top of page

AMENDMENT 2 to BS 7671:2018 (18th Edition of the IET Wiring Regulations)

AMD2 Introduces significant changes to BS 7671:2018
(18th Edition of the IET Wiring Regulations) 

Amendment 2 came into effect on the 28th of March 2022. This essential update to the IET Wiring Regulations will form the national standard to which all new electrical installations and additions, and alterations to existing electrical installations in the UK are to comply.


The new regulations will be fully implemented on 28th September 2022 when the current regulations are withdrawn.


Luceco Group has a range of resources and events to support contractors with the changes, as well as a range of products that comply including:

•  Webinars
•  CPD events

•  Articles & Resources

•  Ask the Expert FAQ

The IET and BSI are now urging all electrical professionals to ensure they become familiar with the changes.

Amendment 2 changes include:

  • Surge Protection Devices will become more commonplace in most installations, especially in residential applications;

  • A new requirement for Arc Fault Detection Devices (AFDDs) in some AC final circuits for installations in some types of higher risk residential buildings;

  • A Type RCD's/RCBO's devices will be used in place of A Type devices, leading to an increase in demand for RCBO devices in residential applications


Surge Protection

The importance of surge protection


Arc Fault Detection Devices

What do they do and why do we need them?


A Type RCDs

What do they do and why do we need them?


Guidance on Language

Understanding the definitions featured in BS 7671

Further Amendment 2 Changes

Understanding the key points from Amendment 2


Amendment 2 - Overview & Changes

Changes to BS 7671: 2018 and the introduction of Amendment 2


Colin McAhren discusses Arc Fault Detection Devices (AFDDs)

Surge Protection

Colin McAhren delivers a webinar on Surge Protection

A Type Devices

Colin McAhren outlines Residual Current Devices (RCDs) and how they protect electrical installations


bg logo.png


BG is running a series of AMD2 training and awareness events throughout the UK in 2022 ...

Please contact your local Area Sales Manager for details of your nearest event



Colin McAhren MIET

Luceco's Technical Expert

You can use the 'Ask the Expertcontact form below to submit any questions you might have around the 18th Edition - 2 Amendment changes.

We will post the questions and answers in the FAQ section below.

Thanks for your Submission!

Colin McAhren

Colin McAhren

Technical Business Development Manager



  • What is the 18th Edition BS 761?
    The IET Wiring Regulations is currently in its 18th Edition. BS 7671:2018+A2:2022 was published in March 2022 and came into effect on 28 March 2022.
  • I have mains powered smoke alarms throughout my house and have an 18th edition consumer unit including individual RCBO's. My question is, as there is no addition ways to add a SPD, I have purchased a mains double pole mains isolator with a type 2 SPD included, will this suffice to cover AMD2 requirements for SPD on safety circuits as long as requirements for length of live/earth cable is met?
    Yes, SPDs monitor the supply cables for high transient voltages in parallel. The use of independent enclosure with SPD and associated protection device for SPD where required will meet the requirements.
  • What is Amendment 2 to BS7671:2018?
    Amendment 2 of the 18th edition wiring regulations released on 28th March 2022, changes installation practices for contractors and the products they use for certain applications, particularly for the installation of domestic consumer units.
  • When does Amendment 2 come in to effect?
    Amendment 2 comes into effect immediately, and the previous version, BS 7671:2018+A1:2020, will be withdrawn on 27th September 2022.
  • Does the CPD form part of a City and Guilds Exam?
    No, this is not an exam it is professional accredited learning
  • What does ECS stand for?
    ECS stands for Electrotechnical Certification Scheme
  • Does your CPD carry points?
  • If I haven’t sat the 18th Edition Exam, can I come along as I have an ECS card still in date?
  • If I haven’t sat the 18th Edition Exam, can I come along?
  • Will the certificate be sent or can we pick it up?
    Your certificate will be issued via email
  • What does CPD stand for?
    CPD is short for Continued Professional Development
  • Will this CPD go towards my ECS CPD points?
  • Should I have received a confirmation email after registering my interest?
    No, we will be amending the system and customers will receive a confirmation email by next week.
  • Will this CPD go towards my ECS learning accreditation?
  • Do we get a certificate?
    Yes - a certificate will be issued with a CPD reference code


AMD2 CPD - WIX Banner 980 px.jpg


IET Logo

Updates to the IET Regulations


Introduction to AFDDs

Understanding the definitions featured in BS 7671


To help all users of BS 7671, the new Amendment 2 regulations now include a section on guidance on the language used. 

There was a need to clarify how words should be interpreted when used within a regulation.  The following definitions apply specifically to the language used within this standard. Shall (requirement) is one word to look for to see if something must be done.  





Possibility and capability



Verbal Form







The content of this table is based on: Rules for the structure and drafting of UK standards published by BSI Standards Ltd.



What are the changes?

443.4 has been re-written and now states the following: 
443.4.1 - Protection against transient overvoltages shall be provided where the consequence caused by the overvoltage could result in:
(I)   Serious injury to, or loss of human life
(II)   Failure of a safety service, as defined in part 2
(III)   Significant financial or data loss

Indent (II) must be carried out regardless of any later considerations. The definition of a safety service in part 2 is:

An electrical system for electrical equipment provided to protect or warn persons in the event of a hazard, or essential to their evacuation from a location, including smoke alarms, heat alarms and fire alarm systems.

Where smoke, heat, or fire alarm circuits are connected to the mains supply, it is mandatory to protect against high transients with a Type 2 Surge Protection Device.

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.

However, if a discussion takes place, the contractor must provide details of the effects of high transient voltages to the owner. And if the owner of the installation still says no, the contractor now must add this to the installation documentation as a departure, from the requirements of BS7671.

For all other cases, installers shall provide Surge Protection or have a detailed chat explaining the reasons why a Surge Protection Device needs to be fitted, based on how transient voltages will over time damage electronic devices.

The fundamental principle here is that protection against voltage disturbances and measures against electromagnetic disturbances must be provided.

131.6.2 - Provides guidance around overvoltages, particularly those of atmospheric origin.

Persons and livestock shall be protected against injury, and property shall be protected against damage, as a consequence of overvoltages such as those originating from atmospheric events or from switching, in accordance with section 443.

For domestic installations, this means that transient Surge Protection must be fitted as standard within consumer units. 


Why Surge Protection is important and the considerations around it? 

Fixed wiring installed within UK residential properties includes more embedded electronic circuits with the likes of: USB charger sockets, LED lighting, heating controllers and the most important connected load in the property; smoke and heat alarms. All these items will be disadvantaged by high transient voltages.

It is becoming increasingly important to protect alarm systems from potential damage. Surge Protection Devices should be considered every time smoke and heat alarms are added to an electric wiring system. High voltage surges have the potential to cause damage to the electronic circuit within these safety devices. Regardless of personal preference, every precaution should be taken to protect the alarm circuits. In doing this, it is not only protecting individuals but the property too.

As technology continues to change the world, modern appliances such as washing machines, dishwashers, tumble dryers, fridges, TVs have entered a new age of digital transformation and are used by the majority. At Luceco Group, we recommend the use of Surge Protection Devices to protect against a damaging transient voltage, or series of transient voltages that have the ability to cause damage to installed appliances over time.


The majority of consumers purchase home contents and electrical appliance insurance cover. The extra cost of a Surge Protection Device could equate to the cost of two months insurance cover, whilst at the same time insuring against the transient voltages that are generated by lightning - this is not generally covered by home or appliance insurance policies. 

Older electrical appliances will include fewer electronic devices, be less smart, less expensive, and will not have an array of LED illumination, not to mention the Wi-Fi and Bluetooth connectivity that is often included. Electronic technology provides the home with much more functionality and control, but it also enables previously insignificant transient voltages to cause damage to many of these devices.

Type 2 Surge Protection Devices

It is important to consider: 

Value of life:

What value do we put on the smoke/heat alarm being damaged by a transient voltage?


Value of property:

Will the homeowners' contents/appliance insurance payout for transient voltage damage?

To ensure consumers are fully aware of what they are protecting against in the home with Surge Protection, the answer is transient voltages, not lighting strokes that have the ability to damage residential properties. Unless lightning protection earthing grids, lightning rods and earth ground stakes are installed, along with Type 1 Surge Protection Devices on all possible routes into the building.


A Type 2 Surge Protection Device will not protect against a lightning strike. They are designed to protect against transient voltages of up to 6000 Volts.

It is vital to understand the fixed wiring connected accessories and connected appliances. Certain electrical assemblies, appliances and accessories will as part of their design and test process, be subject to-rated impulse voltage tests. These tests are performed to demonstrate that if a high voltage/transient is experienced, this voltage will not cross air gaps between conductors and earth parts of the circuits and appliance. These transients are not selective, they will try to find a path of least resistance. 

As insulation and distances between electronic circuits are reduced due to previous high transients, following transients increase the opportunity to produce a catastrophic failure event.

Upon consideration of two important factors, the value of life and the value of the property, consumers should have the opportunity to make informed decisions regarding the installation of Surge Protection Devices, with a clear understanding of how important they can be. 

For more information on BG's extensive range of Surge Protection devices, please click here!


BS 7671 - Chapter 42 - Protection Against Thermal Effects

What are the changes?

Locations where AFDDs are mandatory

421.1.7 Arc fault detection devices (AFDD) conforming to BS EN 62606 shall be provided for single-phase AC final circuits supplying socket-outlets with a rated current not exceeding 32A in:

  • Higher Risk Residential Buildings (HRRB)

  • Houses in Multiple Occupation (HMO)

  • Purpose-built student accommodation

  • Care homes

Note 1: HRRBs are assumed to be residential buildings over 18m in height or in excess of six storeys, whichever is met first. 
It is anticipated that in many areas, higher-risk residential buildings will be defined in legislation which can be subject to change over time, as well as in risk management procedures adopted by fire and rescue services. Current legislation should be applied.   

Regulation 532.6 provides installation information. Where specified, AFDDs shall be installed:

  1. at the origin of the final circuits to be protected, and

  2. in AC single-phase circuits not exceeding 230V


When using busbar systems to BS EN 61439-6, and power track systems to BS EN61534, AFDDs may be placed at a location other than the origin of the circuit, so they could be installed into each socket.

Locations where AFDDs are recommended
For all other premises, the use of AFDDs conforming to BS EN 62606 is recommended for single-phase AC final circuits supplying socket outlets not exceeding 32A.


Locations where AFDDs are not required
Medical locations groups 1 and 2 are not required to be installed. Group 0 is subject to risk assessment.

From regulation 433.3.3 omission of devices for protection against overload for safety reasons, AFDDs may be omitted where unexpected disconnection of the circuit could cause danger. A safety alarm circuit is an example of one such circuit. 


Coordination of AFDDs with upstream distribution overcurrent protection devices circuits needs to consider RCD and MCB protection. If the AFDD is combined with all three protection levels and if necessary, shall take account of the manufacturer's instructions.

Arc Fault Detection
& Amendment 2

AFDDs are an important point of discussion:

What do they do? How do you know they will work? How do you test them? How do you know if they have failed?  Where do you install them? 

AFDDs are designed with one purpose only:

To detect arc faults where cables and connected appliances have damaged or broken line conductors, loose connections or failing connection points that enable arcs to generate across these failed points of the circuit. 

AFDDs have not been designed to detect low impedance, high current short circuits line to earth or line to neutral, overloaded circuits, and earth leakage on circuits. This is the role of Miniature Circuit Breakers (MCBs) and Residual Current Devices (RCDs).


If there is no arc generated that is identified as generating high enough energy to cause combustion, the AFDD will not operate. The AFDD’s internal processor analyses numerous parameters, voltage, current, waveform, duration of arc and irregularity of arc and will make a decision as to whether to add this or not into the processor unit every 10ms, or ½ cycle 50 Hz.


When the set number of potentially dangerous arcs have been added to the processor, the AFDD will activate and remove the supply from the circuit.  AFDDs are required to detect a potential cause of a fire that cannot be detected by existing installed devices, MCBs and RCDs.


In addition, AFDDs may also have an LED indicator incorporated within the body of the device to provide an indication of the detected fault. This will ultimately lead to less time trying to find the fault and guide the contractor to the cause.  

AFDDs are designed to perform a self-test as soon as power is present on the circuit.  And to perform this test at least every 24 hours while in operation.  The BG AFDD performs this test every hour, the LED will provide an indication if any part of the AFDD detection circuit has failed.

The AFDD is designed to monitor for arc faults - a broken connection in a ring circuit will not develop an arc fault, as both sides of the break in the ring conductor are at the same, or at a very similar voltage potential. Even when the line conductor in a ring is broken, the AFDD is still able to perform its intended purpose, however, the MCB may (is) not. 
AFDDs are designed to monitor and disconnect supply if serious arc faults are detected in a circuit - series and parallel arc faults, as described within BS7671 regulation.

For premises where AFDDs are a recommendation, the decision to offer increased protection to each and every person to the best of the contractor’s knowledge should be at the forefront of any decision making.




BG Electrical offers a range of high integrity, populated RCBO consumer units and A-Type devices to meet the new regulations.

