Transient Overvoltage Protection
Chapter 44, regulation 443.4.1 & 443.4.2 refers to the protection of electrical installations against transient overvoltage, in part due to the increasing prevalence of indirect lightning strikes but also relating to switching loads causing transients on a network. Protection against transients shall be provided whether consequence caused by the overvoltage could result in serious injury or loss of human life, failure of a safety service, as defined in Part 2, or a significant financial or data loss. For all other cases, protection against transient overvoltage shall be provided unless the owner of the installation declares it is not required due to any loss or damage being tolerable and they accept the risk of damage to equipment and any consequential loss. Surge protection devices (SPD) are designed to immediately drive any overvoltage to earth. Consumer units with pre-populated SPDs are available for new or replacement installations, whilst enclosure only units are ideal for retrofit.