When routing several cables through the same hole, at what length must derating factors be applied?

Derating factors are applied to ensure that the cables maintain safe operating temperatures when multiple cables are grouped together. This is due to the increased heat generated from the combined electrical load, which can lead to overheating if not properly managed. The specific length at which derating must start to apply is typically based on industry standards and guidelines.

In this case, the correct length is 24 inches. When cables are routed together in proximity, typically after a straight run of 24 inches, the buildup of heat requires consideration for derating to prevent potential overheating. This standard helps maintain safety and ensures the reliability of the cable installations.

Applying derating factors below this specified length may not adequately account for the cumulative heat generation that arises from the close grouping of cables. Thus, practicing caution and adhering to the 24-inch guideline is essential when planning cable installations for various applications, ensuring compliance with electrical safety and performance standards.