bs7671 2008: c&g 2382 outcomes 5 - legh...

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BS7671 2008: C&G 2382 Outcomes 5BS7671 2008: C&G 2382 Outcomes 5

•• Selection and erection of equipmentSelection and erection of equipment•• The candidate will be able to: The candidate will be able to:

•• 5.1 Identify the need for compliance with British Standards, or 5.1 Identify the need for compliance with British Standards, or harmonised harmonised European Standards and Codes of Practice. European Standards and Codes of Practice.

•• 5.2 State the effects that operational conditions and external i5.2 State the effects that operational conditions and external influences have nfluences have on the choice of installation methods, materials and equipment. on the choice of installation methods, materials and equipment.

•• 5.3 State the requirements for accessibility to equipment and co5.3 State the requirements for accessibility to equipment and connections nnections

•• 5.4 Describe the need for, and the 5.4 Describe the need for, and the sitingsiting and wording requirements of, circuit and wording requirements of, circuit charts, warning notices and labels. charts, warning notices and labels.

•• 5.5 State identification requirements for live and protective co5.5 State identification requirements for live and protective conductors. nductors.

•• 5.6 Describe the need to protect against mutual detrimental infl5.6 Describe the need to protect against mutual detrimental influences. uences.

•• 5.7 State the effect of each of the following on the selection a5.7 State the effect of each of the following on the selection and erection of nd erection of wiring systems wiring systems

•• a types of wiring system a types of wiring system •• b external influences b external influences •• c electrical connections c electrical connections •• d minimising the spread of fire d minimising the spread of fire •• e proximity of other services e proximity of other services •• f maintainability.f maintainability.

Selection and Erection compliance with standards

Compliance with standards: 511.1• Every item of equipment shall comply with 1. current editions or agreed amendment dates of its:2. British standard3. Harmonized standard• Compliance with a foreign standard based on IEC

standards as long as the degree of safety is equivalent to BS .

Or• Not covered by a BS, EN or HD then designer or

person responsible for specification must establish that the same degree of safety as afforded by the regulations (511.2)

• In each case above it must be recorded in any certification from BS7671 part 6

October 15 Legh Richardson

Compatibility512.1.5All equipment must conform to EMC

directive 2004/108Responsible persons to electromagetic

compatibility regs 2006Must ensure that all equipment is

compatible see 444

Harmonization with EuropeHarmonization with Europe514 Single and Three phase connections

Table 51 and Appendix 7

Harmonization with European StandardsHarmonization with European Standards

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514.9 Diagrams and documentation

514.9.1 A legible diagram, chart or table or equivalent form of information shall be provided indicating in particular:

(i) the type and composition of each circuit (points of utilisation served, number and size of conductors, type of wiring), and

(ii) the method used for compliance with Regulation 410.3.2, and (iii) the information necessary for the identification of each device

performing the functions of protection, isolation and switching,and its location, and

(iv) any circuit or equipment vulnerable to a typical test. For simple installations the foregoing information may be given in a

schedule. A durable copy of the schedule relating to a distribution board shall be provided within or adjacent to each distribution board.

Selection and Erection: Labels and NoticesSelection and Erection: Labels and Notices

514 Identification Labels 514 Identification Labels –– Dual Supplies and nonDual Supplies and non--standard coloursstandard colours

Warning – Dual SupplyIsolate both mains and on-site generation before carrying out work

Isolate the mains supply at …………………………………………

Isolate the generator at …………………………………………….

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Selection and erection Selection and erection ––part 5part 5

514 Identification 514 Identification -- labelslabels

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Selection and erection Selection and erection –– part 5part 5

514 Identification 514 Identification –– labels labels -- Installation of Installation of RCDsRCDs

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Selection and erection Selection and erection –– part 5part 5

514 Identification 514 Identification –– labels labels –– Earth Free Earth Free equipotentialequipotential BondingBonding


522. Cable trunking systems521.201 prefabricated systems including521.4 Busbar systems, powertrack521.10.1 containments to IPXXD or IP4X

521.11.201 containments in escape routes to be non-flame propagating

Cable runs adequately supported

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Selection and Erection Selection and Erection –– Part 5Part 5

522. Effects of External Influences 522. Effects of External Influences -- heatheat•• Protection of wiring systems byProtection of wiring systems by

1.1. ShieldingShielding2.2. DistanceDistance3.3. Type of wiringType of wiring4.4. Changing or reinforcing type of insulationChanging or reinforcing type of insulation

•• 522.2.201 extra insulation 522.2.201 extra insulation –– lighting, water heaterslighting, water heaters•• 522.3 IP rating for ingress of water522.3 IP rating for ingress of water•• 522.4 IP rating for ingress of dust and particles522.4 IP rating for ingress of dust and particles•• 522.5 corrosion from liquids, electrolytic action 522.5 corrosion from liquids, electrolytic action

from dissimilar metalsfrom dissimilar metals

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Selection and Erection Selection and Erection –– Part 5Part 5522.6 External Influences 522.6 External Influences –– impactimpact

