Steel City 36115 C30 Steel Round Box, 3-1/4 In, 4 Cu In

Four cubic inches is tight. Box fill math gives 2.00 cubic inches per 14 AWG conductor and 2.25 per 12 AWG, so a 4 cubic inch box holds two 14 AWG conductors, and the internal cable clamp counts as one more conductor volume. In practice the 36115 C30 is a fixture-connection box for a single cable, not a splice or junction point for multiple runs. If you need room for several conductors plus device, go to a deeper 4 inch round or an octagon box.

Depth is the deciding factor. At 1/2 inch deep the 36115 C30 is a pancake-style box, which is what you use when there is no room above the ceiling or you are mounting on the face of a joist or a concrete deck. With almost no interior depth, all wire splicing has to happen inside the fixture canopy. If you have open joist bays, a deeper box gives you working room.

The Steel City 36115 C30 is a drawn steel round box, 3-1/4 inches in diameter with 1/2 inch depth and 4 cubic inches of volume, intended for lighting outlets rather than fan support. For a fan-rated opening, the RACO 295-1 is a 4 inch round fan-rated steel ceiling pan in THE INSIDER series, and the Pass & Seymour Reiker drop ceiling fan and fixture support box is built for fan and fixture support as well.

Clamps are built in. The 36115 C30 ships with an internal cable clamp and 1/2 inch knockouts, so you can land NM cable without buying a separate connector. If you are running conduit or armored cable, you would still use the appropriate 1/2 inch fitting at the knockout.

Steel, like the 36115 C30, is what you use with metal raceway or armored cable where the box has to be part of the equipment ground path, and where a shallow drawn profile is needed. Nonmetallic boxes such as the Allied Moulded 9304 fiberglass reinforced or the SB-CB Sliderbox polycarbonate ceiling fixture support boxes are used on nonmetallic cable systems and where corrosion or isolation matters. Those Allied Moulded units are also built as fixture support boxes, which the shallow steel pancake is not.

The 36115 C30 measures 3-1/4 inches across, so it takes a 3-1/4 inch round pancake cover or a fixture canopy of that diameter or larger. Standard 4 inch round covers will not line up with its mounting holes.

The Steel City 36115 C30 is steel. If a non-metallic box is wanted instead, the Allied Moulded 9304 is a fiberglass reinforced ceiling fixture support box, the Allied Moulded SB-CB Sliderbox is polycarbonate, and the Allied Moulded PC244OW is the FlexBox series ceiling fixture support box. Non-metallic boxes do not provide the metal raceway bonding path a steel box does, so confirm the wiring method first.

The Steel City 36115 C30 holds 4 cubic inches in a 3-1/4 inch by 1/2 inch deep drawn body, which suits a shallow lighting outlet with few conductors. For more room, the deeper ceiling fixture support boxes are the alternatives: the Allied Moulded 9304 fiberglass reinforced box, the Allied Moulded SB-CB polycarbonate Sliderbox, and the RACO 295-1 4 inch round steel ceiling pan.

It is sold each, so you can order the exact count you need for a job rather than a full carton.

Drawn construction. The 36115 C30 body is formed from a single piece of steel rather than assembled from welded sections, so there are no seams at the corners for the shallow 1/2 inch profile. Country of origin is Canada.