A lightning protection system provides a low-impedance route or routes for the electric current to the ground. To lower the series inductance of the down conductor, you can split current to several parallel conductors, preferably located at opposite sides of the protected structure (for example a radar tower), or distribute it evenly around it, in case of more than two down conductors. Spacing affects the inductance: 1 m (3 ft) spacing of two parallel conductors reduces the net inductance to 60 % of a single similar conductor.
A mast is a special case where only one down conductor is used.
Adding extra conductors decreases the current in one conductor, causing less mechanical and thermal stress and reducing the risk of sparking and side flashes.
Several paths also make redundancy in the system in case one joint or connection becomes loose or corroded.