When determining conductor fill at device boxes, how should branch-circuit conductors that pass through the box without splicing be counted?

In determining the conductor fill at device boxes, each branch-circuit conductor that passes through the box without splicing must be counted once. This approach adheres to standard practices for ensuring safety and compliance with electrical codes. The reason for counting each conductor only once is to maintain clear guidelines for safe wiring practices without overestimating the conductor fill.

This is important because electrical boxes have specific volume allowances based on the size and number of conductors to prevent overheating and ensure adequate space for safe installation. By counting each conductor only once, it facilitates accurate calculations of the total fill and ensures that there is enough space for heat dissipation and future modifications, without exceeding the prescribed limits.

Understanding this concept is crucial for electricians and those involved in electrical installations, as it directly affects the compliance with safety regulations and overall performance of the electrical system.