Surge Protection: Let’s make it simple

Surge Protection is required to be installed under both BS7671:2018 and the new I.S 10101:2020, so let's look at why we need it, when it is required and the differences between the standards...

As technology advances, consumers demand that the electrical items we use, get smaller, which means the components inside are also smaller. The reduction in the size of these components over the years now makes electronic equipment extremely sensitive to over-voltages.

An over-voltage – or a surge as they are generally called – are short spikes in voltage, which unknown to most people are occurring all the time. The components inside the electrical equipment we use, are slowly degraded by these surges, which will shorten the lifespan of the equipment. This phenomenon affects everything that is plugged in to power, from your household electronics through to industrial machinery and computers.

Regulation 443.4 gives guidelines around the type of installations where surge protection is now required:

• Result in serious injury to, or loss of, human life
• Result in interruption of public services and/ or damage cultural heritage
• Result in interruption of commercial or industrial activity
• Affect a large number of co-located individuals

I.S. 10101:2020
Regulation 443.4 gives the same guidelines as BS7671:2018 but goes further by giving examples:

a) Human Life, e.g. safety services, medical care facilities
b) Public services and cultural heritage, e.g. loss of public services, IT centres, museums; commercial or industrial activity, e.g. hotels, banks, industries, commercial markets, farms; a large number of individuals, e.g. large buildings, offices, schools

The risk assessment
In both standards, where the installation does not fall under the requirements listed in 443.4, a risk assessment shall be performed. If the risk assessment is not performed, the electrical installation shall be provided with surge protection. The exception to this is domestic installations.

Domestic properties
This is where the two standards slightly differ. BS7671:2018 states that surge protection may be omitted if the value of the installation and the equipment inside the installation does not justify the cost. Ultimately, it is up to the homeowner to decide if they want the SPD installed, but when discussing the requirement of surge protection with the homeowner ensure that they are aware that the value of the electrical installation also includes the replacement cost of all of the fixed wiring and sockets in the property. Also, it is extremely important that if the customer decides not to have surge protection installed, that a signature is obtained to remove liability from the electrician should the customer have an issue with surges in the future.

I.S.10101:2020 states that surge protection may be omitted if the total economic value of the electrical installation is less than five times the economic value of the SPD. Realistically this is more straight forward than the BS7671:2018 regulation as it will be extremely unusual for an electrical installation to be worth less than five times the value of an SPD, meaning that SPD installation under the I.S standard will become necessary in domestic circumstances.

Further CPD
Kirsty Johnson, Technical Director for Surge Devices holds regular webinars on different aspects of surge protection application and installation, including a more in-depth look at the regulations from BS7671:2018 and I.S.10101:2020. Sessions are free and are CPD accredited so every attendee receives a CPD certificate. Book your session at:

T: +44 (0)14 8485 1747
E: [email protected]