ITU-T Recommendations

Recommendation ITU-T K.98 provides information which can help protect telecommunication equipment installed in the customer premises against damage due to the lightning strikes to the power and telecommunication lines/cables. It shows that, it is possible to protect equipment against a direct strike to power or telecommunication lines provided that the strike point is at a distance of more than a couple hundred metres from the customer premises in an urban area. The information provided takes into consideration the impact of different types of power distribution systems. It determines the impact of both the length of the telecommunication surge protection device (SPD) bonding conductor and the resistance to earth at the customer premises. The necessary isolation level for the protection of equipment without the use of primary protection is also calculated. It recommends the installation of a multiservice surge protective device (MSPD) or equivalent protection as the first level of protection. When necessary, primary protection is required to protect the MSPD or equivalent protection devices. For strikes to the services closer to the customer premises, an engineering solution is required.