•• 522.6.201 cables under floors and in ceilings522.6.201 cables under floors and in ceilings1.1. > 50 mm from top and bottom of joist> 50 mm from top and bottom of joist2.2. Protective earthed metal covering, Protective earthed metal covering, 3.3. enclosed in earthed metal conduit or enclosed in earthed metal conduit or trunkingtrunking4.4. Protection from penetrationProtection from penetration

•• 522.6.202 cables concealed in walls or partitions522.6.202 cables concealed in walls or partitions1.1. As 522.6.5 (i) As 522.6.5 (i) –– (iv)(iv)2.2. (v) Installed in safe zones (150 mm from the (v) Installed in safe zones (150 mm from the

edge of wall or ceiling, running vertically or edge of wall or ceiling, running vertically or horizontally to a accessible accessory)horizontally to a accessible accessory)


Mechanical protection and Impact522.6.203 Additional earthed metallic protection 522.6.203 Additional earthed metallic protection

required for cables buried in metal constructed walls required for cables buried in metal constructed walls and partitions or the use of 30mA and partitions or the use of 30mA RCDsRCDs to protect to protect those circuitsthose circuits

522.6.204 cables not protected by 522.6.204 cables not protected by RCDsRCDs to 415.1.1 must to 415.1.1 must bebe

1. incorporate earthed metallic covering1. incorporate earthed metallic covering2. earthed conduit2. earthed conduit3. earthed 3. earthed trunkingtrunking or ductingor ducting4. mechanical protection against nails and 4. mechanical protection against nails and

screwsscrews5. form part of a SELV or PELV to 414.45. form part of a SELV or PELV to 414.4

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Selection and Erection Selection and Erection –– Part 5Part 5522.8 External Influences 522.8 External Influences –– enclosed cablesenclosed cables•• 522.8.1 Protection for cable during erection, maintenance and us522.8.1 Protection for cable during erection, maintenance and usee•• 522.8.2 Cable enclosures to be fully erected before cables are d522.8.2 Cable enclosures to be fully erected before cables are drawn inrawn in•• 522.8.3 Cable radii do not stress conductors or terminations522.8.3 Cable radii do not stress conductors or terminations•• 522.8.4522.8.4--5 Cables supported at predetermined intervals so that no stress 5 Cables supported at predetermined intervals so that no stress

is applied to termination, cable, conductorsis applied to termination, cable, conductors•• 522.8.6 Space factor for drawing in cables522.8.6 Space factor for drawing in cables•• 522.8.10 buried cables must either have earthed metallic shield/522.8.10 buried cables must either have earthed metallic shield/armour armour

or suitable conduit pipe work protectionor suitable conduit pipe work protection•• Be at appropriate depth, have identification markings above themBe at appropriate depth, have identification markings above them, (IEC , (IEC

61386)61386)•• 522.8.11/12 cable supports must not have sharp edges or be damag522.8.11/12 cable supports must not have sharp edges or be damaged by ed by

them when erectedthem when erected•• 522.8.13 expansion couplers must not cause damage to cables522.8.13 expansion couplers must not cause damage to cables•• 522.8.14 load bearing structures must not be penetrated by cable522.8.14 load bearing structures must not be penetrated by cabless

All external influences are given greater classification in AppeAll external influences are given greater classification in Appendix 5ndix 5

Selection and Erection Part 5Selection and Erection Part 5External Influences External Influences -- impactimpact

> 50mm

> 50mm

The Neutral Zone

0.25 - 0.4max notch = 0.125*span, hole = 0.125 span max and *3 hole dia. separation

Selection and Erection Part 5Selection and Erection Part 5External Influences External Influences -- ImpactImpact

Protected by conduit to a depth of 50mm

Vertical Zone

Horizontal Zone

522.6.202 and 522.6.203 compliance with 415.1.1 30mA RCD protection

150mm

150mm

Permitted Cable routes

Accessory Safe Zones

Selection and Erection Selection and Erection -- Part 5Part 5

522.8 Buried cables522.8 Buried cables

Not less than 600mm

Earthed Armoured Cable

only

Soft Sand

Sifted Sand or other material

Back fill with top

soilNot less than

150mm

Back fill with rough soil

Warning Labels and /or identification tape

Rule of Thumb correction factor for Buried cables is 0.9

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Selection and Erection Selection and Erection –– Part 5Part 5526.1 Connections526.1 Connections•• Durable electrical continuityDurable electrical continuity•• Adequate strengthAdequate strength•• ProtectionProtection526.2 methods and selection of connections526.2 methods and selection of connections•• Conductor and insulator materialsConductor and insulator materials•• Number and shape of wires forming the conductorNumber and shape of wires forming the conductor•• CsaCsa of conductorof conductor•• Number of conductors connected togetherNumber of conductors connected together•• Temperature of joint for normal operationTemperature of joint for normal operation•• Prevent mechanical movement under vibrationPrevent mechanical movement under vibration

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Selection and Erection Selection and Erection –– part 5part 5

