The 18th Edition is coming…

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Written by Mark Lloyd, Product Manager- Power Supplies and Surge Protection



Just in case you were not aware, the British Standard BS7671 more commonly known as the Wiring Regulations are set to change. The 18th edition (BS7671:2018) was published on the 1st of July this year and can be implemented now, and any installations designed post 1st January 2019 will need to comply with the 18th Edition.

There are a number of areas where the regulations have been updated, (mainly to bring the standard in line with various CENELEC standards relating to electrical installations), but I want to focus on the updates relating to protection against transient over-voltages.

One of the key changes to the regulations is an overhaul of the existing protection against over-voltages…clause 443.

In the 17th Edition the subject of over-voltages derived from atmospheric (Lightning strikes) or switching origins was not clearly defined and relied on something called the AQ criteria (conditions of external influence for lightning) to determine if protection against transient over-voltages is needed.  Without going into detail the risk assessment nearly always resulted in no surge protection being included for installations in a large part of the UK.

Now the 18th Edition states that protection against transient over-voltages has to be provided where the consequence caused by overvoltage results in

  • in serious injury to, or loss of, human life
  • Interruption of public services or damage to cultural heritage
  • Interruption to commercial or industrial activity
  • Affects a large number of individuals.

In all other cases, a risk assessment is required except for single use dwellings where the value of the installation or the installed equipment does not justify being protected, and also cases where there has already been a choice made to install surge protection.

In my opinion, the upshot of this is that electrical designers may well include surge protection into designs from the start, or retrofit into an existing building or installation rather than carry out a risk assessment.

If this becomes true, only time will tell…..

If you are interested in surge protection, maybe like me you need to get out more, or you can click on the following link that will take you to a landing page devoted to surge protection for power supply systems. Here you will find links to products, information on the technology involved as well as videos, brochures and some learning modules.

Should you need to discuss your application in detail please do not hesitate to contact me by dropping an email at

Mark Lloyd – Product Manager – Surge Protection & Power Supplies



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