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Question 5/5

Question 5/5 – Lightning protection and earthing of telecommunication systems
(Continuation of Questions 5 and 6/5)


In recent years, modern society has experienced a high and steady growing dependency on telecommunications. In this context, the reliability of telecommunication services has become an issue of high priority. Operators all over the world are driving efforts in order to improve the reliability of the entire telecommunication system. In this context, the protection against the dangerous effects produced by lightning flashes and the earthing/bonding procedures of an installation are matters of prime concern. It shall also be reminded that the lack of adequate earthing and bonding may also jeopardize the technical staff and the users of telecommunications services. Furthermore, the evolution of the power architecture of present and future ICT systems leads to the need to study its impact on the bonding and earthing of telecommunication equipment. Therefore, this question aims to establish cost-effective engineering procedures in order to allow the telecommunication operators to achieve the desired reliability in their networks, as well as the safety of the customers.

This Question impacts climate change by ensuring that adequate protective measures for installations reduce the amount of equipment and installation damages. By reducing damages less fossil fuels are burnt (personnel do not have to drive to a site to repair equipment) and less manufacturing is required (less replacement equipment is needed).

The following Recommendations and Handbooks, in force at the time of approval of this Question, fall under its responsibility:

  • K.27, K.29, K.35, K.39, K.40, K.46, K.47, K.56, K.66, K.67, K.71, K.72, K.73
  • Handbook on Earthing and Bonding
  • Handbook on Lightning


The purpose of this Question is to produce new or revised Recommendations and Chapters of Handbooks regarding the protection of telecommunication systems against lightning flashes and the earthing and bonding configurations applied to telecommunications installations (telecommunication buildings, remote electronic sites and customer premises).

Study items to be considered include, but are not limited to:

  • Protection of fixed telecommunications lines, including the lines made of symmetric conductors, coaxial cables and non-metal-free fibre-optic cables, as well as lines used for remote power feeding of telecommunication equipment;
  • Protection of mobile and wireless systems, in particular radio base stations which very often have their antennas installed in high structures exposed to lightning discharges;
  • Protection of telecommunication stations (central office), in particular those that make part of the network’s backbone and, therefore, require a high reliability;
  • Utilization of the data from lightning location systems (LLS) to optimize the network protection;
  • Protection of users of telecommunications services from the dangerous effects of lightning discharges;
  • Bonding configurations and earthing of telecommunication installations, including earthing of power feeding systems in co-located environment;
  • Requirements for earthing and equipotential bonding under transient conditions, as those caused by the fast raising currents associated with subsequent lightning return strokes;
  • Maintenance methods of bonding configurations and earthing.


Tasks include, but are not limited to:

  • Revision of Recommendation K.29 in order to make reference to the relevant parts of Recommendation K.47, highlighting the coordination aspects (Recommendation K.39 could be deleted with the approval of revised Recommendation K.40, as its subject is now covered by IEC 62305-2);
  • Revision of Recommendation K.40 considering IEC62305-3 and IEC62305-4;
  • Revision of Recommendation K.67 based on new information available on the surges due to lightning and including an Annex with probability of currents being exceeded;
  • Maintenance and enhancement of Recommendations K.27, K.35, K.66 and K.73 with better linkage and coordination between these recommendations and other Recommendations within the K-series;
  • New Recommendation on the protection of installations at the neighbourhood of telecommunication towers;
  • New Recommendation on the use of the data from lightning location system (LLS) for network protection;
  • One or more new Recommendations on bonding configurations and earthing of remote sites in co-located environment and in telecommunication centre;
  • New chapter of the Lightning Handbook (Chapter 11) presenting the rationale for the shielding factors contained in the lightning protection Recommendations;
  • Maintenance and enhancement of "Earthing & Bonding Handbook".

An up-to-date status of work under this Question is contained in the SG 5 work programme (use URL as shown in the table below).




  • K-series


  • 2, 4 and 12/5

Study Groups:

  • none

Standardization bodies: