scope:

This Recommendation provides the rationale and formulas for calculating the shielding factors used in series K Recommendations dealing with lightning protection of telecommunication lines and structures. The shielding factors considered are related to:

- the use of a metallic tower to hold telecommunication feeder cables and antennas;

- the placement of several feeder cables in a metallic cable ladder in the tower;

- the placement of telecommunication cables in a metallic cable tray;

- the use of a guard-wire above a buried telecommunication cable;

- the connection of a telecommunication cable to earth;

- the use of a telecommunication cable with a metallic sheath.