526.3 Accessibility526.3 AccessibilityEvery connection shall be accessible for inspectionEvery connection shall be accessible for inspection•• Exceptions include:Exceptions include:1.1. Designed to be buriedDesigned to be buried2.2. Compound resin jointCompound resin joint3.3. Connection to floor/ceiling heating elementsConnection to floor/ceiling heating elements4.4. Soldered, welded, brazed, compressed jointsSoldered, welded, brazed, compressed joints

526.6/7/8 Mechanical strain and enclosure of stripped 526.6/7/8 Mechanical strain and enclosure of stripped back sheathing and armour protected by terminal back sheathing and armour protected by terminal enclosuresenclosures

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Selection and Erection Selection and Erection –– part 5part 5

526.9 Multi stranded conductors526.9 Multi stranded conductors•• 526.9.1 To reduce the separation of fine conductor 526.9.1 To reduce the separation of fine conductor

wires suitable terminals shall be usedwires suitable terminals shall be used•• 526.9.2 Soldering or tinning is not permitted when 526.9.2 Soldering or tinning is not permitted when

using screw terminalsusing screw terminals•• 526.9.3 As above but applicable to movement at the 526.9.3 As above but applicable to movement at the

jointjoint

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BS7671 2008: C&G 2382 Outcomes 5 continuedBS7671 2008: C&G 2382 Outcomes 5 continued

•• 5.8 Use the following to determine conductor size and select app5.8 Use the following to determine conductor size and select appropriate ropriate cable from Appendix 4 cable from Appendix 4 •• a design current a design current •• b b overcurrentovercurrent protection protection •• c cable route c cable route •• d correction factors d correction factors •• e voltage drop limitations e voltage drop limitations •• f diversity. f diversity.

•• 5.9 State the difference between, and the requirements for 5.9 State the difference between, and the requirements for •• a isolation a isolation

•• b switching off for mechanical maintenance b switching off for mechanical maintenance •• c emergency switching d functional switching c emergency switching d functional switching

•• 5.10 State the uses of monitoring 5.10 State the uses of monitoring •• a insulation a insulation •• b residual current b residual current

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Installation Circuit Arrangements Installation Circuit Arrangements -- Part 3 and Part 3 and Part 5Part 5

The number of circuits and outlets per distribution board will bThe number of circuits and outlets per distribution board will be e dependent upon purpose: dependent upon purpose:

520.3 Consideration given to application of Fundamental principl520.3 Consideration given to application of Fundamental principles es (13) as it applies to:(13) as it applies to:1.1. Cables and conductorsCables and conductors2.2. Connections, terminations and jointsConnections, terminations and joints3.3. Supports and suspensionsSupports and suspensions4.4. Enclosures and protection against external influencesEnclosures and protection against external influences

OvercurrentOvercurrent protection protection -- Chapter 43Chapter 43Isolation and Switching Isolation and Switching -- Section 537Section 537Current carrying capacity of the conductors Current carrying capacity of the conductors –– Section 523Section 523External Influences External Influences –– Chapter 52, 522, App 5Chapter 52, 522, App 5

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Cable Selection overviewCable Selection overview

The requirements are:The requirements are:•• The cable supplying the load should be able to carry the currentThe cable supplying the load should be able to carry the current

to the load safely, after taking into account diversity, withoutto the load safely, after taking into account diversity, withoutthe cable overheating (523, app 4)the cable overheating (523, app 4)

•• Protective devices should be able to provide protection for the Protective devices should be able to provide protection for the cable from excess current (432,433)cable from excess current (432,433)

•• The length of the cable is limited to ensure adequate voltage The length of the cable is limited to ensure adequate voltage supplies the load (525)supplies the load (525)

•• Maximum loop impedance of a circuit is low enough to ensure Maximum loop impedance of a circuit is low enough to ensure disconnection within times specified by Table 41.1disconnection within times specified by Table 41.1

•• 0.4 (TN) and 0.2sec (TT) for all circuits <32A0.4 (TN) and 0.2sec (TT) for all circuits <32A•• 5 sec disconnection time for Sub5 sec disconnection time for Sub--mains distribution circuits and > mains distribution circuits and >

32A (under the supervision of trained personnel)32A (under the supervision of trained personnel)

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BS7671 2008: DesignBS7671 2008: Design•• The rules for circuit design have not changed The rules for circuit design have not changed

dramaticallydramatically

•• MCBsMCBs and and MCCBsMCCBs will disconnect a short Circuit fault will disconnect a short Circuit fault within 0.1s (0.01s)within 0.1s (0.01s)

•• Most of the new rules apply directly to domestic Most of the new rules apply directly to domestic installationsinstallations

•• Industrial and Commercial Installations where trained Industrial and Commercial Installations where trained and supervised personnel have control, other methods and supervised personnel have control, other methods of protection may still be used (Local Supplementary of protection may still be used (Local Supplementary Earthed Earthed EquipotentialEquipotential Bonding, nonBonding, non--conducting conducting locations earthlocations earth--free free equipotentialequipotential bonding)bonding)

