Does this j-box follow NEC electrical code

junction-boxnec

I'm considering buying the following product for a security floodlight install:
Arlington 8141-1 Vertical Siding Lamp Mounting Kit with Built-in Box for 1/2 Inch Vertical Siding LAP. It seems to get great reviews, but I don't understand how this can possibly follow code. It features a round, 4in diameter x .5in deep j-box. In the simplest case, it would require six wires to connect a fixture at the end of the cable run (three from the NM cable, three from the fixture). However, six 14-gauge wires would require a 4in round j-box that is 1.25in deep according to NEC.

Can someone please explain to me why this j-box is acceptable or not? Full disclaimer, I'm a total noob at electrical so it's entirely possible I'm just not understanding something properly. Thanks!

Best Answer

ecmag.com's interpretation of 314.16(B)(1) Conductor Fill:

There is an exception under the conductor-fill provision that pertains to luminaire (fixture) conductors. An equipment-grounding conductor or four or fewer luminaire (fixture) wires smaller than 14 AWG, or both, entering a box from a domed luminaire (fixture) or similar canopy and terminating within that box, can be omitted from box-fill calculations. Under certain conditions, up to four luminaire (fixture) conductors and one equipment-grounding conductor can be installed but not counted in the box-fill calculation. The conductors must be 16 AWG or smaller and must enter the box from a domed luminaire (fixture) or similar canopy.

I always wondered why the wires on lights are so flimsy; that's why, so you don't have to count them in box fills.

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