Oklahoma Electrical Practice Exam

In the scenario provided, what is the smallest size device box allowed by NEC for certain wire configurations?

1. 12 cubic inches

2. 18 cubic inches

3. 24 cubic inches

4. 30 cubic inches

The correct answer is: 18 cubic inches

The National Electric Code (NEC) stipulates specific requirements for the sizing of device boxes based on the number of conductors, devices, and other factors to ensure safety and functionality. For certain wire configurations, particularly those involving multiple conductors or added devices, the minimum size of a device box is crucial to prevent overheating and to facilitate easier wire management. In many standard scenarios, a device box needs to be at least 18 cubic inches, which provides sufficient space to accommodate the conductors and devices that will be housed within it. This size ensures there is enough room for wiring connections, helps prevent crowding, allows for heat dissipation, and aids in conforming to installation standards. While other sizes may be applicable under different specific conditions or configurations, 18 cubic inches is a commonly accepted minimum requirement for various residential and commercial setups, making it a standard choice according to the NEC guidelines.