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Main elements of circuit Design for conventional Main elements of circuit Design for conventional CircuitsCircuits

•• 1 1 -- Determine Design Current Determine Design Current -- actual flow of current actual flow of current through the cables (through the cables (IbIb) less diversity where ) less diversity where appropriateappropriate

•• 2 2 -- Select type and size of protective device (In)Select type and size of protective device (In)•• 3 3 -- Apply any correction factors to reduce self Apply any correction factors to reduce self

heating of cables (It)heating of cables (It)•• 4 4 -- Select type and size of cable from Appendix 4 Select type and size of cable from Appendix 4

((IzIz))•• 5 5 -- Determine whether volt drop is satisfactory for Determine whether volt drop is satisfactory for

length, loading and routing of cableslength, loading and routing of cables•• Note: In most practical applications where an Note: In most practical applications where an

installation already exists you may not have the installation already exists you may not have the choice of type but only sizechoice of type but only size

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Applying Electrical Design: Cable SizingApplying Electrical Design: Cable Sizing

•• Load Current (I) and Design Current (Load Current (I) and Design Current (IbIb))•• Effective continuous current flow through a circuitEffective continuous current flow through a circuit•• Basic Calculation Basic Calculation

•• When calculating Design current with inductive loading When calculating Design current with inductive loading and where there is insufficient information available and where there is insufficient information available apply a factor of 1.8 to the power consumption apply a factor of 1.8 to the power consumption -- *App 1 *App 1 Table 1A OSG note 2*Table 1A OSG note 2*

•• Alternatively, If the power factor is known then apply:Alternatively, If the power factor is known then apply:

P=V . I or I= PV

I= P×1 .8V

P=V ×I×Cosθ or P=√3×V L×I L×Cosθ

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Design Current (IDesign Current (IBB))•• Maximum Demand 311.1Maximum Demand 311.1

•• Diversity may be taken into account when determining Diversity may be taken into account when determining Maximum demand Maximum demand

•• Diversity Diversity –– OSG Appendix 1 table 1a,b and cOSG Appendix 1 table 1a,b and c•• Not all circuits run at their full power rating, Not all circuits run at their full power rating,

•• Cooker circuitsCooker circuits•• Minus First 10A then 30% of the rest add 10A to the total + 5A fMinus First 10A then 30% of the rest add 10A to the total + 5A for or sktskt

outletsoutlets•• Lighting circuitsLighting circuits

•• Domestic lighting 66% is assumed to be on continuouslyDomestic lighting 66% is assumed to be on continuously

•• Power CircuitsPower Circuits•• 11stst circuit = Full Rating; 2circuit = Full Rating; 2ndnd circuit 40% and all other circuitscircuit 40% and all other circuits

•• Diversity applies to groups of circuits or/and Cables supplying Diversity applies to groups of circuits or/and Cables supplying groups of circuits such as a subgroups of circuits such as a sub--mains distribution boardsmains distribution boards

Applying Electrical Design: Cable SizingApplying Electrical Design: Cable Sizing524.1 csa’s of conductors should not be less than the values given in

table 52.3, except for ELV lighting 559.11.5.2


CSA’s of conductors524.2.1 Neutral conductors the same as the line

conductors1. single phase 2-wire for any size2. Polyphase or single phase 3-wire circuits <16mm2 CU and 25mm2

AL3. Neutrals sized according to 523.6.3

524.2.3 polyphase circuits> 16mm2 Cu and 25mm2 Al neutrals can be sized smaller to:

1. Not greater than ccc expected in the neutral for normal service2. Monitoring of neutral and auto. disconnection of the lines

conductors3. Minimum sized neutral is = 16mm2 Cu or 25mm2 Al

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Applying Electrical Design: Cable SizingApplying Electrical Design: Cable SizingCorrection Factors Correction Factors --

Appendix 4 introduction, *Appendix 4, OSG Appendix 6*Appendix 4 introduction, *Appendix 4, OSG Appendix 6*

Ambient Temperature Ambient Temperature –– (C(Caa))Grouping of other circuits Grouping of other circuits –– (C(Cgg))The effects of Thermal Insulation The effects of Thermal Insulation –– ((CCii))BS3036 Overload factor BS3036 Overload factor –– (C(Ccc))1.45.Iz 1.45.Iz II22 If the fusing Factor is 2 max. then:If the fusing Factor is 2 max. then:

General formula to be applied: (includes factor for BS General formula to be applied: (includes factor for BS 3036 fuses)3036 fuses)

Multiplier of 1. 45 assumed to be satisfactory for overload protection

∴1. 452

=0. 725 Iz≥In0 . 725

CcCfCdCsCCCII

iga

nt

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Applying Electrical Design: Cable SizingApplying Electrical Design: Cable SizingThe general formula is one possible area where knowledge of The general formula is one possible area where knowledge of

electricity will reduce the cost of installationelectricity will reduce the cost of installationOnly the worst factor need to be used if there is no concurrencOnly the worst factor need to be used if there is no concurrency in y in

factors, Appendix 4: factors, Appendix 4: parapara. 5.1.1. 5.1.1

Cg Ca Ci

Non-concurrent factors

Cg Ca Ci

concurrent factors

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Applying Electrical Design: Cable SizingApplying Electrical Design: Cable SizingCorrection Factors for Grouping Appendix 4 Correction Factors for Grouping Appendix 4 parapara 2.3.3.12.3.3.1

•• Group factors applied from tables 4C1 Group factors applied from tables 4C1 –– 4C54C5

•• Groups of nonGroups of non--sheathed and sheathed cables enclosed and/or sheathed and sheathed cables enclosed and/or supported by supported by trunkingtrunking, tray etc. , tray etc.

