Surge Protective Devices. Components. Low Voltage Systems

Electrical equipment used in both domestic and industrial applications is increasingly sensitive to surges, due to the massive use of electronic components. Incandescent light bulbs and washing machine motors, for example, have a fairly high intrinsic resistance to surges. So, for a long time, their protection against surges was not a major problem.

These days, LED lights, alarms, computers, televisions and even washing-machine programmers use electronic components, making them more vulnerable to power surges. The growing use of protected sockets (sockets with built-in surge arresters), which can be found in DIY stores and mail-order catalogs alike, is a clear sign of the rapid evolution of surge protection and its penetration into the domestic environment.

However, surge arresters are more than just protected outlets, which generally only act as a secondary barrier against surges. Surge arresters must first be installed in the installation's input panel, to divert dangerous surges to earth as quickly as possible and ensure equipotential bonding. Surge arresters installed downstream of this first arrester (in switchboards or in sockets) only serve to stabilize the potential at sensitive points on the network, and to divert to ground the small part of the overvoltage that has not been fully eliminated by the upstream surge arrester. For more information on lightning arresters and how to install them, see [D4841] . It's vital to choose the right surge arrester(s), and to install them properly.

However, surges can propagate to the device in question, not only via power lines, but also via telephone lines (fax machines, answering machines, boxes...), coaxial cables (terrestrial or satellite TV antennas...), data circuits (USB or HDMI sockets on computers) or even via the earth circuit (in the case of a building protected by a Lightning Protection System, for example). Information on low-voltage networks useful for surge arrester selection is presented in this article.

Ideally, every surge pathway in a structure should be protected, and so there are many different types of surge protectors on the market, in addition to those for power lines. A description of these different types of arresters can be found in the article