How many down conductors are required for lightning protection systems on any type of structure?

The requirement for having at least two down conductors in lightning protection systems is based on ensuring reliability and safety. Having a minimum of two conductors allows for enhanced current distribution and provides redundancy. In the event that one down conductor is compromised or fails, the second conductor remains functional, thereby maintaining the integrity of the lightning protection system.

Additionally, using two down conductors can help minimize the potential for side flashes by reducing the voltage difference at the potential rise points. This is particularly important in larger structures, where the lightning current can be quite substantial.

Implementing multiple down conductors also helps to comply with certain standards and guidelines regarding lightning protection, as they provide a more effective means of grounding for the system. By ensuring that there are at least two pathways for lightning currents to follow safely to the ground, the overall safety and efficiency of the lightning protection system are significantly improved.