For large groups It can be prohibitive. A reasonable estimate caFor large groups It can be prohibitive. A reasonable estimate can be n be assumed: assumed: -- 523.5 and *OSG Table 6C note 2*523.5 and *OSG Table 6C note 2*

•• A cable not exceeding 30% of its grouped cable rating can A cable not exceeding 30% of its grouped cable rating can be ignoredbe ignored

•• that is:that is:

•• Grouping Factor can be applied to N Grouping Factor can be applied to N -- M cables (N = total M cables (N = total number of grouped cablesnumber of grouped cables

I t≥InCg

Where M cables carry 0 .3×C g× I t

F=1√n

where F=Group rating factor , n=number of circuits

Correction FactorsCorrection Factors

Comparison of grouping factorsComparison of grouping factors

Number of circuits ‘n’

App 4. Table 4C1 row 1

4

9

F=1√n

Applying electrical designApplying electrical designMethods of InstallationMethods of InstallationMethod 16th ed 17th ed Ref.Thermal insulation on one side 4 A 523., App4D

In Conduit or Trunking 3 B App 4A2

Clipped direct 1 C App 4A2

Buried in the ground - D App 4A2

Cable tray / Free air 11/18 E/F App 4A2

Twin and earth clipped to outer joist < 100mm of thermal insulation

- 100 App 4 table 4A2, 4D5

Twin and earth clipped to outer joist > 100mm of thermal insulation

- 101 App 4 table 4A2

Twin and earth clipped to internal stud wall – exterior wall


Twin and earth clipped to internal stud wall or buried in thermal ins.


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•• Correction Factors for Ambient Temperature Correction Factors for Ambient Temperature -- Appendix 4Appendix 4

•• Table 4B1 Table 4B1 –– cables in free air applicable to <> 30cables in free air applicable to <> 30CC•• Table 4B2 Table 4B2 -- buried cables <> 20buried cables <> 20CC•• Para. 5.1.1: For Short Circuit and Overload protection Para. 5.1.1: For Short Circuit and Overload protection

protected by 433.1.4 and BS3036 fuses then applying the protected by 433.1.4 and BS3036 fuses then applying the following 0.9 factor or:following 0.9 factor or:

•• The worst possible case should be used The worst possible case should be used --

I t≥InCa

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•• Correction Factors for Thermal Insulation 523.7Correction Factors for Thermal Insulation 523.7

•• 1. Thermally insulated surface on one side of the cable1. Thermally insulated surface on one side of the cable•• Reference method A (appendix 4 tables)Reference method A (appendix 4 tables)•• 2. Single cable totally surrounded by thermal insulation over a 2. Single cable totally surrounded by thermal insulation over a

length greater than 0.5mlength greater than 0.5mDeDe--rate maximum current carrying capacity to rate maximum current carrying capacity to 0.5 times 0.5 times -- method C method C

(clipped direct)(clipped direct)

•• 3. Totally surrounded 3. Totally surrounded -- Less than 0.5m Less than 0.5m -- table 52.2table 52.2

I t≥InC i


Isolation and SwitchingProtection530.3 switch contacts open simultaneously, the neutral

may open last and close first.530.3.2 No neutral switching devices

530.3.5 Auto re-closing devices for switching, protection, control must not be used where there is no skilled overseer

Not used to fulfil 411.3.3, 415.1., 522.6.202 – 203 must check insualtion resistance before reclosing

Auto function cannot reset once manually switched offTime delay before first automatic reclosureNumber of automatic reclosures is limited (3 times?)

Legh Richardson 39

Isolation and SwitchingIsolation and Switching

53 Protection53 Protection•• 531 Devices for fault protection by automatic 531 Devices for fault protection by automatic

disconnection must comply with chapter 41disconnection must comply with chapter 41•• 532 Devices for protection against fire will 532 Devices for protection against fire will

comply with 422.3.9 and 531.2 (chapter 41)comply with 422.3.9 and 531.2 (chapter 41)1.1.RCD devices for fault protection 531.2RCD devices for fault protection 531.22.2.at the origin of installationat the origin of installation3.3.switches all live conductorsswitches all live conductors4.4.device rated at < 300mAdevice rated at < 300mA


Protection against overcurrent533.1.1: The use of fuses to BS3036, BS88-3, BS1362

