Surge Protection Devices (SPD) and the 17th Edition 1st Amendment of BS7671 Wiring Regulations
Surge Protection devices available from DEM Manufacturing (branded Roxburgh EMC) have for many years offered market leading protection from damage caused by high energy short duration electrical transients. These are typically caused by nearby electrical storms (atmospheric origins) or the switching of inductive, capacitive and resistive loads (switching origin). Transients can cause a variety of problems from equipment failure to serious electrical fires and damage to distribution systems.
BS7671 17th Edition, Chapter 44 relates to protection against Voltage Disturbances and Electromagnetic Disturbances. Section 443 deals specifically with protection against over-voltages of atmospheric origin or due to switching. Details are given as to the types of installations where the risk assessment will always lead to the result that SPD is required and other areas with lower levels of consequences where calculations can be used to determine the need for SPD installation. See specifically 443.2.4.
Chapter 53 deals with protection isolation, switching, control and monitoring with 534.2 determining specifically the selection and erection of surge protection devices. Two specific types of SPD are referred to in the regulations as Type 2 and Type 1 dependant on the nominal discharge currents expected and the location of the protection within the system. DEM´s Surge Protection Devices meet BS EN 61643-11 and DEM´s class B (DVSB series) meet Type 1 and DEM class C (DVSC series) Surge Protection Devices meet Type 2 specifications as referred to in chapter 53.