Within how many inches of the lightning protection system conductor contact point to the earth should aluminum not be used?

Aluminum should not be used within 18 inches of the lightning protection system conductor contact point to the earth due to its conductivity and how it interacts with other materials when exposed to moisture and electrical energy. When aluminum is placed in close proximity to a lightning protection system conductor, it can create a risk of galvanic corrosion when in contact with dissimilar metals, particularly in the presence of moisture. This corrosion can lead to a degradation of the system's integrity, ultimately compromising its effectiveness in providing protection against lightning strikes.

Maintaining a minimum distance from the conductor contact point is crucial to ensure safety and functionality, as it helps prevent these potential issues. In scenarios where aluminum is used too close to this critical point, there may be an increased risk of electrical failures or other complications that could reduce the lightning protection capabilities designed into the system.