17th edition mk sentry solutions · of bs7671: 2008, the 17th edition of the institute of...

17th Edition MK Sentry Solutions


Currently the national safety standard for electrical installation

work in the UK is British Standard 7671 – Requirements for

Electrical Installations. The IEE Wiring Regulations are a code

of practice for ensuring safe electrical installations.

Although the IEE Wiring Regulations have no statutory force

in the UK, they are referred to as a means of demonstrating

compliance with relevant legislation, such as the Electricity at

Work Act (1989) and the Building Regulations.

After approximately three years of consultation and drafting, January 2008 saw the introduction

of BS7671: 2008, the 17th Edition of the Institute of Electrical Engineers Wiring Regulations.

After an initial 6 month transitional period, the new regulations will come into full effect from

the 1st July 2008.

The regulations have been updated to further harmonize with International and European standards. The process of European

harmonization had already begun with the previous amendments to the 16th Edition, most notably the changes in cable

insulation colours. The 17th Edition maintains harmonization with the International Standard (IEC 60364) and the related

European Harmonization Document (HD 384) from the European Committee for Electrotechnical Standardisation (CENELEC),

which results in:

l Renumbering

l Restructuring

l New regulations

l Removal of some existing regulations

After approximately three years of consultation and drafting, January 2008 saw the introduction

of BS7671: 2008, the 17th Edition of the Institute of Electrical Engineers Wiring Regulations.

After an initial 6 month transitional period, the new regulations will come into full effect from

the 1st July 2008.

An example of European harmonization was the changes to cable insulation colours in the

amendments to the 16th Edition in 2004

The biggest change from the 16th to the 17th Edition

is increased use of Residual Current Devices. Previously,

RCDs have only been required to protect socket outlets

for use outdoors, where disconnection times can not be

achieved, and special locations. With the introduction of the

17th Edition, this is set to change.

The term ‘Additional Protection’ is used throughout the

publication. The use of RCDs are recognised as a means

of providing additional protection in the event of failure of

the provision for Basic Protection*, as an additional means

of Fault Protection*, and to protect against carelessness by

users. If an RCD is used to provide Additional Protection it

must then meet the requirements of Regulation 415.1.1.

That is, the RCD must have a rated residual operating current

not exceeding 30mA, and an operating time not exceeding

40ms at 5x the rated current.


The 17th Edition refers to various applications and

installations which require Additional Protection by the

means of the aforementioned RCD. The first of which is

found in Regulation 411.3.3, where Additional Protection is

required for:

i. Socket outlets with a rated current not exceeding 20A,

that are for use by Ordinary Persons* and intended for

general use

ii. Mobile equipment with a current rating not exceeding

32A for use outdoors

An exception to ‘i’ is permitted for:

a. Socket outlets for use under the supervision of Skilled* or

Instructed* Persons

b. A specific labelled or otherwise suitably identified socket

outlet provided for connection of a particular item of

equipment

An example of this occurrence would be if an installation was

overseen by facilities or maintenance operatives, as would

be the case in some commercial environments, but not in

domestic situations. Labelling could be interpreted as a

socket outlet marked ‘fridge’, ‘freezer’. ‘I.T. Equipment’ etc.

* This term is explained in the glossary at the end of this brochure.

Mobile equipment for use outdoors will require Additional Protection

Further requirements for Additional Protection next appear

in section 522 – Selection and Erection of Wiring Systems

in Relation to External Influences. 522.6.6 applies to cables

concealed in a wall or partition, at a depth of less than

50mm from the surface – as would be common practice in

most installations. Five installation methods are offered for

cables at a depth of less than 50mm.

i. The cable should incorporate an earthed metallic covering,

which acts as a circuit protective conductor (CPC)

ii. The cable should be enclosed in earthed conduit

iii. The cable should be enclosed in earthed trunking or

ducting

iv. The cable should be mechanically protected against

penetration by nails or screws

v. The cable should be installed in a safe zone*

This is very similar to the 16th Edition, however the next

Regulation, 522.6.7, states that where the installation

is not intended to be under the supervision of Skilled* or

Instructed* Persons, a cable installed in accordance with

method v, and not complying with methods i, ii, iii and iv shall

be provided with Additional Protection by means of an RCD

with an operating current not exceeding 30mA, reference

Regulation 415.1.1. Typically, a domestic installation,

and some commercial installations, would use cables with

thermoplastic (PVC) insulation that are not mechanically

protected or incorporate an earthed metallic covering.

