Tag Archives: BS 7671:2018

Amendment number 1 to BS 7671:2018+A1

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Amendment 1 of BS 7671:2018 was published at the beginning of February this year and may be implemented immediately. The amendment concerns Section 722 of BS 7671:2018 (electric vehicle charging installations). In this article, we give a brief overview of some of the main changes to Section 722.

Protection against electric shock

Regulation 722.411.4.1 concerning the use of protective multiple earthing (PME) supply has been redrafted. Indent (iii) has been fully revised. In addition, Regulation 722.411.4.1 now includes an additional indent (iv) to cover single-phase installations and a further additional indent (v) has been added. Regulation 722.411.4.1 does not allow PME to be used to supply an electric vehicle (EV) charging point located outdoors (or that might be used to charge a vehicle located outdoors) unless you meet (i) or (ii) or (iii) or (iv) or (v) of 722.411.4.1.

A summary of the requirements of the indents to Regulation 722.411.4.1 is as follows.

Regulation 722.411.4.1(i) refers to a situation where a connecting point is supplied from a three-phase installation used to supply loads other than charging points and where the load is sufficiently well balanced.

Regulation 722.411.4.1(ii) requires a very low resistance earth electrode to mitigate the effects of an open-circuit (PEN) conductor fault on the supply.

Regulation 722.411.4.1 (iii) has been revised and refers to a voltage monitoring device (or functionality within the charging equipment) that detects PEN conductor failure. The informative Annex to Section 722 describes that suitable arrangements include measurement of the voltage between either:

   a. the circuit protective conductor (CPC) and a suitable measurement earth electrode, or
   b. the CPC and a reference point derived from the line conductors of a three-phase system provided that suitable precautions are also taken to disconnect the device when the supply to one or more of the line conductors is interrupted.

Regulation 722.411.4.1 now includes an additional new indent (iv) to cover protection by a device (or functionality within the charging equipment) for a single-phase installation.

Finally, Regulation 722.411.4.1 includes an additional new indent (v), which allows protection against electric shock to be provided by the use of an alternative device to those in (iii) or (iv), providing that it does not result in a lesser degree of safety than using (iii) or (iv). The indent states that equivalent means of functionality could be included within the charging equipment.

The touch voltage threshold of 70 V mentioned in Regulation 722.411.4.1 is on the basis that Table 2c (ventricular fibrillation for alternating current 50/60 Hz) of IEC 60479-5{ed1.0} gives a value of 71 V for both-hands-to-feet, in water-wet conditions with medium contact area (12.5 cm2).

Regulation 722.411.4.1 includes some important notes. Note 5 explains that BS 7671 does not deal with the safety requirements for the construction of electrical equipment. Where equipment to be used is not covered by a British or Harmonized Standard, the electrical installation designer should establish that the manufacturer of the equipment has ensured that the equipment satisfies the safety objectives of the relevant directive(s).

Note 6 states that creating a TT earthing system for charging equipment or for the whole installation, as an alternative to using a PME earthing facility with one of methods (i) to (v) above, may not be an appropriate solution, due to the inability to provide sufficient separation from buried metalwork connected to the supply PEN conductor.

What is protective multiple earthing (PME)?

The Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR) (as amended) permit the distributor to combine neutral and protective functions in a single conductor, provided that (in addition to the neutral to Earth connection at the supply transformer) there are one or more other connections with Earth. The supply neutral may then be used to connect the CPCs of the customer’s installation with Earth if the customer’s installation meets the requirements of BS 7671.

PME has been almost universally adopted by distributors in the UK as an effective and reliable method of providing their customers with an earth connection. Such a supply system is described in BS 7671 as TN-C-S. However, whilst a PME terminal provides an effective and reliable facility for the majority of installations, under certain supply system fault conditions (external to the installation), a potential can develop between the conductive parts connected to the PME earth terminal and the general mass of Earth.

The potential difference between true Earth and the PME earth terminal is of importance when:

   a. body contact resistance is low (little clothing, damp/wet conditions), and/or
   b. there is relatively good contact with true Earth. 

