Which strand size is required for a Class II copper main lightning conductor?

The correct choice identifies the required strand size for a Class II copper main lightning conductor as 15 AWG (American Wire Gauge). In the context of lightning protection systems, the wire gauge is critical because it must be able to carry the high currents associated with lightning strikes without sustaining damage or causing failure of the system.

Class II lightning protection systems are designed for environments where lightning strikes can be anticipated, requiring conductors that are sufficiently robust to handle the electrical load. The 15 AWG size strikes a balance between conductivity and mechanical strength, making it suitable for effective lightning current conduction as per established standards.

Selecting an appropriate gauge, like 15 AWG, ensures that the conductor is both effective in redirecting lightning away from structures and durable enough to withstand the thermal and mechanical stresses involved during a lightning event. This choice reflects the standards set by organizations that govern lightning protection systems, ensuring safety and reliability.