Therefore, these cables would require RCD protection.

Irrespective of the depth of the cable, Regulation 522.6.8

requires that a cable is installed in a wall or partition, if the

construction of the wall or partition incorporates metallic

parts, the installation method must comply with methods

i - iv or be protected by means of a 30mA RCD.

* This term is explained in the glossary at the end of this brochure.

50mm

50mm

Stud partition wall

Brick / block and plaster wall

50mm

50mm

Stud partition wall

Brick / block and plaster wall

Concealed cables requiring RCD protection

Section 701 concerns locations containing a bath or shower.

It is now a requirement under 701.411.3.3 that additional

protection shall be provided for all circuits of the location

by the use of one or more RCDs, again, with an operating

current not exceeding 30mA, reference Regulation 415.1.1.

As well as items such as electric towel rails and electric

showers, this regulation also applies to lighting.

Although all of the aforementioned areas require RCD

protection, the requirements of Regulation 314.1, Division of

Installation, need to be taken into account, when designing

and installing the circuit protective arrangements. 314.1

states that every installation shall be divided into circuits as

necessary to:


a. Avoid hazards and minimise inconvenience in the event of

a fault

b. Take account of danger that may arise from the failure of

a single circuit such as a lighting circuit

c. Reduce the possibility of unwanted tripping of RCDs due

to excessive protective conductor currents produced by

equipment in normal operation

This means a single RCD cannot be used to protect the

whole installation, as in the event of a fault, power will be

lost to all circuits potentially causing hazards, inconvenience

and danger. Therefore multiple devices should be installed

to protect the outgoing circuits and should also be split

across the RCDs, alternatively the suitable installation of

RCBOs could be used to protect individual circuits. A split

arrangement would be ground floor and first floor lighting

circuits protected by separate RCDs. Another example would

be that the circuit which supplies the bathroom lighting

would be separately protected from that which supplies the

electric shower. A fault developing on the electric shower

circuit would then not affect the lighting circuit.

All circuits within a location containing a bath or shower will require Additional Protection

MK Sentry Consumer Units

Specific consumer unit configurations have been designed to provide flexible solutions in meeting

the requirements of the 17th Edition with regards to RCD protection for circuits, cables and

socket outlets. The new MK Sentry Consumer Units, available in insulated and metal versions,

allow for protected and unprotected ways with the circuits being split across up to 3 RCDs,

whilst a new labelling sheet allows for full identification of all circuits.

Factory Built AssemblyUsing standard MK Sentry components we can build and supply fully assembled units to an agreed design. For example have

your Consumer Units supplied with all the devices fitted, busbars cut and fitted with neutral and live cables terminated*.

For more information call the MK Technical Services Team on 01268 563720.

*minimum order quantity applies.

OptiOnAl lOCKing MEChAniSM

FluSh MOuntABlE OptiOnSFor an even neater installation

unitS CAn BE StACKED FOR lARgER inStAllAtiOnS

OpAquE AnD DOwnwARD OpEning liD Hides unsightly labels and devices

lOw pROFilE AnD CuRvED DESignBlends unobtrusively into the environment

COMpACt SiZEBut wiring space increased where required most

DiSCREEt MOulDED in lOgONo visible fixing screws

OFFSEt inCOMER Provides additional wiring space making mains input connections easier

BACKED Out AnD CAptivE COMBi-hEAD SCREwS Allows speedy installation

EASilY REMOvABlE Din-RAilImproves first fix

Fixing hOlES Allow tripod fixing to cope with uneven surfaces. Hole locations allow access for cordless drills and power drivers

AMplE wiRing SpACE

RAiSED Din-RAil For improved cable routing

AMplE 360º KnOCK-OutS FOR CABlE ROutingOpen cable entry at rear plus optional rear knock-outs

FlExiBlE nEutRAl BAR COnFiguRAtiOnEnables installer to select a wide combination of protected and unprotected circuits

FlOAting BuSBAR SYStEM For maximum installation flexibility including acceptance of control modules

COlOuR CODED EARth AnD nEutRAl tERMinAl lOCAtED At tOp OF unit FOR EASE OF wiRing


Split load board with RCBOsMK recommend the use of a split load board with RCBOs. An RCBO will provide individual over

current and earth leakage protection for an outgoing circuit. In the event of fault conditions the

supply will be disconnected only to the dedicated circuit. Standard configurations augmented

with RCBOs provide the optimum solution for additions and alterations. An MK RCBO is the

same width as an MK MCB, providing a reto-fittable solution for additions and alterations to

an existing installation.