Contact with Earth is always possible outside a building and, if exposed-conductive-parts and/or extraneous-conductive-parts connected to the PME earth terminal are accessible outside the building, people may be subjected to a voltage difference appearing between these parts and Earth.

Residual current device (RCD) protection

The requirements for RCD protection have been redrafted. The Regulation now contains further requirements for Type B and Type A or Type F RCDs, to take account of DC fault current, as follows (extract below):

“Except where provided by the EV charging equipment, protection against DC fault currents shall be provided by:

(i) an RCD Type B, or

(ii) an RCD Type A or Type F in conjunction with a residual direct current detecting device (RDC-DD) complying with BS IEC 62955 as appropriate to the nature of the residual and superimposed currents and recommendation of the manufacturer of the charging equipment.”

ANNEX A722 (Informative)

Annex A722 has been redrafted. This Annex now includes guidance on the voltage monitoring device described in Regulation 722.411.4.1 (iii). In addition, the Annex now includes an example arrangement of a separated system as described in Regulation 722.413. 

Conclusion

It is important to note that this article gives only a very brief overview of some of the changes in the Amendment to BS 7671:2018. For more information, please refer to BS 7671:2018, Amendment 1:2020.

By: Geoff Cronshaw – IET Wiring Matters – Issue 79

BS 7671:2018 – Section 708 (caravan/camping parks) And Section 721 (caravan and motor caravans)

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Section 708 caravan/camping parks

This particular requirement of 708 applies to the electrical installations in caravan/camping parks and similar locations providing connection points for supplying leisure accommodation vehicles (including caravans) and tents.

The scope of Section 708 has been extended to cover circuits intended to supply residential park homes in caravan parks, camping parks and similar locations. In addition changes have been made to socket outlet requirements, RCD protection, and external influences.

Protection against electric shock

General requirements

As you would expect the protective measures of obstacles; placing out of reach, in a non-conducting location and protection by earth-free local equipotential bonding are not permitted. These measures are contained in Sections 417 and 418 of BS 7671:2008 and are not for general application. The protective measures of section 417 provide basic protection only and are for application in installations controlled or supervised by skilled or instructed persons. The fault protective provisions of Section 418 are special and, again, subject to control and effective supervision by skilled or instructed persons.

Protective multiple earthing

As stated in Regulation 708.411.4 The Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR) prohibit the connection of a PME earthing facility to any metalwork in a leisure accommodation vehicle (including a caravan).

This does not preclude the use of a PME earthing facility as the means of earthing for other purposes, such as to the installations of permanent buildings.

External influences

Any wiring system or equipment selected and installed must be suitable for its location and able to operate satisfactorily during its working life. Suitable protection must be provided, both during construction and for the completed installation. Regarding presence of solid foreign bodies, a minimum degree of protection of IP4X is now required. Regarding presence of water a minimum degree of protection of IPX4 is required.

Equipment must be protected against mechanical impact IK 08 (see BS EN 62262) and/or located to avoid damage by any reasonable foreseeable impact.

Caravan pitch socket-outlets

The requirements for socket outlets have been redrafted to prevent the socket contacts being live when accessible.

Regulation 708.55.1.1 requires that every socket-outlet or connector shall either comply with:

  1. a) BS EN 60309-2 and shall be interlocked and classified to clause 6.1.5 of BS EN 60309-1:1999 to prevent the socket contacts being live when accessible; or

 

  1. b) – be part of an interlocked self-contained product complying with BS EN 60309-4 and classified to clauses 6.1.101 and 6.1.102 of BS EN 60309-4:2006 to prevent the socket contacts being live when accessible.

The current rating is to be not less than 16 A but may be greater if required. At least one socket-outlet should be provided for each caravan pitch. Where socket-outlets are grouped in pitch supply equipment, there should be one socket-outlet for each pitch limited to a group of four.

 Overcurrent protection

Every socket-outlet shall be individually protected by an overcurrent protective device, in accordance with the requirements of Chapter 43.

A fixed connection for a supply to a mobile home or residential park home shall be individually protected by an overcurrent protective device, in accordance with the requirements of Chapter 43.

Isolation

Regulation 708.537.2.1.1 now requires at least one means of isolation to be installed in each distribution enclosure. This device shall disconnect all live conductors.

RCD protection

Each socket-outlet must be protected individually by an RCD having a rated residual operating current not exceeding 30mA. The RCD must disconnect all live conductors including the neutral.

Requirements for RCD protection have been extended to cover supplies to residential park homes. A final circuit (from the metering point) intended for the

fixed connection for a supply to a mobile home or a residential park home shall be individually protected by an RCD having a rated residual operating current not exceeding 30 mA accessible to the consumer. Devices selected shall disconnect all live conductors.

PME

As mentioned previously, the ESQCR prohibit the connection of a PME earthing facility to any metalwork in a leisure accommodation vehicle (caravan). If the caravan supply is derived from a permanent building that is supplied by a PME system then the caravan supply will have to be part of a TT system having a separate connection to Earth independent from the PME earthing.

The separation of the earthing can be effected at the main distribution board. The IET’s Guidance Note 7 publication Special Locations provides detailed information. This enables the exposed-conductive-parts connected to each system to be more readily identified and inspected periodically. An earth electrode for the TT system should be provided nearby and located so that the resistance areas of the PME supply earthing and earth electrode do not overlap.

Alternatively, the separation of the earthing can be made at the caravan pitch supply points. In this instance, earth electrodes will be required at these points.

Again, The IET’s Guidance Note 7 provides detailed information.

Section 721 caravans and motor caravans

The particular requirements of 721 apply to the electrical installations of caravans and motor caravans at nominal voltages not exceeding 230/440 V AC or 48 V DC

Note there are some exceptions.

This section contains a number of changes including requirements for electrical separation, RCDs, proximity to non-electrical services, and protective bonding conductors.

Protective equipotential bonding

Regulation 721.411.3.1.2 requires structural metallic parts that are accessible from within the caravan to be connected through main protective bonding conductors to the main earthing terminal within the caravan.

The requirements for connections of protective bonding conductors have been clarified. Regulation 721.544.1.1 states that the terminations of protective bonding conductors connecting the conductive structure of the unit shall be accessible and protected against corrosion.




Provision of RCDs

The requirements for RCD protection have also been redrafted.

Regulation 721.415.1 states that where protection by automatic disconnection of supply is used, a residual current device with a rated residual operating current not exceeding 30 mA, complying with BS EN 60947-2 (Annex B), BS EN 61008-1, BS EN

61009-1 or BS EN 62423 breaking all live conductors, shall be provided having the characteristics specified in 415.1.1.

Each supply inlet shall be directly connected to its associated RCD.

Please note this implies that there may not be any taps or junctions in this connection.

An RCD is a protective device used to automatically disconnect the electrical supply when an imbalance is detected between live conductors. In the case of a single-phase circuit, the device monitors the difference in currents between the line and neutral conductors. If a line to earth fault develops, a portion of the line conductor current will not return through the neutral conductor. The device monitors this difference, operates and disconnects the circuit when the residual current reaches a preset limit, the residual operating current (IΔn).

Proximity to non-electrical services

The requirements for proximity to non-electrical services have been redrafted.

Regulation 721.528.2.1 requires that where cables have to run through a gas cylinder storage compartment, they shall pass through the compartment at a height of not less than 500 mm above the base of the cylinders and shall be protected against mechanical damage by installation within a conduit system complying with the appropriate part of the BS EN 61386 series or within a ducting system complying with the appropriate part of the BS EN 50085 series.

Switchgear and controlgear

The installation to the caravan should have a main disconnector, which will disconnect all the live conductors. This should be placed in a suitable position for ready operation within the caravan to isolate the supply. When a caravan only has one final circuit then the isolation can be afforded by the overcurrent protective device as long as it fulfils the requirements for isolation.

An indelible notice in the appropriate language(s) must be permanently fixed near the main isolation point inside the caravan to provide the user with instructions on connecting and disconnecting the supply (refer to Figure 721 of BS 7671).

The inlet to the caravan must be an appliance inlet complying with BS EN 60309-1. This should be installed not more than 1.8 m above ground level, in a readily accessible position, have a minimum degree of protection of IP44, and should not protrude significantly beyond the body of the caravan.

