A four-square box is a 4 by 4 inch steel box, 1-1/2 or 2-1/8 inches deep, with knockouts on every side and the back. With a mud ring it becomes a roomy device box, and with a flat blank cover it serves as a junction or pull point. The 2-1/8 inch deep version holds 30.3 cubic inches, more than twice a gem box, which is why commercial jobs use it nearly everywhere. Crews also call it a 1900 box, after a catalog number.
Every receptacle on this job is a deep four-square with a single-gang ring, no gem boxes in the walls.
Also heard as
- 1900 box
- 4S box
- 4-square
- square box
Related terms
Mud ring
Raised cover that screws onto a square box and gives a flush opening for devices in drywall or plaster.
Four-eleven box
Square steel box 4-11/16 inches on a side, the step up from a four-square when #10 wire or big receptacles fill it.
Gem box
Single-gang metal device box with removable sides, so several can be ganged together for a row of switches.
KO
Knockout: a partly punched disc in a box or panel that is removed to make a hole for a conduit or cable fitting.