IndIvIdual protectIon

for desIgnated cIrcuIts

example of use:l 40A electric showerl 6A first floor lightingl 6A ground floor lighting

maIn swItch

for IsolatIon

rcd protectIng up to

8 outgoIng ways

rcBos IndIvIdually protectIng

outgoIng cIrcuIts

K5686S MAG 17ED1 x 80A 30mA RCD and 1 x 63A 30mA RCD, allowing 10 outgoing ways with up to 5 circuits

per RCD. This Consumer Unit allows for 2 unprotected, or 2 RCBO ways.

cIrcuIts dIvIded across

2 rcds

10 outgoIng ways

5 + 5 splIt as

standard

allows for 2

unprotected, or 2

rcBo ways

DiMEnSiOnSwiDth hEight DEpth378mm 230mm 110mm


Unprotected WaysThe example shown is K5686s MAG 17ED with unprotected ways. Depending on the position of

the U link, multiple unprotected ways are possible on the K5681S, K5683S and the K5684S.

all 17th edItIon

consumer unIts

have the facIlIty to

provIde unprotected

ways

Examples where this configuration would be useful may be a

16A radial circuit to a dedicated socket outlet marked fridge or

freezer, or circuits supplying smoke alarms or burglar alarms.

If these were unprotected circuits an installation method

complying with 522.6.6, methods i, ii, iii, and iv would need to

be undertaken (as explained earlier in this brochure).

Both BS 5839-6:2004 and Part B of the Building Regulations

for England & Wales have requirements of power supplies

for dedicated circuits for smoke alarms. These should not be

connected to RCDs unless electrical safety dictates, and then

should not be connected to a device that protects socket

outlets. With the changes in the 17th Edition RCD protection

would be required if the cables were unprotected and at a

depth of less than 50mm, in this instance an RCBO would be

the ideal solution.


K5666S MAG 17ED2 x 63A 30mA RCDs, allowing 10 outgoing ways with up to 5 circuits per RCD. This Consumer

Unit allows for 2 unprotected, or 2 RCBO ways.


2 rcds

10 outgoIng ways

5 + 5 splIt as

standard

allows for 2

unprotected, or 2

rcBo ways



K5681S MAG 17ED1 x 80A 30mA RCD, 1 x 63A 30mA RCDs, allowing 15 outgoing ways. Multiple protected and

unprotected configurations are possible.

15 outgoIng ways

multIple protected

and unprotected

confIguratIons

cIrcuIts dIvIded across 2 rcds


K5683S MAG 17ED2 x 63A 30mA RCDs, allowing 15 outgoing ways. Multiple protected and unprotected

configurations are possible.

15 outgoIng ways

multIple protected

and unprotected

confIguratIons

cIrcuIts dIvIded across 2 rcds



K5684S MAG 17ED2 x 63A 30mA RCDs, 1 x 40A 30mA RCD, allowing 13 outgoing ways with 5 circuits, 5 circuits

and 3 circuits split as standard. Unprotected ways are possible with this Consumer Unit.

15 outgoIng ways

5 + 5 + 3 splIt as

standard

unprotected ways

possIBle


3 rcds


MK Sentry MCBs, RCBOs & RCDs

As shown, within the MK Sentry range a number of split load configurations are available

which meet the requirements of the 17th Edition. An essential element of the regulations is

the minimised hazard and inconvenience, and as such more than one RCD or RCBO per board

will be required. The following overview shows the total number of ways available with each

board, and the maximum number of circuits for each RCD.

For maximum flexibility, unpopulated boards can also be used in conjunction with MK RCDs,

RCBOs, MCBs and Switch Disconnectors to provide 17th Edition solutions.