The connecting flexible cable

The means of connecting the caravan to the pitch socket-outlet should be provided with the caravan. This must have a plug at one end complying with BS EN 60309-2, a flexible cable with a continuous length of 25 m (±2 m). The connecting flexible cable must be in one length, without signs of damage, and not contain joints or other means to increase its length; and a connector if needed that is compatible with the appropriate appliance inlet. The cable should be to the harmonized code H05RN-F (BS EN 50525-2-21) or equivalent, include a protective conductor, have cores coloured as required by Table 51 of BS 7671 and have a cross-sectional area as shown in Table 721.

Periodic inspection & testing

The purpose of periodic inspection and testing is to provide an engineering view on whether or not the installation is in a satisfactory condition where it can continue to be used safely. Periodic inspection and testing is necessary because all electrical installations deteriorate due to a number of factors such as damage, wear, tear, corrosion, excessive electrical loading, ageing and environmental influences. IET Guidance Note 3 gives the recommended initial frequencies for inspection of electrical installations for construction sites, caravan/camping parks, and in caravans.

Conclusion

It is important to be aware that this article (which is based on an article from Issue 67 of Wiring Matters) only gives a brief overview of requirements for electrical installations on caravan/camping parks, and in caravans. Refer to BS 7671:2018 for more information.

Order Now – Eighteenth Edition – BS 7671:2018 (Electrical Regulations)

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You can now order your copy of the Requirements for Electrical Installations, IET Wiring Regulations, Eighteenth Edition, BS 7671:2018 (Electrical Regulations) and the On-Site Guide (BS 7671:2018) (Electrical Regulations) 

Requirements for Electrical Installations, IET Wiring Regulations, Eighteenth Edition, BS 7671:2018 (Electrical Regulations)

The IET Wiring Regulations are of interest to all those concerned with the design, installation and maintenance of electric wiring in buildings. The market includes electricians, electrical contractors, consultants, local authorities, surveyors and architects. This book will also be of interest to professional engineers, as well as students at university and further education colleges. All users of the IET Wiring Regulations need to be aware of the coming changes in the 18th Edition (BS 7671:2018). This is intended to come into effect on 1st January 2019, although industry needs to start preparing for this from its point of publication (2nd July 2018).

On-Site Guide (BS 7671:2018) (Electrical Regulations) Spiral-bound – 2 Jul 2018

The On-Site Guide is an essential guide to BS 7671. It incorporates the extensive changes in BS 7671:2018, making this a vital guide for keeping up to date. It enables the competent electrician to deal with installations (up to 100 A, 3-phase) providing essential information in a convenient, easy-to-use format. The 18th Edition IET Wiring Regulations publishes in July 2018 and comes into effect on 1st January 2019. All new installations from this point must comply with BS 7671:2018.

     

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The Main Changes In The 18th Edition IET Wiring Regulations

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The following list provides an overview of the main changes within the 18th Edition IET Wiring Regulations (publishing 2nd July 2018). This list is not exhaustive as there are many smaller changes throughout the book not included here.BS 7671:2018 Requirements for Electrical Installations will be issued on 2nd July 2018 and is intended to come into effect on 1st January 2019.

Installations designed after 31st December 2018 will have to comply with BS 7671:2018.

The Regulations apply to the design, erection and verification of electrical installations, also additions and alterations to existing installations. Existing installations that have been installed in accordance with earlier editions of the Regulations may not comply with this edition in every respect. This does not necessarily mean that they are unsafe for continued use or require upgrading.

A summary of the main changes is given below. (This is not an exhaustive list).

Part 1 Scope, object and fundamental principles

Regulation 133.1.3 (Selection of equipment) has been modified and now requires a statement on the Electrical Installation Certificate.

Part 2 Definitions

Definitions have been expanded and modified.

Chapter 41 Protection against electric shock

Section 411 contains a number of significant changes. Some of the main ones are mentioned below:

Metallic pipes entering the building having an insulating section at their point of entry need not be connected to the protective equipotential bonding (Regulation 411.3.1.2).

The maximum disconnection times stated in Table 41.1 now apply for final circuits up to 63 A with one or more socket-outlets and 32 A for final circuits supplying only fixed connected current-using equipment (Regulation 411.3.2.2).

