ISDN and DSL installations allow fast transfer of large amounts of data. The drawback is that surges can also rapidly reach the terminal device and damage computer equipment. The danger can be overcome by balanced use of basic and precision protection devices.

A system widely used for in-house networks is coaxial Ethernet. There are two variants of this bus system: Ethernet 10Base2 uses BNC connectors, Ethernet 10Base5 uses N connectors. For precision protection, all computer outputs (e.g. server, network cards, etc.) should be fitted with surge protectors. This provides the computer installation with perfect surge protecion.

Connection to the Internet via 56k modems means that analog telecommunication installations are also more prone to damage due to partial lightning current. Devices that are particularly suitable for the protection of analog telecommunications equipment are surge protectors RJ11-Tele/4... and RJ45-Tele/4....

Ethernet Twisted Pair has become the established system for computer networks in buildings. In this system, which is used mainly for in-house solutions, UTP5 RJ45 connectors are generally used. Precision surge protectors installed directly at the terminal equipment protect against capacitively and inductively coupled-in surges.