17th EDitiOn – MK SEntRY Split lOAD COnSuMER unit COnFiguRAtiOninSulAtED BOARD liSt nO. MEtAl BOARD liSt nO. DESCRiptiOn tOtAl wAYS unpROtECtED RCD1 RCD2 RCD3K5666S MAG 17ED K5566S MAG 17ED 10 WAY 100A SWITCH,

2 X 63A 30mA RCD10 2 5 5 N/A

K5686S MAG 17ED K5586S MAG 17ED 10 WAY 100A SWITCH, 80A 30mA & 63A 30mA RCD

10 2 5 5 N/A

K5681S MAG 17ED K5581S MAG 17ED 15 WAY 100A SWITCH, 80A 30mA & 63A 30mA RCD

15 UP TO 9 UP TO 11 UP TO 8 N/A

K5683S MAG 17ED K5583S MAG 17ED 15 WAY 100A SWITCH, 2 X 63A 30mA RCD

15 UP TO 9 UP TO 11 UP TO 8 N/A

K5684S MAG 17ED K5584S MAG 17ED 13 WAY 100A SWITCH, 2 X 63A 30mA & 40A 30mA RCD

13 2 5 5 3

For the full range of MK Sentry Consumer Units refer to the main MK CatalogueNote: Installing Unprotected Ways subtracts from the available RCD Protected Ways

17th EDitiOn – MK SEntRY COnSuMER unitSinSulAtED BOARD liSt nO.

MEtAl SuRFACE MOuntED BOARD liSt nO.

MEtAl FluSh MOuntED BOARD liSt nO.

DESCRiptiOn tOtAl wAYS

K5612S K5512S K6512S ACCEPTS 12 ONE MODULE PRODUCTS (2 INTEGRAL NEUTRAL BARS FITTED WITH LINK) 12K5616S K5516S K6516S ACCEPTS 16 ONE MODULE PRODUCTS (3 INTEGRAL NEUTRAL BARS - LINKS SUPPLIED) 16K5621S K5521S K6521S ACCEPTS 21 ONE MODULE PRODUCTS (4 INTEGRAL NEUTRAL BARS – LINKS SUPPLIED) 21A Split Load Consumer Unit Cable Kit (K5564S) will be required for assembling a Switch and twin RCD arrangement For the full range of MK Sentry Consumer Units refer to the main MK Catalogue

MK Sentry RCBOs MK Sentry RCBOs (Residual Current Breakers with Overcurrent Protection) are of the solid neutral type,

single pole, in one module format. The RCBOs are a combination of a Type B MCB and a 30mA RCD. This

enables both overcurrent protection and earth fault current protection to be provided by a single unit.

This combination allows earth fault protection to be restricted to a single circuit, thus ensuring that only

the circuit with the fault is interrupted.

The operating dolly on all MK Sentry RCBOs may be locked in either the ON or OFF position without

affecting the ability of the trip mechanism to operate.

MK SEntRY RCBOSliSt nO. DESCRiptiOn CuRREnt RAting tRipping CuRREnt6932s RCBO WITH SOLID NEUTRAL TYPE B 6A 30mA6933s RCBO WITH SOLID NEUTRAL TYPE B 10A 30mA6934s RCBO WITH SOLID NEUTRAL TYPE B 16A 30mA6935s RCBO WITH SOLID NEUTRAL TYPE B 20A 30mA6936s RCBO WITH SOLID NEUTRAL TYPE B 32A 30mA6937s RCBO WITH SOLID NEUTRAL TYPE B 40A 30mA6938s RCBO WITH SOLID NEUTRAL TYPE B 45A 30mA6939s RCBO WITH SOLID NEUTRAL TYPE B 50A 30mAFor the full range of MK Sentry RCBOs refer to the main MK Catalogue.

MK Sentry MCBsMK Sentry MCBs (Miniature Circuit Breakers) are of the thermo-magnetic, current limiting type and are

available with either Type B or Type C operating characteristics. For the purpose of this brochure we have

only listed the Type B devices, the full range can be found in the MK Catalogue.

The operating dolly may be locked in either the ON or OFF position without affecting the ability of the

trip mechanism to operate. The contacts themselves are manufactured from carefully chosen materials,

selected specifically for their low electrical resistance and low propensity to weld under fault conditions.

When the green indicator is visible, a contact gap of 4mm has been achieved, therefore Sentry MCBs may

be used as a single pole isolating switch where appropriate. The Sentry MCB has a mid-trip fault indicator.

If there is a short circuit or current overload, the dolly moves to the mid-position to indicate a fault.

MK SEntRY MCBSliSt nO. DESCRiptiOn CuRREnt RAting5903s MCB Single Pole Type B 3A5906s MCB Single Pole Type B 6A5910s MCB Single Pole Type B 10A5916s MCB Single Pole Type B 16A5920s MCB Single Pole Type B 20A5932s MCB Single Pole Type B 32A5940s MCB Single Pole Type B 40A5945s MCB Single Pole Type B 45A5950s MCB Single Pole Type B 50AFor the full range of MK Sentry MCBs refer to the main MK Catalogue.


MK Sentry RCDs The MK Sentry range of RCDs (Residual Current Devices) offer a comprehensive

selection of devices designed to meet most residential, commercial and light

industrial requirements. The range includes two and four pole, a.c., d.c. fault

current sensitive and time delayed models, and a selection of current ratings from

16A to 100A, in a variety of tripping sensitivities. For the purpose of this brochure

we have only listed the 30mA 230V devices, the full range can be found in the MK

Catalogue.

When in the OFF position a contact gap of 4mm is present, enabling Sentry RCDs

to be used as isolating switches where appropriate. When the green indicator is

visible, a contact gap of 4mm has been achieved.

The operating dolly may be locked in either the ON or the OFF position without

affecting the ability of the trip mechanism to operate, ie the RCD is ‘trip-free’. It is

not possible to hold the contacts closed when a fault condition exists.

All MK Sentry RCDs incorporate a filtering device to provide protection against

transient surges in the supply to the unit, thus reducing the occurrence of

unwanted tripping.

MK SEntRY RCDS with 30MA tRipping CuRREntliSt nO. DESCRiptiOn CuRREnt RAting tRipping CuRREnt5716s RCD DOUBLE POLE 230V TWO MODULE 16A 30mA6730s RCD DOUBLE POLE 230V TWO MODULE 32A 30mA5740s RCD DOUBLE POLE 230V TWO MODULE 40A 30mA5760s RCD DOUBLE POLE 230V TWO MODULE 63A 30mA5780s RCD DOUBLE POLE 230V TWO MODULE 80A 30mA7700s RCD DOUBLE POLE 230V TWO MODULE 100A 30mA6716s RCD PULSATING D.C. FAULT CURRENT SENSITIVE DOUBLE POLE 230V TWO MODULE 16A 30mA6630s RCD PULSATING D.C. FAULT CURRENT SENSITIVE DOUBLE POLE 230V TWO MODULE 32A 30mA5640s RCD PULSATING D.C. FAULT CURRENT SENSITIVE DOUBLE POLE 230V TWO MODULE 40A 30mA5660s RCD PULSATING D.C. FAULT CURRENT SENSITIVE DOUBLE POLE 230V TWO MODULE 63A 30mAFor the full range of MK Sentry RCDs refer to the main MK Catalogue.


Glossary of terms

To interpret the new regulations, it is necessary to understand the terminology used. Electrical

Contractors should familiarise themselves with the following terms. A complete glossary is published

at the end of the 17th Edition document, here we have highlighted those which are particularly

relevant to the content of this brochure.

Competent personAn individual who posses sufficient technical knowledge and

experience for the nature of the electrical work undertaken and

is able at all times to prevent danger, and where appropriate,

injury to themselves or others.

Ordinary personAn individual who is neither skilled or instructed, for example a

home owner or building user.

Skilled personAn individual with technical knowledge or experience enabling

him/her to avoid dangers which may occur when using electricity,

for example a qualified electrician.

instructed personAn individual who has been adequately advised or supervised

to enable him/her to avoid the danger which may occur when

using electricity.

Basic protectionProtection against electric shock under fault-free conditions.

Note: For low voltage installations, systems and equipment, basic

protection generally corresponds to protection against direct

contact, that is ‘contact of persons or livestock with live parts’.

Fault protectionProtection against electric shock under single-fault conditions.

Note: For low voltage installations, systems and equipment,

fault protection generally corresponds to protection against

indirect contact, mainly with regard to failure of basic insulation.

Indirect contact is ‘contact of persons or livestock with

exposed-conductive-parts which have become live under fault

conditions’.

