Case study # 2.7 Title Lightning damage to a telephone Type of trouble Damage. Source of trouble Lightning. System affected Customer equipment. Location Customer premises. Keywords Damage, lightning surge, inherent resistibility, GDT Version date 2004-01-01 System configuration The problem equipment is a telephone powered from the telecommunication line, in a customer premises. An integrated circuit (IC) in the phone was being physically damaged (impulse type damage). It was assumed that lightning was causing this damage and loss of function. Of the 50 customer premises investigated, half had primary protection and the other half did not. Most customers remembered a very close lightning strike. Electricity supply box Terminal block with SPD when required Bonding conductor Main earth conductor Miti(08)_F2.7-1 Electricity supply earth electrode Underground telecommunication cable Figure 2.7-1 – System configuration Copyright © ITU 2010 – All Rights Reserved