Regulation 411.3.3 has been revised and now applies to socket-outlets with a rated current not exceeding 32A. There is an exception to omit RCD protection where, other than a dwelling, a documented risk assessment determines that RCD protection is not necessary.

A new Regulation 411.3.4 requires that, within domestic (household) premises, additional protection by an RCD with a rated residual operating current not exceeding 30 mA shall be provided for AC final circuits supplying luminaires.

Regulation 411.4.3 has been modified to include that no switching or isolating device shall be inserted in a PEN conductor.

Regulations 411.4.4 and 411.4.5 have been redrafted.

The regulations concerning IT systems (411.6) have been reorganized. Regulations 411.6.3.1 and 411.6.3.2 have been deleted and 411.6.4 redrafted and a new Regulation 411.6.5 inserted.

A new Regulation group (419) has been inserted where automatic disconnection according to Regulation 411.3.2 is not feasible, such as electronic equipment with limited short-circuit current.

Chapter 42 Protection against thermal effects

A new Regulation 421.1.7 has been introduced recommending the installation of arc fault detection devices (AFDDs) to mitigate the risk of fire in AC final circuits of a fixed installation due to the effects of arc fault currents.

Regulation 422.2.1 has been redrafted. Reference to conditions BD2, BD3 and BD4 has been deleted. A note has been added stating that cables need to satisfy the requirements of the CPR in respect of their reaction to fire and making reference to Appendix 2, item 17. Requirements have also been included for cables that are supplying safety circuits.

Chapter 44 Protection against voltage disturbances and electromagnetic disturbances

Section 443, which deals with protection against overvoltages of atmospheric origin or due to switching, has been redrafted.

The AQ criteria (conditions of external influence for lightning) for determining if protection against transient overvoltages is needed are no longer included in BS 7671. Instead, protection against transient overvoltages has to be provided where the consequence caused by overvoltage (see Regulation 443.4)

(a) results in serious injury to, or loss of, human life, or
(b) results in interruption of public services/or damage to and cultural heritage, or
(c) results in interruption of commercial or industrial activity, or
(d) affects a large number of co-located individuals.

For all other cases, a risk assessment has to be performed in order to determine if protection against transient overvoltage is required.

There is an exception not to provide protection for single dwelling units in certain situations.

Chapter 46 Devices for isolation and switching – A new Chapter 46 has been introduced.

This deals with non-automatic local and remote isolation and switching measures for the prevention or removal of dangers associated with electrical installations or electrically powered equipment. Also, switching for the control of circuits or equipment. Where electrically powered equipment is within the scope of BS EN 60204, only the requirements of that standard apply.

Chapter 52 Selection and erection of wiring systems

Regulation 521.11.201 which give requirements for the methods of support of wiring systems in escape routes, has been replaced by a new Regulation 521.10.202. This is a significant change.

Regulation 521.10.202 requires cables to be adequately supported against their premature collapse in the event of a fire. This applies throughout the installation and not just in escape routes.

Regulation 522.8.10 concerning buried cables has been modified to include an exception for SELV cables.

Regulation 527.1.3 has also been modified, and a note added stating that cables also need to satisfy the requirements of the CPR in respect of their reaction to fire.

Chapter 53 Protection, isolation, switching, control and monitoring

This chapter has been completely revised and deals with general requirements for protection, isolation, switching, control and monitoring and with the requirements for selection and erection of the devices provided to fulfil such functions.

Section 534 Devices for protection against overvoltage

This section focuses mainly on the requirements for the selection and erection of SPDs for protection against transient overvoltages where required by Section 443, the BS EN 62305 series, or as otherwise stated.

Section 534 has been completely revised and the most significant technical change refers to the selection requirements for the voltage protection level.

Chapter 54 Earthing arrangements and protective conductors

Two new regulations (542.2.3 and 542.2.8) have been introduced concerning earth electrodes.

Two further new regulations (543.3.3.101 and 543.3.3.102) have been introduced. These give requirements for the insertion of a switching device in a protective conductor, the latter regulation relating to situations where an installation is supplied from more than one source of energy.

Chapter 55 Other equipment

Regulation 550.1 introduces a new scope.

