IET Wiring regulations

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IET Wiring regulations

Published: 16 February 2021 · Category: Practical guides

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IET Wiring regulations BS 7671 18th edition Transient overvoltage protection 4 I E T W I R I N G R E G U L AT I O N S B S 7 6 7 1 1 8 T H E D I T I O N The IET Wiring Regulations require all new electrical system designs and installations, as well as alterations and additions to existing installations, to be assessed against transient overvoltage risk and, where necessary, protected using appropriate surge protection measures (in the form of Surge Protection Devices SPDs). T R A N S I E N T O V E R V O LTA G E P R OT E C T I O N - I N T R O D U C T I O N 3 Transient overvoltage protection Introduction Based on the IEC 60364 series, the 18th Edition of BS 7671 Wiring regulations covers the electrical installation of buildings including the use of surge protection. The 18th Edition of BS 7671 applies to the design, erection and verification of electrical installations, and also to additions and alterations to existing installations. Existing installations that have been installed in accordance with earlier editions of BS 7671 may not comply with the 18th edition in every respect. This does not necessarily mean that they are unsafe for continued use or require upgrading. A key update in the 18th Edition relates to Sections 443 and 534, which concern protection of electrical and electronic systems against transient overvoltages, either as a result of atmospheric origin (lightning) or electrical switching events. Essentially, the 18th Edition requires all new electrical system...