See the range here:

For more information on A Type RCD’s, view our webinar HERE

531.3.2 Unwanted tripping, new indent (ii)

Residual current protective devices shall be selected and erected such as to limit the risk of unwanted tripping. The following shall be considered:

  1. Subdivision of circuits with individual associated RCDs. RCDs shall be selected and the circuits subdivided in such a way that any earth leakage current likely to occur during normal operation of the connected load will not cause unwanted tripping of the device. See also section 314

  2. The use of RCBOs for individual final circuits in residential premises. See also section 314.

  3. In order to avoid unwanted tripping by protective conductor currents and/or earth leakage currents, the accumulation of such currents downstream of the RCD shall be not more than 30 % of the rated residual operating current

NOTE 1:  This will also allow a better selection of the type of RCDs according to the nature of the circuit or the load.

NOTE 2:  RCDs may operate at any value of residual current in excess of 50 % of the rated residual current

For indent ii) above, this change is driven by the need to consider the connected loads. Dual split load consumer units can’t be organized effectively or efficiently to deal with the modern use of technology and modern lifestyle.

What are the changes?

Future changes should also be considered to accessories as we look to the smart home.  More electronics can result in more earth leakage and more RCD tripping on group circuits.

531.3.3 Types of RCD’s

(i)         RCD Type AC

(ii)        RCD Type A

(iii)       RCD Type F

(iv)       RCD Type B


RCD Type AC shall only be used to serve fixed equipment, where it is known that the load current contains no DC components.

NOTE 1:  Examples of fixed equipment with a load current containing no DC components can include but not be limited to electric heating appliances and/or simple filament lighting, neither containing electronic components.

Further Amendment 2 Changes

642.3 The inspection now includes earth electrodes where applicable, see (c) fault protection. 

643 has been redrafted

643.3.1 describes what conductor testing is required between live and live to earth:

The insulation resistance shall be measured between:

(i) live conductors, and

(ii) live conductors and the protective conductor connected to the earthing arrangement. During this measurement, line and neutral conductors may be connected

643.3.2 still applies and where all the parts of the installation can be tested using table 6 with minimum requirements of 1 (MΩ) at 500V DC.

But with the array of electronics now installed as part of the fixed wiring, testing must be performed on the initial cable installation in 1st fix and before the 2nd fix.

643.3.3 has added an allowance for testing at 250V DC.

The requirements for testing insulation resistance where connected equipment is likely to influence the verification test or the damaged has been clarified and reference is made to using a 250V DC applied to the live conductors, connected to the earthing arrangement with a minimum requirement of 1 (MΩ) at 250VDC.

Manufacturers’ instructions may recommend some equipment to be disconnected during 250V DC insulation resistance tests, as it may influence the results of the test.

643.7 Protection by Automatic Disconnection of Supply (ADS) (TN & TT Systems)

643.7.1 The requirements for verification of RCDs effectiveness have been changed and Table 3A (time/current performance criteria for (RCDs) in Appendix 3 has been deleted


Note: Regardless of RCD Type, effectiveness is deemed to have been verified where an RCD disconnects within the time stated below with an alternating current test at rated residual operating current (IΔn)

  • For general non-delay type, 300 m/s maximum

  • For delay ‘S’ type RCD, between 130 m/s minimum and 500 m/s maximum


643.8 Additional protection

Note: Regardless of RCD Type, effectiveness is deemed to have been verified where an RCD disconnects within the time stated below with an alternating current test at rated residual operating current (IΔn):

For general non-delay type, 300 m/s maximum

Other Changes

Section 514 - Identification and notices

This section contains a number of significant changes (including illustrations of notices have been removed and examples are provided in Appendix 11):


  • Labels moved

  • Letter and numeral size defined

  • No need to add labels to external sides of a consumer unit in residential and similar installations, where the exception is detailed 

  • Consumer units still requires label where two supplies are present, PV and DNO for example



“The requirements of this regulation need not be applied for domestic (household) premises or similar installations where certification for initial verification, complete with Guidance for Recipients as detailed in Appendix 6, has been issued to the person ordering the work.”





The Fortress circuit protection range from BG is about to launch its most extensive upgrade yet, with the latest improvements dovetailing the new guidelines around the 18th Edition Wiring Regulations, Amendment 2

These improvements have been made with the help of trusted installers working with our product development experts to help meet these regulation changes, with the aim of helping the installer complete their installations as quickly and efficiently as possible.

01952 238 100   I

Luceco Group, Stafford Park 1, Telford, Shropshire TF3 3BD

2022 Luceco Group   I    Privacy Policy   I   Contact

bottom of page