Safe ZoneRegulation 522.6.6 refers to a cable installed in a wall or partition

at a depth of less than 50mm from the surface. Method (v)

refers to the Safe Zone which is the area within 150mm from

the top of the wall or partition, or within 150mm of an angle

formed by two adjoining walls or partitions. Where the cable is

connected to a point, accessory or switchgear on any surface of

the wall or partition, the cable may be installed in a zone either

horizontally or vertically, to the point, accessory or switchgear.

Where the location of the accessory, point or switchgear can be

determined from the reverse side, a zone formed on one side

of a wall if 100mm thickness or less, or partition of 100mm

thickness or less, extends to the reverse side.

17th Edition Find out more

To find out more about the 17th Edition of the IEE Wiring Regulations, and the MK product solutions

including the MK Sentry range of Consumer Units, you can attend the MK CPD ‘Socket in a Shower – what’s that all about’, or listen to the MK Podcast, produced in association with the NICEIC and

Professional Electrician & Installer Magazine.

This CPD is aimed at Electrical Contractors, Specifiers

and Consultants, and is a review of the main changes to

BS 7671:2008 – the 17th Edition of the Wiring Regulations and

the impact upon the electrical industry.

For more information on this CPD and to register your interest

please visit www.switchonmk.com...

Socket in a Shower – What’s that all about?

Continuing Professional Development through the MK CPD Technical Seminar Programme

MK CPD Technical Seminar Programme

M a r k e t i n g D e p a r t m e n t T h e A r n o l d C e n t r e P a y c o c k e R o a d B a s i l d o n E s s e x S S14 3 E A U n i t e d K i n g d o m

Tel +44 (0)1268 563000 Website www.mkelec tr ic.co.uk / www.ackermann.co.uk E-mail [email protected]

Fax +44 (0)1268 563483 Registered Office: Honeywell House, Ar l ington Business Park , Bracknel l, Berk shire, RG12 1EB Registered No. 189291

Duration: 1 hour

Who should attend: Electrical Contractors, Specifiers & Consultants

January 2008 will see the publication of BS 7671, Requirements for Electrical Installations, 17th Edition of the IEE Wiring Regulations. This seminar takes a look at the main changes from the 16th to the 17th Edition, the reasons why and their impact.

CONTENT

Reasons for change

Structure

Numbering

Major changes chronologically for Parts 1-7 including;

Defi nitions

Protection against electric shock

Cables in walls

Bath & shower rooms

TITLEBRAND REPRESENTED

DESCRIPTIONEXTERNAL APPROVAL

Socket in a Shower – What’s that all about?

MK A review of the main changes to BS 7671:2008 – 17th Edition of the IEE Wiring Regulations and the impact upon the electrical world.

Construction CPDService

Whilst every effort has been made to ensure the information in this brochure is correct, British Standards and the IEE Wiring Regulations may be subject to change. This MK Electric brochure to 17th

Edition - MK Sentry Solutions is not a substitute to the ‘Requirements for Electrical Installations – IEE Wiring Regulations Seventeenth Edition’.

MK Electric has joined forces with the NICEIC and Professional

Electrician & Installer Magazine to produce a ground-breaking

initiative, the Electrical Industry’s first Podcast. Switch On MK

is an easy-listen, readily digestible podcast ‘radio show’ that

provides an excellent overview of the 17th Edition. It can be

heard over the Internet – at www.switchonmk.com – where

you can also download it to your computer or MP3 player. It can

also be found in the free, educational area of iTunes.

Led by technical journalist and broadcaster Roger Bisby, it

features Gary Gundry, Senior Engineer, and Paul Lawrence, Head

of Business, with the NICEIC; Simon Clarke, Training Manager of

MK Electric and Professional Electrician & Installer Magazine

Editor, Jonathan Cole.

mK electric

The Arno ld Cent re Paycocke Road Bas i ldon E s sex S S14 3EA Un i ted K ingdom technical helpline tel 01268 563720

Customer Service tel 01268 563404 literature helpline tel 0870 240 3385 E-mail [email protected]

Customer Service Fax 01268 563405 literature helpline Fax 0870 240 3386 website www.mkelectric.co.uk

Registered Office: Honeywell House Arlington Business Park Bracknell Berkshire RG12 1EB Registered no. 189291 Ref: MK242

TM

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