A Class I circuit conductor shall have a minimum insulation rating of how many volts?

A Class I circuit conductor is defined by its ability to operate at higher voltages, specifically in environments where the insulation needs to withstand greater stress and potential risk of electrical shock. The minimum insulation rating for Class I circuits must be 600 volts. This voltage rating reflects the need for additional safety measures and better performance in the event of electrical faults or environmental factors.

Such a high insulation rating is crucial for ensuring that the conductors can handle various conditions without compromising safety. Insulation rated for 600 volts provides a robust level of protection against breakdown and ensures the integrity of the fire alarm system, especially in commercial and industrial applications where the risk of exposure to higher voltages is greater.

Using lower voltage ratings, such as those represented in the other choices, would not meet the required safety standards for Class I circuits and could lead to increased hazards, including electrical shock or system failure. Therefore, the requirement for a 600-volt minimum ensures systems are designed with the necessary reliability and safety for their intended applications.