The Handbook “The protection of telecommunication lines and equipment against lightning discharges” was originally published in 1974, followed by the publication of additional Chapters 6, 7 and 8 in 1978. The ITU-T Study Group 5 has now prepared further new Chapters 9 and 10: Chapter 9 on fibre optic cable lightning damage assessment and Chapter 10 on overvoltages and overcurrents measured on telecommunication subscriber lines.