Final answer:
The number of conductors that can be legally installed in a 4-inch square box, 2 1/8 inches deep, depends on the specifications and codes set by local building authorities. As a general guideline, the National Electrical Code (NEC) provides tables and guidelines to determine the minimum box volume required for different wiring configurations.
Step-by-step explanation:
The number of conductors that can be legally installed in a 4-inch square box, 2 1/8 inches deep, depends on the specifications and codes set by local building authorities. However, a general guideline is to follow the recommendations of the National Electrical Code (NEC).
According to the NEC, the maximum number of conductors allowed in a square box is determined by the box's volume, which is calculated by multiplying the interior dimensions and depth of the box. For a 4-inch square box that is 2 1/8 inches deep, the volume would be 4 * 4 * 2.125 = 34 cubic inches.
The NEC provides tables and guidelines to determine the minimum box volume required for different wiring configurations. For example, if you are using nonmetallic sheathed cable (NM) with 14 AWG wires, the NEC specifies that you would need a box with a minimum volume of 2.00 cubic inches per conductor. Therefore, in a 4-inch square box that is 2 1/8 inches deep, you could legally install up to a maximum of 17 conductors (34 cubic inches / 2.00 cubic inches per conductor).