Which of the following conductors is classified as a current-carrying conductor according to 310.15(C)(1)?

The classification of current-carrying conductors according to 310.15(C)(1) focuses on conductors that are actively involved in carrying electrical current during normal operations. The correct choice is the spare or unused conductor in a raceway, which is classified as a current-carrying conductor because it is part of the overall installation, and under certain conditions, it could be activated to carry current. This is key in determining the appropriate ampacity and ensuring that heat dissipation is considered.

In contrast, the other options do not fulfill the criteria for current-carrying conductors in the same way. A control circuit conductor is typically designed for low voltage and does not fall under typical current-carrying classifications associated with higher voltage lines. A neutral conductor that carries only unbalanced current usually does not contribute to the total load sufficiently to be considered a current-carrying conductor per the guidelines set forth. Lastly, an equipment grounding conductor does not carry current during normal operation since its primary function is to provide a path for fault current; hence, it is not classified as a current-carrying conductor.

Understanding the criteria for current-carrying conductors helps in ensuring not only the effectiveness but also the safety of electrical installations, helping to prevent