• Insulated enclosure• Screw in fuses – centre to supply and casing connected to load

side (bottle fuses)• Identified on barrel or enclosure• No inter-changeability• Isolator switch on supply side for polyphase circuits


Overcurrent protection533.1.1 use of fuses: Table 53.1

0.7525

2.01000.620

1.8800.515

1.53600.3510

1.25450.25

0.85300.153

Nominal Diameter (mm)Current rating (In)Nominal diameter

(mm)Current rating (In)


Overcurrent protection533.2 harmonic currents to be considered

when designing for overload (I2)

533.3 and 536 circuit designs should take account of maximum breaking capacities, coordination, maximum and minimum fault currents


Protection against overvoltage

• 534.1 The use of SPDs

• Atmospheric, lightning on or near the installation

• Transient switching and supply faults


Protection against overvoltage534.2: Installed near the origin of

installationInstalled in the main switchgear

cabinets

• Type 1 – equipotential bonding SPD for fire and shock protection throughout the installation

• Type 2 – protection for origin and sensitive equipment

• Type 3 – sensitive equipment

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Isolation and SwitchingIsolation and Switching537.2.1 every circuit shall be isolated 537.2.1 every circuit shall be isolated

from the live supply from the live supply Three points of Isolation:Three points of Isolation:1.1. Origin (537.1.4)Origin (537.1.4)2.2. Distribution Boards (537.2.1.1)Distribution Boards (537.2.1.1)3.3. Final Circuits (537.2.1.1)Final Circuits (537.2.1.1)Must Isolate all phases but not Must Isolate all phases but not

necessarily the neutral necessarily the neutral –– no link in CPCno link in CPCNote: 537.2.1.7Note: 537.2.1.7Isolation at the originIsolation at the originTNTN--S = Phases or Phases and NeutralS = Phases or Phases and NeutralTNTN--CC--S = Phases only but both phases and S = Phases only but both phases and

Neutral where access is obtained by Neutral where access is obtained by unskilled persons (537.1.4)unskilled persons (537.1.4)

TT = Both Phase and NeutralTT = Both Phase and Neutral

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Isolation and SwitchingIsolation and SwitchingTable 53.4Tabulated BS and functionality (extract)

EN 50428

BS EN 50428

BS

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Isolation and SwitchingIsolation and Switching537.3 Switching for Mechanical Maintenance537.3 Switching for Mechanical Maintenance•• Must be able to interrupt the full load current 537.3.2.1Must be able to interrupt the full load current 537.3.2.1•• Methods of switching include:Methods of switching include:1.1. MultipoleMultipole switchswitch2.2. Circuit breakerCircuit breaker3.3. Control and protective switching device (CPS)Control and protective switching device (CPS)4.4. Control switch operating a contactorControl switch operating a contactor5.5. Plug and socket outletPlug and socket outlet

537.3.2.2 Manual operation537.3.2.2 Manual operation537.3.2.3prevent inadvertent switching on537.3.2.3prevent inadvertent switching on537.3.2.4 readily identifiable 537.3.2.4 readily identifiable 537.3.2.5 disconnect safely on537.3.2.5 disconnect safely on--loadload537.3.2.6 plug and socket suitable <16A537.3.2.6 plug and socket suitable <16A

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Isolation and SwitchingIsolation and Switching537.4.1 Emergency Switching537.4.1 Emergency Switching general rulesgeneral rules•• 537.4.2 Devices for emergency switching537.4.2 Devices for emergency switching1.1. Must break on full loadMust break on full load2.2. Via main switch or auxiliary controlVia main switch or auxiliary control3.3. Must be clearly labelled and fixed in a suitable placeMust be clearly labelled and fixed in a suitable place4.4. Hand operated devices preferred, Hand operated devices preferred, 5.5. Stop buttons must latch in the off position and not reStop buttons must latch in the off position and not re--energise energise

when releasedwhen released6.6. 537.4.2.8 Plugs and sockets are not suitable for emergency 537.4.2.8 Plugs and sockets are not suitable for emergency

switchingswitching

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Isolation and SwitchingIsolation and Switching537.5 Functional Switching537.5 Functional Switching1.1. Phase or all live conductors, Phase or all live conductors, 2.2. OnOn--load only, load only, 3.3. current control (semiconductor),current control (semiconductor),4.4. Not fuses or isolatorsNot fuses or isolators

537.5.4 Motor control537.5.4 Motor control1.1. NonNon--automatic restartautomatic restart2.2. NonNon--reversal of motor on breakingreversal of motor on breaking3.3. NonNon--reversal of motor for safety purposes reversal of motor for safety purposes

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Isolation and SwitchingIsolation and Switching

537.6 537.6 FirefighterFirefighter’’ss SwitchSwitch•• Applies to Interior HV discharge lightingApplies to Interior HV discharge lighting•• HV exterior InstallationsHV exterior Installations

•• Coloured RedColoured Red•• Positioned < 2.75m from groundPositioned < 2.75m from ground•• Off position = upwardOff position = upward

Legh Richardson 51

BS7671 2008: C&G 2382 Outcomes 5 continuedBS7671 2008: C&G 2382 Outcomes 5 continued•• 5.11 Identify types of devices offering protection against risk 5.11 Identify types of devices offering protection against risk of fire of fire

•• 5.12 Identify types of devices offering protection against 5.12 Identify types of devices offering protection against overcurrentovercurrent. .

