Down conductors should be made of which thickness of structural steel at a minimum?

The minimum thickness of structural steel for down conductors is specified to be 3/16". This thickness is essential to ensure sufficient mechanical strength and conductivity. Down conductors need to handle the substantial electrical current generated during a lightning strike while also being robust enough to withstand environmental factors like wind and ice loading.

Using steel that is too thin could result in structural failure or inadequate conductivity, while a thickness above the minimum may not be cost-effective and could unnecessarily increase the weight and complexity of the installation. Therefore, 3/16" strikes a balance by providing the necessary protection and conductivity while adhering to industry standards for safety and performance.