Lightning strikes are sometimes cited as part of the cause of data center failures, including recent incidents at Google’s Ghislain data center in Belgium, and the Singapore Stock Exchange. However, protecting data centers from lightning strikes is no easy task. There are regularly updated documents for guidance, but nothing beats the expertise of an experienced professional to design and specify a protection system to ensure the safety of the building and everything in it, including personnel. Continuity of power in a data center is paramount. Data centers consume huge amounts of energy, not just to run the IT systems, but also to cool equipment. The data centers of large companies have now increased to an average of 32MW, which is roughly the equivalent to a town of 25,000 inhabitants. In general, data centers are required to have high systems availability with a maximum of four minutes downtime per year, which can only be achieved with redundancy of power supply from the energy distributor. To reduce the risk of power failure they usually have two medium-voltage sources, one of which serves as a backup. A third source, in the form of generators, is often found on site along w...