B-Line Eaton series Type 3/3R junction boxes, 18" height, 6" length, 12" width, 3 and 12, Screw cover, WPSC enclosure, Surface mounted, Medium single

It measures 18 inches high, 12 inches wide and 6 inches deep, which is where the 18126 designation comes from. The 6 inch depth is the number that usually decides the job: it sets how much room you have behind the cover for wire bending space, terminal blocks or a small DIN rail once conduit hubs are landed. Shipping weight is 14.3 lb.

It is surface mounted using external mounting feet welded to the back, so all fasteners stay outside the enclosure and nothing breaches the gasketed interior. The feet also stand the box off the wall slightly, which helps on damp masonry or exterior walls. Anchors are sized to your substrate and are not supplied with the box.

It ships as a blank enclosure, so you punch or drill your own conduit openings where the run lands. That is standard for a gasketed 3R screw cover box: any factory knockout would be a leak path. Keep the penetrations on the sides or bottom and use rain-tight hub fittings to preserve the Type 3R rating. The body is 16 gauge carbon steel, so a standard hole punch handles it cleanly.

Screw cover. The 18126 WPSC uses a flanged cover fastened with gasketed screws, not a hinge and latch. That is fine for a junction or pull box you open rarely, and the all-around screw pattern gives you even gasket compression. If technicians will be opening it routinely for testing or resetting devices, choose a hinged-door enclosure instead, because a 20 screw cover gets old fast and the gasket suffers from repeated removal.

Painted carbon steel in ANSI 61 grey, the standard gear grey that matches most switchboards, panels and control enclosures. Painted steel is suitable for general outdoor and industrial exposure. In a coastal, chemical or washdown environment, specify a stainless or non-metallic 4X enclosure instead, since paint over carbon steel will eventually rust at scratched penetrations.