Copper is the best material for conductors. When circumstances are not such as to promote corrosion iron may be used, but of larger dimensions. Its conductivity is about one-fifth that of copper.

Copper lightning conductors should be of the following dimensions:

Rods ½" diameter, tubes 5/8 diameter, 1/8" thick, or bands 1½" wide, 2/3" thick.

Iron lightning conductors should be either solid rods Vf diameter, or bands 2" wide, 3/8" thick.

Lightning conductors afford protection over a circle whose radius equals their height from the ground; formerly considered twice.