When making a mechanical connection for a lightning conductor, the steel must be cleaned down to what?

When making a mechanical connection for a lightning conductor, it is imperative that the steel is cleaned down to the base metal. This is crucial because a clean, uncoated metal surface ensures the best possible electrical conductivity. The effectiveness of a lightning protection system relies heavily on low-resistance paths for any lightning currents to safely ground without interruption or resistance, which can occur if connections are made to painted, galvanized, or oxidized surfaces.

Painted surfaces can create a barrier that impedes electrical flow, while galvanized layers and oxide layers do not provide the necessary conductivity. Thus, achieving a connection with clean base metal allows for optimal performance in grounding and effectively protecting structures from lightning strikes.