The most commonly used material for lightning conductors is copper. Copper is an excellent conductor of electricity and is resistant to corrosion, making it ideal for use in outdoor environments. Aluminium is also sometimes used as a lightning conductor, but it is not as good a conductor as copper and is more susceptible to corrosion.

The ideal material for a lightning conductor should have the following properties:

* High electrical conductivity

* Resistance to corrosion

* Strength and durability

* Ability to withstand high temperatures

* Low cost

Copper meets all of these criteria, making it the best choice for lightning conductors.