Recommendation ITU-T K.46 gives a procedure to protect telecommunication lines using metallic symmetric conductors (i.e., twisted pair cables) against overvoltages and overcurrents imposed on the lines due to nearby lightning flashes. The procedure is based on the representation of the line by a sequence of sections and nodes, and the evaluation of each node exposure to the lightning-induced surges. Based on the node exposure, the ground flash density and the earth resistivity, the annual number of surges above a given voltage level is calculated. If the voltage level considered is the impulse withstand voltage of the node, then the number of surges above this level corresponds to the annual number of damages to the node. This number shall be multiplied by the loss due to induced surges in order to obtain the risk of failure due to indirect lightning flashes. The highest risk of all nodes is the risk of the line.
ITU-T K.46-2012 Referenced Document
ITU-T K.12-2010 Characteristics of gas discharge tubes for the protection of telecommunications installations (Study Group 5)
ITU-T K.27-1996 Bonding Configurations and Earthing Inside a Telecommunication Building - Protection Against Interference Study Group 5; 26 pp
ITU-T K.28-2012 Parameters of thyristor-based surge protective devices for the protection of telecommunication installations (Study Group 5)
ITU-T K.47-2012 Protection of telecommunication lines against direct lightning flashes (Study Group 5)
ITU-T K.66-2011 (Pre-Published) Protection of customer premises from overvoltages
ITU-T K.67-2006 Expected surges on telecommunications and signalling networks due to lightning Study Group 5
ITU-T K.72-2011 (Pre-Published) Protection of telecommunication lines using metallic conductors against lightning Risk management
ITU-T K.46-2012 history
2012ITU-T K.46-2012 Protection of telecommunication lines using metallic symmetric conductors against lightning-induced surges (Study Group 5)