•• 5.13 Describe 5.13 Describe earthingearthing arrangements to facilitate automatic disconnection of supply. arrangements to facilitate automatic disconnection of supply.

•• 5.14 State the recognised types of earth electrode and their app5.14 State the recognised types of earth electrode and their applications. lications.

•• 5.15 Determine, and select types and sizes of 5.15 Determine, and select types and sizes of •• a main protective bonding conductors a main protective bonding conductors •• b supplementary bonding conductors b supplementary bonding conductors •• c circuit protective conductors c circuit protective conductors •• d d earthingearthing conductors. conductors.

•• 5.16 Identify the requirements relevant to the installation of e5.16 Identify the requirements relevant to the installation of equipment having High quipment having High Protective Conductor Currents Protective Conductor Currents

•• 5.17 Describe the dangers in the use of equipment outside the 5.17 Describe the dangers in the use of equipment outside the equipotentialequipotential zone. zone.

•• 5.18 State how electric shock protection is provided by 5.18 State how electric shock protection is provided by •• a RCD protected socketa RCD protected socket--outlets/circuits outlets/circuits •• b the installation of an RCD in a TT system. b the installation of an RCD in a TT system.


Monitoring devices538.4 RCM for continual earth leakage currentsAlert of first fault or capacitive, leakage activityNot for shock protectionCan be installed upstream or down stream of other RCDs .

I f installed downstream the corresponding RCM should be <30% tripping current

Legh Richardson 53

EarthingEarthing Arrangements and protective conductorsArrangements and protective conductors

542.2.1 Earth Electrodes542.2.1 Earth Electrodes1.1. Earth rods and pipesEarth rods and pipes2.2. Earth tapes or wiresEarth tapes or wires3.3. Earth platesEarth plates4.4. Underground embedded structural steelworkUnderground embedded structural steelwork5.5. Welded metal reinforcement of concrete embedded in the Welded metal reinforcement of concrete embedded in the

earth (not preearth (not pre--stressed)stressed)6.6. Lead sheaths and other metal coveringsLead sheaths and other metal coverings

1.1. See 542.2.5 and 542.2.4See 542.2.5 and 542.2.47.7. Other suitable underground metalworkOther suitable underground metalwork

Legh Richardson 54

EarthingEarthing ArrangementsArrangements

EarthingEarthing and Protective Conductorsand Protective Conductors•• 1. Single core conductors 1. Single core conductors --543.2.2543.2.2•• 2. Conductor incorporated in a cable2. Conductor incorporated in a cable•• 3. Single core cable insulated bare in the same enclosure as the3. Single core cable insulated bare in the same enclosure as the

circuitcircuit•• 4. A fixed bare or insulated conductor4. A fixed bare or insulated conductor•• 5. sheathing, armour or screen surrounding live conductors5. sheathing, armour or screen surrounding live conductors•• 6. A metal conduit or 6. A metal conduit or trunkingtrunking –– not cable tray not cable tray –– must be an must be an

enclosureenclosure•• 7. Converting an extraneous conductive part 7. Converting an extraneous conductive part •• Flexible, Pliable conduits, service pipes are not Flexible, Pliable conduits, service pipes are not

acceptable acceptable –– 543.2.1543.2.1•• Up to 10mm2 protective conductors must be made of Up to 10mm2 protective conductors must be made of

copper copper –– 543.2.3543.2.3

55


Sizing of main and circuit Protective ConductorsSizing of main and circuit Protective Conductors

CrossCross--sectional area sectional area of phase conductor of phase conductor ‘‘ss’’ (mm(mm22))

Minimum crossMinimum cross--sectional area of the sectional area of the corresponding protective conductorcorresponding protective conductor

Protective conductor Protective conductor and phase conductor and phase conductor are of the same are of the same material material (mm(mm22))

The protective The protective conductor is made of a conductor is made of a different material to different material to the phase conductor the phase conductor (mm(mm22))

S S ≤≤ 1616 SS K1 / k2 x SK1 / k2 x S

16 16 < S < S ≤≤ 3535 1616 K1 / k2 x 16K1 / k2 x 16

S S > 35> 35 S / 2S / 2 K1 / k2 x S / 2K1 / k2 x S / 2

K1 = k value for Line conductor – Table 43.1K2 = k value for protective conductor – Tables 54.2 – 54.6

56


543.1 Sizing of Circuit Protective Conductors543.1 Sizing of Circuit Protective Conductors•• For individual circuits and circuits sharing a protective conducFor individual circuits and circuits sharing a protective conductortor•• (i) Calculated in accordance with 543.1.3(i) Calculated in accordance with 543.1.3

