I am in the process of installing a recessed light. The sticker on the light says a maximum of "4 No. 14 AWG through branch circuit conductors" are allowed in the box. Based on my box fill calculation, I should be able to run more and larger conductors. The box is sized at 21.9 in^3. Therefore assuming I ran 2 12 gauge conductors in and out, I'd only be at 9 (not including allotments for clamps etc.) Still, I think I would be well under 21.9 in^3. What governs here, the manufacturer's sticker or the NEC?
Thanks.

The mfg. sticker is always a conservative approach to capacity. That being said, in the event of a malfunction in which a fire was to start in the fixture, sure as hell that would come into play where an inspector for the insurance company was involved.

The sticker on the light says a maximum of "4 No. 14 AWG through branch circuit conductors"

What are "through branch conductors" as the manufacture defines. Sounds like 8 wires to me.

Unfortunately, they didn't define "through branch conductors" either on the unit or in their literature.

"Through Branch Circuit" wiring means wiring coming into the fixture as a source, and another cable leaving to go to another fixture.

Manufacturer instructions will always supercede the National Electric Code, as the NEC will refer to the UL Listing of products.

Okay, thank you.

I'm finally getting around to finishing this project. My question now -- does the daisy chain between two recessed lights count as a through branch conductor for the purposes of the box fill calculations given by the light manufacturer? Basically what I have is two recessed lights controlled by two three way switches on a 20 A circuit. So, I'm trying to run a 12-3 traveler which means I'll have a 12-3 cable entering and exiting each recessed light junction box, so, my understanding would be that the 12-3 cable does not count as a "through branch circuit". If that's the case, would standard box fill rules now govern? Thanks!

Sounds like you are making it more difficult than it has to be.
Tell me are you feeding the switch or are you feeding the light?

I'll make you a drawing. No reason to have to fight the fill in a can light box.

Power going into the switch. I do feel as though I am fighting, and losing. Thanks.

..

Thanks for the diagram. That's really helpful. I think option one will work fine and since the switches are close to one another, I won't have to use that much of the 3 wire cable.

You are welcome.

After thought.
Rereading TK definition of "through branch circuit" and thinking, it always helps to think. A through circuit would always involve at least 4 wires. Two in and two out. Four wires for each circuit times four circuits would be sixteen wires. Manufactures limit makes a lot more sense now. Always helps to think and to read what is actually written.

I guess where I'm still a little confused -- "4 No. 14 AWG through branch circuit conductors" seems like it would mean a maximum of 2 wires into the box from the power source and 2 wires out of the box to the next light or switch. Based on my understanding, it would mean that it would be impossible for this fixture to be wired as a three way since at a minimum there would be 3 wires in and 2 wires out. But, it doesn't seem logical that a manufacturer would make a light that can't be wired for a three way switch. I feel as though I must be missing something (as an aside, I am waiting to hear back from the manufacturer (Halo) for their take).

By TK's definition a " through branch circuit" is a circuit that comes into the box and goes out. That would be one cable coming in and one cable going out. To be a circuit the cable has to have two wires, a hot and a neutral. So one through branch circuit would have one cable with two wires or conductors coming in and one cable with two wires or conductors going out. That would be 4 wires or conductors for each "through branch circuit". Four conductors times four circuits is sixteen wires or conductors coming together in the box. That's a lot. I haven't figured it up but the NEC probably won't allow that many when you start counting grounds and other things.

I hope I'm not beating a dead horse, but I'm still hung up on the use of a "conductor" by the manufacturer. Your definition makes complete sense and is more logically than my conclusion, yet I'm stuck on the fact that the NEC defines a "conductor" as the individual wire and the manufacturer seems to be defining a conductor as the cable containing 2 wires (not including ground),

I think I am beginning to see what you mean. I guess I reading that as "branch circuits".

I think my solution is going to be to get out the sledgehammer and release some frustration on these lights that seem to just be poorly designed. Then, I'll go buy some recessed lights with boxes that can accommodate what I'm trying to do. :D

I bought new fixtures and now have a box that allows 8 12 AWG conductors (4 in and 4 out) so I should be good.