Conductors must maintain a horizontal or downward course and avoid which type of pocket?

The requirement for conductors to maintain a horizontal or downward course and to avoid U or V pockets stems from the potential for water accumulation in these shapes. U or V pockets can trap moisture, which can significantly increase the risk of corrosion and other issues related to electrical conductivity and system integrity. When conductors follow a path that leads to U or V pockets, they may not only suffer from deterioration over time but also create potential failures in the lightning protection system.

In contrast, while open pockets and round pockets may also present challenges, they are not specifically characterized by the same level of water retention and the specific risks associated with U or V shapes. Therefore, adhering to the prohibition against U or V pockets helps ensure the long-term reliability and effectiveness of the lightning protection system.