Cable holders on exposed roof cable runs must be spaced at intervals not exceeding what distance?

The requirement for spacing cable holders on exposed roof cable runs is guided by safety standards that ensure the proper support and management of lightning protection conductors. The correct spacing interval is established to minimize movement and physical stress on the cables, which can arise from wind or thermal expansion and contraction.

When holders are spaced correctly, it prevents sagging or damage to the conductors, ensuring continuous performance and reliability of the lightning protection system. If cable holders are too far apart, the system could become compromised due to inadequate support, potentially leading to a failure in the protection provided.

The specific interval of 3 feet reflects a balance between practical considerations of cable management and the need for robust protection. This standard helps in maintaining the integrity of the lightning protection system while also adhering to regulatory compliance and industry best practices.

The other distances provided may not adequately support the cables and might expose the system to risks associated with environmental factors, which is why the choice of 3 feet is deemed appropriate and is aligned with established guidelines.