BS7671 18th Edition Draft out for comment

Here is a OCR grab of the summary of changes:

A summary of the main changes is given below. NOTE: 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 This Section contains a number of significant changes. Some of the main ones are mentioned below.

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).

Metallic pipes entering the building having an insulating section at their entrance need not be connected to the protective equipotential bonding.

Regulation 411.3.3 has been revised and now applies to socket-outlets with a rated current not exceeding 32 A. The exception to omit RCD protection for a specific labeled socket outlet or where, other than a dwelling, a documented risk assessment determines that RCD protection is not necessary has been deleted. The Regulation now requires RCD protection for all socket outlets.

A new Regulation 411.3.4 requires 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 the PEN conductor.

Regulation 411.44 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 newr Regulation 421.7 has been introduced for the installation of arc fault detection devices (AFDDs) to mitigate the risk of fire in final circuits of a fixed installation due to the effect of arc fault currents.

Regulation 422.2.1 has been redrafted to take into account the requirements of the European Construction Regulations (CPR) which defines specific provisions necessary for all wire and cables permanently installed in Construction Work. Regulation 422.3.4 has also been modified to refer only to fire performance classes (Euroclasses).

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 overvoltage is needed is no longer be included in BS 7671. Instead, protection against transient overvoltage has to be provided where the consequence caused by overvoltage affects human life, public services and cultural heritage, and commercial or industrial activity. 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 which prevent or remove 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 giving requirements for the methods of support of wiring systems in escape routes has been replaced by a new Regulation

Chapter 53 Protection, isolation, switching, control and monitoring This Chapter has been completely revised and deals with general requirements for 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. The most significant technical change refers to the selection requirements for the voltage protection level.

Chapter 54 Earthing arrangements and protective conductors Regulation 542.1.201 has been modified and now requires an additional earth electrode, supplementing any earthing facility provided by the distributor. Two new regulations (542.2.3 and 542.2.8) have been introduced concerning foundation earth electrodes. Two new regulations (543.3.3.101 and 543.3.3.102) have been introduced. These give requirements for the insertion of a switching device ir protective conductor in situations where an installation is supplied from more than one source of energy.

Chapter 55 Other equipment Regulation 550.1 introduces a new scope. Regulation 559.10 Ground-recessed luminaires. For group-recessed luminaires, the selection and erection shall take account of the guidance given in Table A.l of BS EN 60598-2-13. Part 6 Inspection and testing Part 6 has been completely restructured including the numbering to align with the CENELEC standard. Chapter 61,62, and 63 have been deleted and the content of these chapters have been moved to Chapter 64 and Chapter

Section 704 Construction and demolition site installations This Section contains a number of small changes including requirements for external influences, and modifications to Regulation 704.410.3.6 concerning the protective measures of obstacles and placing out of reach and 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 Table 710, Regulation 710.415.2.1 and 710.415.2.3 concerning equipotential bonding.

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 a significant change 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 a completely new Section. This Section applies to onshore installations dedicated to the supply of inland navigation vessels for commercial and administrative purpose, berthed in ports and berths. Most, if not all, of the measures used to reduce the risks in marinas equally apply for 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. They 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 TEC 60519, IEC 62395 and IEC 60079 are not covered.

Part 8 Energy efficiency This is a completely new Part. The worldwide need to reduce the consumption of energy means that we have to consider how electrical installations can provide the required level of service and safety for the lowest electrical consumption. Part 8 enables a client to specify the level of energy efficiency measures applied to an electrical installation. Installations can also be awarded points for energy efficiency performance levels. The new Part covers several energy efficient areas, such as lighting, metering, cable losses, transformer losses, power- factor correction, and harmonics.

The follow main changes have been made within the appendices:

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

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

Does that mean all TN-S and TN-C-S will require retro-fitting of an earthing rod?

Building Regs are not retrospective.

Some IET Regs are - eg bonding and earthing must be brought up to spec when anything electrical is worked on.

I saw comments on that in April on the earlier draft of changes on the lines of "Bound to be a controversial subject!".

But I think TN-S is OK; it's about PME (TN-S) where broken neutrals are

- allegedly - increasing.

Bugger: the second TN-S should be TN-C-S

(My emphasis)

Which suggests it applies all earthing types - even TT!

Is operating a 1st edition install legal?

NT

Ah, right, thanks.

And this being the BS7671 lot I don't suppose they have published their impact assessment for this - you know the kind of thing, with figures for costs and benefits and the like.

Sheesh, if it were real legislation (instead of just "tertiary legislation" 'cos in practice it has to be followed) they'd never get away with it.

I would guess if that comes (*if*) it would be after this consultation exercise...

Na, just criminally insane... ;-)

The point was, if you carry out modifications to a system that was compliant with the 1st edition at the time of installation, then all new work will still need to comply with current legislation, and also, there are aspects of the existing installation that must be brought up to current standards, even if the new work would not directly affect them.

Yerrbut...they have form on not publishing their workings (eg on metal CUs).

And as you'll know, given the data and the assumptions behind a proposed change people can comment on those as well as the change itself (as with the original Part P where people pointed out the impact assessment scored deaths by electrocution from appliances). If they only publish them after consultation then it's too late to affect decisions.

As it is, I have no idea if the driving force is the safety of consumers, let alone the cost per quality adjusted life year or whatever. It might for all I know be DNOs wanting to avoid paying compensation for damage to property. And they might be very happy for consumers to pay £m25 a year to save them £m5 a year.

Sorry. Here endeth my rant.

I would say it discounts the TT as TT has no distributors earthing facility.

Define "anything electrical is worked on"

BTW I forgot, almost everything must be now RCD protected because it's SO much safer. But don't worry RCDs NEVER fail and they are ALL tested every 3 months with the test button by the occupiers of the house and every 10 years by an electrician doing an EICR.

The 19th edition (or maybe the 18th 3rd amendment) will bring back bathroom supplementary bonding. I believe it was John Rumm that once said "a bit of 4mm cable and a couple of earth clamps are almost bullet proof"

Cheers

Changing the battery in the customer's vibrator ;-)

In the case of part P though, a very different "they". Part P was a government driven thing championed by Precott - not IET lead.

Indeed, or just to keep revenue flowing in from sales of the big (insert colour of choice) book!

Yup perhaps, its not that well worded since they quote "542.1.2.1 to 3" where 3 is TT...

I don't think that that the ones in Lou's are changeable.

It's a sealed unit (dishwasher proof) and the batteries are charged by induction.