What should be included when calculating space in a box for conductors?

When calculating the space in a box for conductors, it is essential to include all devices and any splices present. This is because each device and any splices contribute to the volume that must be accounted for to ensure that the box can accommodate all conductors safely.

According to the National Electrical Code, proper box fill calculations are necessary to prevent overcrowding, which can lead to overheating and pose a fire hazard. Each conductor, device, and splice has a specific volume allowance, and it's critical to consider them all to achieve compliance with safety standards. The calculation helps ensure that the box can safely house the conductors without risking thermal issues or electric failure.

Including only the type of circuit or the color of the wires does not contribute meaningfully to the volume needed for safe conductor placement, and the length of conduits, while relevant in some contexts, is not a factor in the box fill calculation as defined by the NEC.