What is the purpose of counting each conductor that passes through a device box during fill calculations?

Counting each conductor that passes through a device box during fill calculations is essential to ensure proper sizing of the box. The National Electrical Code (NEC) specifies requirements for box fill to prevent overheating and electrical hazards. Each conductor, as well as devices, fittings, and any additional components within the box, contributes to the total fill volume and must be accounted for to avoid exceeding the box's capacity.

When properly sized, the box can accommodate the conductors without risking damage or creating a fire hazard due to overcrowding. This careful consideration of fill calculations contributes to a safe and effective electrical installation by providing the necessary space for conductors and ensuring ease of access to connections. If the box is undersized, it can lead to complications such as poor connections or insulation damage, creating further safety issues.

In contrast, the other options, while relevant in their contexts, do not directly address the primary reason for counting conductors in box fill calculations. Safety compliance, voltage drop considerations, and installation facilitation are important, but they are secondary to the necessity of proper box sizing.