "Permissible Loads, Multiple-Outlet Branch Circuits", grants permission for 10-amp branch circuits to supply one or more of the following loads: 1. Lighting outlets 2. Dwelling unit exhaust fans on bathroom or laundry room lighting circuits 3. Gas fireplace units supplied by an individual branch circuit. #14 wire is the minimum cable size permitted for these loads.

Consider this: One 15A/120V [#14 wire gauge] lighting circuit loaded at (80%) will deliver 1440 Watts. Most LED bulbs are less than 10W, therefore one 15A circuit can supply 144 LED light bulbs (most likely the whole home). Using #12 wire for lighting loads is a bit overkill :slight_smile: With the cost of copper and labor these days, the benefits of #14 wire makes since.

For future residential electric projects, I plan on using #14 wire for all rooms except the kitchen, laundry, garage(s), workshop, outdoor outlets. To be conservative, each room would have their own 15A branch circuit. Of course, Kitchen area will be served with multiple 15A or 20A branch circuits as required.

I share this information to help others. I realize you are dealing with existing wiring and your current wiring strategy seems reasonable. I also agree with the other useful suggestions in this posting.

Disclaimer: Check with your local City Building Inspection Department and since they sometimes have different interpretations of the current NEC.

Talked to the builder and he said he can make room for a 3-gang box, so we will have a dimmer for the recessed lights, a dimmer for the fan light, and a switch for the fan speed control.

Thanks for the comments.