Steel City 4" Square Box, 1-1/2" Deep

The Steel City 4 inch square box is a 21 cubic inch box at 1-1/2 inches deep. Box fill is calculated from that 21 cubic inch figure, so for 12 AWG (2.25 cu in per conductor) you get nine conductor allowances, and for 14 AWG (2.00 cu in) you get ten, before deducting for devices, clamps and grounds. If the count comes up short, step to a deeper 4 inch square box or add a raised plaster ring, which adds its own marked volume.

No. The Steel City 52151 is a steel outlet box, 4 inches high by 4 inches wide by 1-1/2 inches deep with 17 knockouts, intended for dry interior work. For an exposed wet location, the Mulberry Royal Mountie is a 1-gang weatherproof outlet box in die-cast aluminum, and the Thomas & Betts 2IH3-1 Red-Dot is a 2-gang conduit outlet box with three 1/2 inch hubs. Those two are built around gasketed covers and threaded hubs rather than knockouts.

The Steel City 52151 is a standard steel outlet box and is not an explosionproof enclosure. For classified locations, Appleton's GRJ Series and GRJS Series are explosionproof malleable iron conduit outlet boxes, and the Appleton GRT75 is a malleable iron round conduit outlet box. Those use threaded conduit entries rather than the knockout pattern on the 52151.

Yes. There are 17 knockouts on the box, spread across the sides and the back, so you can bring conduit or cable in and out on multiple faces and still have a back knockout for a ground or a drop. That count is what makes a 4 square the usual choice for junction and feed-through points rather than a single-gang box.

Yes. At 4 x 4 x 1-1/2 inches it sits inside the 3-1/2 inch depth of a 2x4 stud bay with room behind it. Add a raised plaster ring sized to your wall finish to bring the device out flush and to reduce the opening to the gang count you need.

Yes. The box is sold as a bare box, each, with no cover included. Plan on a separate flat blank cover for a junction box, or a single- or two-gang raised plaster ring if you are mounting devices.

Steel is the choice where the wiring method is EMT or MC cable, because the metal box bonds the raceway and gives you a 21 cubic inch junction point with 17 knockouts. For nonmetallic residential cable work, a PVC box such as the Cantex EZ Series multi-gang residential outlet box is the usual pick since it needs no bonding and accepts NM cable directly. For a 240V range or dryer connection, neither applies, use a dedicated box like the Pass and Seymour P242RRD range and dryer box.

A range or dryer outlet is usually installed in a purpose-built box such as the Pass and Seymour P242RRD range and dryer box, which is a thermoplastic unit made for that receptacle. The Steel City 52151 is a general-purpose 4 inch square steel box, 1-1/2 inches deep with 21 cubic inches, so conductor fill for heavy appliance circuits is the limiting factor to check before substituting it.