Rough'ed a bath a while back, got called for finish with customer provided lighting. The customer wanted excact placement of some vanity lighting. (All of which landed on stud work... So 3 3/0 pancakes.) So today, I go and get the lights out of the box, and said to myself, "Wow, that's a small canopy? How does that mount? That can't be legal. It mounts to a 1 gang box?"
Built for the exeption, at 5 1/2 lbs!
314.27 Outlet Boxes.
(A) Boxes at Luminaire (Lighting Fixture) Outlets. Boxes used at luminaire (lighting fixture) or lampholder outlets shall be designed for the purpose. At every outlet used exclusively for lighting, the box shall be designed or installed so that a luminaire (lighting fixture) may be attached.
Exception: A wall-mounted luminaire (fixture) weighing not more than 3 kg (6 lb) shall be permitted to be supported on other boxes or plaster rings that are secured to other boxes, provided the luminaire (fixture) or its supporting yoke is secured to the box with no fewer than two No. 6 or larger screws.