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The New BS 7671: 18th Edition Wiring Regulations

BS 7671:2018 was issued on the 2nd July 2018 and is intended to come into effect on 1st January 2019. Installations designed after 31st December 2018 are to comply with BS 7671:2018. 

In this article Geoff Cronshaw answers some of the typical questions that are raised and look at the impact that some of the changes introduced by the 18th Edition will have on the industry. 







Changes to the requirements concerning surge protection
Clause 443 of the 18th Edition (BS 7671:2018) deals with protection of electrical installations against transient overvoltages (surge protection) of atmospheric origin transmitted by the supply distribution system, and against switching overvoltages generated by the equipment within the installation. Clause 443 contains significant changes.
The AQ criteria (conditions of external influence for lightning) for determining if protection against transient overvoltage is needed is no longer included in BS 7671. Protection against transient overvoltage now has to be provided where the consequence caused by overvoltage affects:
  1. serious injury to, or loss of, human life;
  2. interruption of public services and/or damage to cultural heritage;
  3. interruption of commercial or industrial activity; and
  4. interruption affects a large number of collocated individuals.
For all other cases, a risk assessment would have to be performed in order to determine if protection against transient overvoltage is required. If the risk assessment is not performed, the electrical installation will have to be provided with protection against transient overvoltage.
However, an exception not to provide protection is included for single dwelling units where the total value of the installation and equipment therein, does not justify such protection.
There are different types of SPDs. Type 1 are generally installed at the origin of the installation and type 2 are generally installed at distribution boards within the installation.  It is important that SPDs are selected and installed in accordance with the manufacturer’s instructions.

The full article can be accessed at the below link. 


The 18th Edition (BS 7671:2018) is launched

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