When aluminum is used as a downlead cable, how far must it be terminated above grade?

When aluminum is used as a downlead cable, it must be terminated at a height of 18 inches above grade. This requirement is established to ensure the safety and effectiveness of the lightning protection system. The specified height helps to minimize the risk of accidental contact with the downlead cable and ensures that it functions correctly by providing an efficient path for lightning current to reach the ground.

Termination above this specified height helps to reduce the possibility of physical damage to the cable as well as accessibility issues that could lead to interference with vegetation, construction, or other fixtures. Furthermore, adhering to this standard enhances the overall integrity of the lightning protection system, ensuring it is grounded correctly while also complying with established codes and standards necessary for effective lightning protection.