Electrical Boxes & Covers

Lumera Electric stocks electrical boxes and covers for device, junction, and floor applications. The range spans new-work and old-work boxes, metal and PVC, single- through four-gang, plus weatherproof boxes, NEMA enclosures, mud rings, blank covers, and in-use covers. Source boxes and covers from Orbit, Arlington, Lew Electric, and Westgate, with trade pricing and bulk-quote support.

Electrical Boxes & Covers

What's the difference between a junction box, device box, and 4-square box?

Each box has a job. A junction box houses wire splices behind a blank cover, with no device. A device box holds a switch or receptacle in a wall. A 4-square (1900) box is a deep multi-purpose box that adapts to either with a mud ring.

  • Junction box — wire splices only — closed with a blank cover
  • Device box — holds a switch or receptacle — single- through four-gang
  • 4-square (1900) box — deep multi-purpose box — adapts with a mud ring

What's the difference between a new-work and old-work box?

Mounting method sets the type. A new-work box nails or screws to a stud before the drywall goes up. An old-work (remodel) box installs in finished drywall and clamps to it with wings or spring ears — no stud access needed. Both come in metal and PVC.

What size electrical box do I need?

Box size follows NEC box fill. Add the conductors, devices, and clamps inside, then choose a box with enough cubic-inch capacity. A standard single-gang box holds 18 to 22.5 cubic inches; deep and 4-square boxes hold more. Overfilling a box violates code and traps heat.

What is a mud ring (plaster ring)?

A mud ring, also called a plaster ring or device ring, is a raised cover that mounts on a 4-square or masonry box. It adapts the box to hold a device and brings the opening flush to the drywall surface. Rings come in 1/2-inch to 1-1/4-inch raised depths and one- or two-gang.

What box and cover do I need outdoors?

Outdoor boxes require a weatherproof rating and a gasketed cover. A while-in-use (bubble) cover keeps a cord-connected device protected from rain, as code requires in wet locations. A blank or flip-lid cover suits damp, protected spots. Match the box and cover to the wet or damp location rating.

Jump to what you need: Electrical Boxes for device and gang boxes, Junction Boxes for splice enclosures, and Floor Boxes for in-floor power. For exterior work, see Weatherproof Boxes and Weatherproof Covers. Mud rings, plaster rings, and blank covers are in Electrical Box Covers & Rings.