Steel City 54561 Octagonal Box

The 54561 is a 41 cubic inch box, which is a large volume for a 4 inch octagon and gives you real room for box fill when several cables land in one ceiling outlet. Work your fill from the NEC table for the conductor sizes and the devices, clamps and grounds in the box against that 41 cubic inches.

The 54561 measures 4 inches in diameter by 3-1/2 inches deep (101.6mm across), so it needs a full 3-1/2 inch cavity behind the finished surface. In a 2x4 stud or joist bay that is tight, 2x6 framing or an open ceiling plenum is where this depth belongs. If you only have shallow depth above the ceiling, use a shallower octagon instead.

Two knockout configurations are offered: 1/2 and 3/4 inch (part 54561 1/2 3/4) and 3/4 and 1 inch (part 54561 3/4 1). Pick by the trade size of the raceway or connectors you are landing. The 1/2 and 3/4 version suits typical branch circuit EMT and flex runs; the 3/4 and 1 version is for heavier feeds or larger conduit. Order the part number, not just the model, or you can get the wrong combination.

Yes, a 4 inch octagon is the standard ceiling outlet box for luminaires, and this one is drawn steel with a single outlet. Fixture canopies and 4 inch octagon covers mount to the box ears on the standard 2-3/4 inch fixture screw centers. For a paddle fan you need a box specifically marked as fan rated, not a general purpose octagon.

Drawn means the 54561 body is formed from a single piece of steel rather than welded from panels, so there are no seams at the corners to open up when the box is hammered onto a joist or when conduit is pulled. The finish is bare silver steel, which is what grounds through the box and the ground screw.

The 54561 ships 20 boxes to a carton. For a multi-family or build-out job where every ceiling outlet uses the same deep octagon, ordering in carton multiples keeps the counts clean on the floor.