Chapter 2, Problem 1RQ

Name the size of machine screw that is used to secure switches and receptacles to device boxes. (Objective 2-8)

To determine

The size of the machine screw that is used to secure switches and receptacles to device boxes.

Explanation of Solution

Introduction:

Metal device boxes are widely used in residential wiring, even though non-metallic device boxes have become the best choice across the country. The standard metal device box has a $3\times 2$ -inch opening and can vary in depth from $1\mathrm{½}$ to $3\mathrm{½}$ inches. The most common metal device box used is the $3\times 2\times 3\mathrm{½}$ -inch box because it can contain several wires and devices.

The holes are designed to mount the device and accommodate screws of a switch or receptacle andlock the device to the box. The holes are tapped for a $6-32$ screw size. At the bottom of the box, there is a tapped hole that accommodates a $10-32$ grounding screw. This screw's shapeis hex headed and green in color, and its function is to attach the circuit's equipment grounding conductor to the metal box.

Conclusion:

Thus, the size of the machine screw that is used to secure switches and receptacles to the device boxes is $6-32$ screw size.