Steel City 54151 NV Steel Octagon Box, 15.8 Cu In, 1/2 In

The 54151 NV is a 15.8 cubic inch octagon box. Box fill is calculated from that volume, so at 2.00 cu in per 14 AWG conductor that works out to 7 conductors, or 6 at 2.25 cu in for 12 AWG, before any deductions for devices, clamps, or a fixture stud. Grounds count as one conductor total, and a fixture-hickey or clamp deduction comes off the same 15.8 in3.

Go shallow only when depth forces it. The 54151 NV gives 15.8 cubic inches at just 1/2 inch deep, which suits a concrete ceiling, a furred-out soffit, or a retrofit over a joist where nothing deeper will seat. If you have the cavity, a deeper 4 inch octagon gives you more cubic inches for splices and devices. With 15.8 in3 you have room for a fixture whip and a couple of splices, not a multi-circuit junction.

Yes. A 4 inch octagon box like the 54151 NV uses the standard 2-3/4 inch on-center fixture mounting hole spacing that round and octagon ceiling boxes share, so typical lighting canopies and 4 inch round covers land on it. The box is 4 inches across, so any canopy at least that wide conceals it.

Steel, drawn construction, with a silver finish. A drawn steel box is a one-piece pressed shell rather than a welded or sectional one, and being metallic it can serve as part of the equipment grounding path with metal raceway, which a nonmetallic box cannot.

It is sold each, under manufacturer part number 54151 NV, so you can order exact counts rather than a full case. Property managers stocking a few for lighting repairs and contractors buying by the box both work off the same part number.