What is the smallest standard size metal box that accommodates a single 1/2" romex connector and additional wiring components?

The smallest standard size metal box that can accommodate a single 1/2-inch Romex connector along with additional wiring components is 3.5 inches deep. This size provides sufficient volume to comfortably fit the connector and allows enough space for the conductors and any splices or devices that may be housed within the box.

In the National Electrical Code (NEC), when determining box size, considerations include the number of conductors entering the box, any devices or hardware that will be installed, and associated wiring connections. The 3.5-inch deep box not only provides the necessary volume for the Romex connector but also complies with the NEC's requirements for wire fill, preventing overcrowding which could lead to overheating issues or difficulty in making proper connections.

Choosing a shallower box, like a 2-inch deep box, would likely not provide enough capacity for all components, potentially making it non-compliant with the NEC requirements for safe electrical installations. Similarly, opting for boxes that are deeper than 3.5 inches, such as 4.5 or 6 inches, would exceed what is necessary for a single Romex connector, adding unnecessary bulk and complexity to the installation without any added functional benefit.