As the ambient temperature increases, how is the ampacity of a conductor affected, according to Table 310.15(B)(1)?

As ambient temperature increases, the ampacity of a conductor decreases due to the physical properties of the conductor materials and how they thermally interact with their environment. Ampacity is defined as the maximum amount of electrical current a conductor or device can carry before sustaining immediate or progressive deterioration.

When the temperature rises, resistive heating occurs in the conductors, leading to a higher overall temperature. The National Electrical Code (NEC) outlines that conductors are rated for specific temperatures, and exceeding these ratings can cause the insulation to degrade and poses a risk of overheating, which can lead to potential fire hazards.

Table 310.15(B)(1) provides specific ampacity ratings based on different temperature conditions, indicating that higher ambient temperatures lead to a reduction in the allowable current-carrying capacity of a conductor. This is because the conductor may not be able to dissipate heat efficiently, leading to overheating if the ampacity was to remain constant under higher temperatures.

Therefore, the correct understanding is that as ambient temperature increases, the ampacity of a conductor decreases to maintain safety and operational efficiency.