SPD Regulations Guide – 18th Edition
SPD Regulations Guide – 18th Edition
Some more big changes to the wiring regulations were introduced recently, specially the SPD regulations in the 18th edition AMD2.
Although there have been requirements for Surge Protection Devices (SPDs) in certain particular instances for a long time, the release of the 18th edition in 2018 really brought them into the forefront.
The original 18th edition SPD regulations were based around the risk of overvoltage from atmospheric origin. As such a flash density map was the main part of the original 18th rules.
This map showed the different areas of higher risk from thunderstorms. This was entered into an equation to show whether or not SPD protection was required.
When they were first introduced, electricians were only fitting them where required due to the cost of the relatively new pieces of kit. As they have become more widespread, and inevitably cheaper, fitting them became a bit of ‘standard practise’ for decent electricians. The cost of modern TVs and other electronics in the home is not worth skimping the £30-£50 cost of fitting an SPD to a new consumer unit.
Whilst we would normally list all the requirements individually, this all changed with the advent of the 18th Edition Amendment 2 in March 2022. The latest version of the wiring regulations has a completely revised set of requirements for SPD protection.
We’ll delve further into these latest 18th edition AMD2 regulations below:
Where Should Surge Protection Be Installed?
22nd March 2022 was the release of Amendment 2 to the 18th edition of BS7671, the wiring regulations.
This brought radical changes to Chapter 44, Protection Against Transient Overvoltages
SPD protection is now required in instances where there is a risk of:
Serious Injury To, Or Loss Of, Human Life
SPDs are required to be fitted where transient overvoltage may cause serious injury to, or loss of, human life.
An example of this (but not limited to) could be in the instance of medical equipment which may be damaged by a surge. As this would directly affect human life, SPD protection must be fitted.
Failure Of A Safety Service
Surge protection is required to be fitted where overvoltage may cause a failure of a safety service. This could be a fire alarm, automated fire sprinklers, or even emergency lighting.
If anything that is considered a safety service, or circuit supplying such a service, and it will be negatively affected by overvoltage, it must now have an SPD fitted.
Responsibility is given to the appropriate British Standard regulations for the following:
- Emergency Lighting systems – Regulation 560.9
- Fire Detection systems – Regulation 560.10
- Life safety & fire fighting – Regulation 560.11
Significant Financial or Data Loss
This one goes deeper than you would think. The SPD regulations make no definition as to what they call ‘significant financial loss’.
It could be reasonably assumed that if the potential damage caused by an overvoltage occurence is MORE than the cost of fitting a surge protection device, then it would be classed as significant.
With the advent of modern TVs bristling with electronics, kitchen appliances with every advancing motors and variable drives, potentially EV chargers and the like, all these cost SIGNIFICANTLY more than the cost of fitting an SPD.
Whilst the cost of SPDs is relatively low, even just one of these items could be 10x the cost fitting an SPD when the appropriate works are being completed.
Significant data loss could easily occur in a modern household where computers and mobile devices are present. If these are plugged in at the time of a serious overvoltage they could easily be damaged, causing data loss.
As an absolute minimum, expect this to apply to mandatory fitting of SPDs in the instance of offices and other areas where there are lots of computers. Again, it would be wise to approach this with a ‘best practise’ attitude and just fit the SPD for the low cost of them.
Other Situations
Regulation 443.4.1 then goes further to state that for all other cases, SPD protection shall be provided unless the owner of the installation:
- Declares They Do Not Want Them Fitting as the potential loss is deemed to be tolerable.
- Accepts The Risk Of Damage to Equipment & any consequential loss.
In these instances you should be getting the customer to sign a waiver stating that they are happy for SPD protection to be omitted.
As stated higher up in this guide, the cost of fitting SPD protection is now below the cost of much of the electrical equipment in a standard home. Ever more sensitive electrical equipment has meant that SPD regulations have had to catch up!
Do You Need Surge Protection In A Domestic Property?
Whilst the original 18th edition regulations gave a little room for interpretation across domestic properties, the latest amendment 2 (AMD2) contains a couple of different stipulations.
As we discussed above, ‘significant financial loss’ is difficult to define, and a £500 TV is not uncommon these days. As the cost of an Surge Protection Device (SPD) is somewhere in the region of £50 (cheaper ones exist, as do more expensive), the loss of an appliance which costs 10x that of the SPD could be argued to be significant.
T2 SPDs fitted in the consumer unit will protect against more than just a single huge overvoltage incident, as in that you would experience from a lightning strike. They protect against a barrage of smaller ebbs and flows in the incoming voltage such as those caused by switching.
This means that they can help to extend the lifetime of that fancy TV. That is definitely something to think about when considering a surge protection device for home
Another factor is the introduction of needing a waiver signing to say the customer doesn’t want it fitting. Ultimately this just adds up to the simple fact that SPDs need to considered as standard fit equipment when upgrading consumer units in 2022 and beyond.
Summary of SPD Regulations 2024 + More Info
As the requirements placed on electricians from the latest SPD regulations gets more in depth, it is important to keep up with the latest news and information surrounding these changes.
This is even more important since the CPS (Competent Scheme Providers) now require electricians to complete an element of CPD (Continous Professional Development) as part of being registered.
Here is a small selection of links to further information regarding the SPD regulations (and the 18th AMD2 as a whole) which we found to be useful, and can be recorded as CPD time:
Surge Protection Device Wiring Diagram
As a quick extra, check out the wiring diagrams for connection both single phase & three phase surge protection devices:
