Surge Protection: 18th Edition

The 18th Edition will bring many changes to the industry in January, and Surge Protection is one of the most significant.

Protection against transient overvoltages – more commonly called surges - used to be determined by a system known as the AQ criteria. That was the 17th edition. In the 18th edition, the rules have changed.

Hager Surge Protection

Now, in the new regulations, clause 443 states that protection against transient overvoltage has to be provided where the consequence caused by overvoltage results in:

  • serious injury to, or loss of, human life;
  • interruption of public services and/or damage to cultural heritage;
  • interruption of commercial or industrial action; and
  • interruption affects a large number of co-located individuals.

In all other cases, a risk assessment would have to be performed to determine if protection against transient overvoltage is required.

Why the change?

Electrical equipment has evolved, but items such as televisions, alarms and printers are all vulnerable to transient overvoltage, which can reduce the equipment’s lifespan through degradation and damage. Electronics are also getting smaller, which makes individual components more vulnerable to damage from electrical surges. As a result, the number of applications and the technical requirements for surge protection devices are scaling up.

The other reason is, of course, safety. If surges are going to cause injury or loss of life, it’s a no-brainer that the new rules should call for protection on those projects.

18th Edition

The changes to the new wiring regulations mean that SPDs will be required for many installations in commercial, public, industrial and housing schemes. SPDs must now offer the right level of protection against repeated worst case overvoltages.  There are three types of SPDs on the market, all of which handle different types of surge current:

Type 1: These are designed for installation at a facility’s service entrance and are also known as equipotential bonding SPDs that protect against major surges from a direct lightning strike.

Type 1 protects against loss of life and serious injury. They should be used on a building that has an overhead supply or lightning protection system on the roof.

Type 2: SPD Type 2 can prevent the spread of overvoltages in electrical installations and protects equipment connected to it.  They are required to protect the electrical and electronic systems.

Suitable for all other installations at the incomer or after a type 1 SPD at sub distribution level.

Type 3: These SPDs have a low discharge capacity and are designed to protect sensitive or critical loads, particularly from switching transients.


There are also Combined Type SPDs, which bring multiple Types together in a single unit – this can simplify installation and maintenance, plus save on cost.

Top products

Hager SPD Pluggable photovoltaic 25kA class 2

  • Complies with IEC 61643-1
  • Comes with a lifetime indicator installed.Wylex 3Conductor System NHSPD4421T12

Wylex 5 Conductor System

  • Three phase supply – separate protective Earth and Neutral
  • 4 mod DIN mounting SPD with remote indication contact

Wylex 3 Conductor System

  • A type 1 and 2 lightning/surge arrester combination
  • 4 mod DIN mounting SPD with remote indication contact

Download the Wylex Surge Protection brochure for the full range.

BG Electrical Retrofit Surge and Lightning Protection Enclosure

  • Stand alone enclosure to be fitted to existing consumer units to provide lightning and surge protection.
  • Supplied with 100A mains switch to enable SPD and consumer unit to be isolated.

For more SPDs, please refer to the BEW Electrical Product Catalogue or ask for advice in branch.