New Regulation 559.10 refers to ground-recessed luminaires, the selection and erection of which shall take account of the guidance given in Table A.1 of BS EN 60598-2-13.

Part 6 Inspection and testing

Part 6 has been completely restructured, including the regulation numbering to align with the CENELEC standard.

Chapters 61, 62 and 63 have been deleted and the content of these chapters now form two new Chapters 64 and 65.

Section 704 Construction and demolition site installations

This section contains a number of small changes, including requirements for external influences (Regulation 704.512.2), and a modification to Regulation 704.410.3.6 concerning the protective measure of electrical separation.

Section 708 Electrical installations in caravan/camping parks and similar locations

This section contains a number of changes including requirements for socket-outlets, RCD protection, and operational conditions and external influences.

Section 710 Medical locations

This section contains a number of small changes including the removal of Table 710.

Changes to Regulations 710.415.2.1 and 710.415.2.3 concerning equipotential bonding.

A new Regulation 710.421.1.201 which states for all final circuits supplied by medical IT system in medical locations of group 2, AFDD shall not be used.

Section 715 Extra-low voltage lighting installations

This section contains only minor changes including modifications to Regulation 715.524.201.

Section 721 Electrical installations in caravans and motor caravans

This section contains a number of changes including requirements electrical separation, RCDs, proximity to non-electrical services and protective bonding conductors.




Section 722 Electric vehicle charging installations

This section contains significant changes to Regulation 722.411.4.1 concerning the use of a PME supply.

The exception concerning reasonably practicable has been deleted.

Changes have also been made to requirements for external influences, RCDs, socket-outlets and connectors.

Section 730 Onshore units of electrical shore connections for inland navigation vessels

This is an entirely new section and applies to onshore installations dedicated to the supply of inland navigation vessels for commercial and administrative purposes, berthed in ports and berths.

Most, if not all, of the measures used to reduce the risks in marinas apply equally to electrical shore connections for inland navigation vessels. One of the major differences between supplies to vessels in a typical marina and electrical shore connections for inland navigation vessels is the size of the supply needed.

Section 753 Floor and ceiling heating systems

This section has been completely revised.

The scope of Section 753 has been extended to apply to embedded electric heating systems for surface heating.

The requirements also apply to electric heating systems for de-icing or frost prevention or similar applications, and cover both indoor and outdoor systems.

Heating systems for industrial and commercial applications complying with IEC 60519, IEC 62395 and IEC 60079 are not covered.

Appendices

The following main changes have been made within the appendices

Appendix 1 British Standards to which reference is made in the Regulations includes minor changes, and additions.

Appendix 3 Time/current characteristics of overcurrent protective devices and RCDs

The previous contents of Appendix 14 concerning earth fault loop impedance have been moved into
Appendix 3.

Appendix 6 Model forms for certification and reporting

This appendix includes minor changes to the certificates, changes to the inspections (for new installation work only) for domestic and similar premises with up to 100 A supply, and examples of items requiring inspection for an electrical installation condition report.

Appendix 7 (informative) Harmonized cable core colours

This appendix includes only minor changes.

Appendix 8 Current-carrying capacity and voltage drop

This appendix includes changes regarding rating factors for current-carrying capacity.

Appendix 14 Determination of prospective fault current

The contents of Appendix 14 concerning earth fault loop impedance have been moved into
Appendix 3. Appendix 14 now contains information on determination of prospective fault current.

Appendix 17 Energy efficiency

This is a new appendix that provides recommendations for the design and erection of electrical installations including installations having local production and storage of energy for optimizing the overall efficient use of electricity.

The recommendations within the scope of this appendix apply for new electrical installations and modification of existing electrical installations. Much of this appendix will not apply to domestic and similar installations.

It is intended that this appendix is read in conjunction with BS IEC 60364-8-1, when published in 2018

Information via – theiet.org

Pre-Order Your Copy Of BS 7671:2018 (18th Edition Regs)

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Requirements for Electrical Installations, IET Wiring Regulations, Eighteenth Edition, BS 7671:2018 (Electrical Regulations)

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On-Site Guide (BS 7671:2018) (Electrical Regulations) 

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Release date 1st July 2018.

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