The protection concept for IT equipment must be able to handle both partial lightning currents and surge voltages, and requires customization appropriate to the data transmission system used.

The first measure in constructing effective surge protection is to determine where the system surge voltages or lightning effects are likely to occur. Inter-building cables in particular are at risk of lightning strikes. Should bodies of water be located near the building, a higher rate of lightning strikes may be expected, as well as a greater risk potential. IT devices connected to inter-building cables are therefore in particular danger.

When lightning strikes, damage occur both directly at the point of impact, and may also induce surges to equipment within a radius of several hundred metres. The damage occurs through magnetic coupling within the inevitable conducting loops which are inherent to virtually all electrical systems. Such loops cannot be avoided completely, so it is necessary to install surge voltage protection devices at both ends of the inter-building cabling for data transfer and power supply. In order to protect against surge voltages in the central computers, all data lines coming from other buildings must be equipped with surge voltage protection.

With the protection loop all closed, power surges coming from external sources are safety discharges into the ground by means of the potential equalization system and thus kept away from the end devices.