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Wiring Regulations Update - What's Happening and When

Amendment-2 to BS7671 18th Edition wiring regulations

The BS7671 18th edition Wiring Regulations became mandatory in January 2019, the Wiring Regulations are constantly updated and the current edition has already seen a set of amendments (Amendment- 1) issued in February 2020 and now a second set of amendments (Amendment-2) issued in March 2022.

When will BS7671 18th Edition Amendment 2 become mandatory?

Amendment 2:2022 to BS7671:2018 Requirements for Electrical Installations was issued on 28th March 2022. You can implement the changes from this amendment now, but the existing version remains valid until 27th September 2022 and you can apply either of the versions until this date. The most important thing to realise is that after September 27th 2022 all installations must comply, even if you designed it before that date.

Which sections from the standard are updated? 411.3.3 - Risk assessment of sockets 531 - Changes in requirements for RCDs 421.1.7 - Requirements for AFDDs 422 - Precautions where particular risks of fire exist 433 - Protection against transient over voltage

411.3.3 Risk assessment of sockets

All socket outlets in dwellings up to 32 A must have RCD protection. In other applications you can only omit RCD protection if a socket is only going to be used by a skilled person while you must also provide a fully documented risk assessment detailing why it is being omitted.

Clearly the intention of this amendment is to improve building safety & to protect against electrocution as a result of an electrical fault. It also shifts the requirement for the RCD protection of socket outlets to who the anticipated user is rather than the location.

531 Requirements for RCD's

In most of the applications using Type AC RCDs will now be absolute. You can still use them on certain circuits for example: simple filament lighting, an electric shower and an immersion heater.

Whereas Type A RCDs provide protection against residual sinusoidal currents and residual pulsating DC currents which means that they can protect all the circuits listed above and also circuits which supply equipment containing active electronic components.

There are a number of different types of RCD based on which you need to choose for specific applications, such as;

Equipment which uses high power electronics and frequency inverters such as washer/dryers & dishwashers. For this equipment the IET recommends using Type F RCDs.

If you are installing EV chargers, depending on the type of charger selected, you may need to use either a type A, B or a type F RCD. And for PV system installations, depending on the inverter which is selected, you may need to use Type B RCD.

421.1.7 Requirements for AFDD's

Despite the safety benefits most installations were not using AFDD’s but Amendment-2 has made this a requirement in high-risk premises to protect final circuits supplying socket outlets with a rated current under 32 A for premises such as:

· High risk residential buildings

· Houses in multiple occupation

· Purpose built student occupation

· Care homes

422 Precautions where particular risks of fire exist

There have been changes to particular risks from fire which are covered in Amendement-2 and the proposed changes are:

· Electrical system designer/installer to provide details of the electrical system explaining associated services including testing and maintenance requirements.

· Specific requirements for “Protected escape routes”.

· Cables or other electrical equipment shall not be installed in a protected escape route unless they are part of an essential fire safety or related safety system e.g. lighting, emergency lighting, or alarm systems.

· Specific requirements for cables in protected escape routes.

· Cables in escape routes shall be as short as practicable.

Cables encroaching on escape routes shall not be installed within arm’s reach unless they are provided with protection against mechanical damage likely to occur during an evacuation.

433 Protection against transient over voltage

Amendment- 2 has updated the wording for overvoltage assessment and equipment. This is important because it changes the approach to the overvoltage assessment.

Primary areas now considered for the use of SPDs, where overvoltage could result in:

· Serious injury to, or loss of, human life.

· Failure of a safety device

· Significant financial or data loss

For all other cases, protection against transient overvoltages shall be provided, unless the owner of the installation declares it is not required due to any loss or damage being tolerable and they accept the risk of damage to equipment and any consequential loss.

Protection against overvoltages shall be considered in the case of equipment likely to produce switching overvoltages or disturbances exceeding the applicable rated impulse voltage of equipment according to Table 443.2, e.g. where an LV generator supplies the installation or where inductive or capacitive loads (e.g. motors, transformers, capacitor banks), storage units or high current loads are installed.


Amendment 2 is a reinforcement of safety measures such as the risk assessment of sockets and the requirement for RCD use, while some others focus on the fire safety. Some of this technological change relates to the equipment which have major electronic components so the devices protecting those circuits must comply to meet the needs.

In other cases, installations shall further improve on the fire safety by providing the devices such as AFDDs that plays an important role against arc faults, which are a major cause of fires.


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