What is “derating” when referring to conductors?

Derating refers specifically to the practice of reducing the current-carrying capacity of conductors in order to prevent overheating and ensure safe operation. This is crucial for maintaining the integrity of electrical systems and components, especially when conductors are grouped together, exposed to higher ambient temperatures, or when they are installed in certain types of raceways. When conductors carry more current than their rated capacity, they can overheat, which can lead to insulation failure and potentially start a fire. By derating, engineers and electricians ensure that conductors operate within safe limits, which helps to extend their lifespan and maintain the safety of the electrical installation. This process is often guided by standards set forth in electrical codes, such as the National Electrical Code (NEC).