New to Surge Protection?

Looking for an SPD but not sure what you want? CLICK HERE for our simple, easy to use product selector. Find what you are looking for in seconds.


If you’re new to Surge Protection and find the subject daunting, don’t worry we will help you all the way.

First of all, why do we need Surge Protection . . ?


Lightning, and electrical switching events, can create very short duration but very high voltage ‘spikes’. These are called transient overvoltages (often referred to as surges, but not to be mistaken for longer duration and lower voltage surges that can occur in faulty power supplies).

Lightning up to 1km away causes devastating transient overvoltages
Lightning up to 1km away causes devastating transient overvoltages

Lightning induced surges can exist on all electrically conductive cables eg mains power, data, telephone etc.

These surges can, at worst, destroy sensitive electronic equipment putting lives in danger. At best, they will degrade circuitry and cause damage including data loss.

The cost of transient overvoltage damage, even in domestic settings, can run into many thousands.

CLICK HERE to read more about surges and the damage they can cause.

How to protect . . .

Achieving effective protection against the damaging effects of transient overvoltages is easy with Kingsmill Surge Protection Devices (SPDs).

We have a comprehensive range of SPDs for mains power, charging stations, photovoltaic systems and LED lighting as well as data and telephone lines.

CLICK HERE to see our range of SPDs.

18th Edition (BS 7671:2018)

Previously, the 17th Edition Wiring Regulations stated that the need for surge protection was determined by risk assessment.

Since 1 January 2019, according to BS 7671:2018 section 443.3, protection against transient overvoltages shall be provided where the consequence of damage caused by overvoltages meets certain criteria.

If these criteria are not met, a risk assessment must be carried out to determine if surge protection is required. If a risk assessment is not carried out, surge protection must be installed.

We’ve developed a simple to use 18th Edition SPD selector – CLICK HERE.

Kingsmill 18th Edition Wiring Regulations

BS:EN 62305

Surge Protection that complies with the requirements of BS:EN 62305 is more complex and applies to buildings that have structural lightning protection.

If you’re not familiar with BS:EN 62305, contact us for more information. If you are familiar with the standard, and the concept of Lightning Protection Levels (LVL) and Lightning Protection Zones (LPZ), CLICK HERE to start your product search.