I have 3 hall luminaires controlled by a 4-way switching system. The electrician elected to run 14-3/G NM too all the fixtures. The most distant one is mounted on a round 4 inch x 1/2 inch pancake box. The capacity is marked 6 cu in. The red lead is in the box, but it is capped with a wire nut and not otherwise used. Does it count for 2 cu in like the black and white leads or does it count for 1 cu in like the ground because it is 'dead.'
The manufacturer suggests that the luminaire can be installed using only the central 1/8" IPT hole in the crossbar as long as the 1/8" nipple carries a lock washer and nut to fix it to the crossbar and a lock washer and nut secure the fixture to the nipple. Clearly the electrician had difficulty using the matching round head machine screws that can be installed in the threaded hole in the crossbar and the matching hole diagonally opposite it. Getting all 3 supports to line up is challenging.
Can I use only the nipple and meet code?
Are the missing knockouts a violation?