Bonding of metallic conduit to the lightning down conductor needs to be done at how many ends?

The correct answer indicates that bonding of metallic conduit to the lightning down conductor needs to be done at only one end. This practice ensures that the conduit is effectively integrated into the lightning protection system without creating multiple grounding points that could result in unequal potentials.

When bonding at just one end, the metallic conduit can efficiently conduct any lightning strikes to the ground, minimizing the risk of side flashes or damage to the conduit itself. By avoiding multiple bonding points, the system maintains a common ground potential, which is critical for safety and optimal performance of the lightning protection system.

Establishing too many bonding points can lead to complications, as potential differences could arise across different points, possibly leading to unsafe conditions or equipment damage. Thus, bonding at a single point is a standardized practice in lightning protection design.