•• S = nominal crossS = nominal cross--sectional area of protective conductorsectional area of protective conductor•• I = I = rmsrms current in amps (due consideration to impedance of current in amps (due consideration to impedance of

circuit)circuit)•• t = operating time of the protective devicet = operating time of the protective device•• k = factor to adjust for temperature coefficient of resistance, k = factor to adjust for temperature coefficient of resistance,

resistivityresistivity, latent heat of material with regard to initial and final , latent heat of material with regard to initial and final temperaturestemperatures

•• (ii) Use table 54.7 where calculation is not required(ii) Use table 54.7 where calculation is not required•• Note standard circuit arrangements Note standard circuit arrangements –– OSG, BS6004 OSG, BS6004 –– cable cable

manufacturersmanufacturers

S=√I 2 tk

57

EarthingEarthing ArrangementsArrangementsEarthingEarthing arrangements (TT) with Main arrangements (TT) with Main ‘‘EquipotentialEquipotential’’ Bonding ZoneBonding Zone

•• Provides an environment where the voltage across exposed and Provides an environment where the voltage across exposed and extraneous metal work is the same.extraneous metal work is the same.

58


Sizing of main protective earth bonding ConductorsSizing of main protective earth bonding Conductors•• Main Earth Bonds Chapter 54, Section 544, Table Main Earth Bonds Chapter 54, Section 544, Table

54.854.8

•• TNTN--S and TT systemsS and TT systems•• ≥≥ ½½ main main earthingearthing conductorconductor•• ≤≤ 6mm2 minimum6mm2 minimum•• 25mm2 maximum25mm2 maximum

•• TNTN--CC--S Systems useS Systems use•• Table oppositeTable opposite

Copper equivalent Copper equivalent crosscross--sectional sectional areaofareaof the supply the supply neutral conductorneutral conductor

Minimum copper Minimum copper equivalent crossequivalent cross--sectional area of sectional area of main main equipotentialequipotentialbonding conductorbonding conductor

35mm2 or less35mm2 or less 10mm210mm2Over 35mm2 up to Over 35mm2 up to

50mm250mm216mm216mm2

Over 50mm2 up to Over 50mm2 up to 95mm295mm2

25mm225mm2

Over 95mm2 up to Over 95mm2 up to 150mm2150mm2

35mm235mm2

Over 150mm2Over 150mm2 50mm250mm2

59

EquipotentialEquipotential Bonding ConductorsBonding Conductors

Positioning of bonding connections Positioning of bonding connections –– 544.1.2544.1.2

Incoming Services

External supply meters are bonded at the point of entry

Cross Bond

≤ 600mm2

Gas

Water

EquipotentialBonding 10mm2

Continuous connection

60

EarthingEarthing ArrangementsArrangements•• Installations Protective ConductorsInstallations Protective Conductors•• 1/. Circuit Protective Conductors1/. Circuit Protective Conductors•• 2/. Main 2/. Main EquipotentialEquipotential Bonding Conductor Bonding Conductor •• 3/ Main 3/ Main EarthingEarthing ConductorConductor•• 4/. Supplementary Bonding Conductors4/. Supplementary Bonding Conductors•• B = Main B = Main EarthingEarthing TerminalTerminal•• E = main E = main earthingearthing ConductorConductor•• B = current using equipmentB = current using equipment•• C = Structural steelworkC = Structural steelwork•• P = Service piesP = Service pies

•• Protective Bonding must be applied Protective Bonding must be applied •• to all areas where there is:to all areas where there is:•• (i) exposed and extraneous metalwork(i) exposed and extraneous metalwork•• (ii) the likelihood of shock is greatly(ii) the likelihood of shock is greatly•• Increased to waterIncreased to water

M

B

M

M

P

C

T

E

1

1

1

2

2 2*

4

4

3

61

Definitions of Conductive Metalwork (part 2)Definitions of Conductive Metalwork (part 2)

Exposed Conductive Part:Exposed Conductive Part:•• Metallic enclosure associated with the electrical Metallic enclosure associated with the electrical

installation that could become live in the event of a installation that could become live in the event of a fault causing dangerfault causing danger

Extraneous Conductive Part:Extraneous Conductive Part:•• A metallic fixture not associated with the electrical A metallic fixture not associated with the electrical

installation that could become live under fault installation that could become live under fault conditions causing a difference in potential and conditions causing a difference in potential and dangerdanger


62


Supplementary Bonding Supplementary Bonding –– 544.2544.2•• Minimum size = 2.5mmMinimum size = 2.5mm22 with mechanical protectionwith mechanical protection•• Minimum size = 4.0mmMinimum size = 4.0mm22 without mechanical without mechanical

protectionprotection•• 1/ Exposed conductive part to exposed conductive part 1/ Exposed conductive part to exposed conductive part ––

544.2.1544.2.1•• Minimum size Minimum size ≥≥ to smallest protective conductorto smallest protective conductor

•• 2/ Extraneous conductive part to extraneous part 2/ Extraneous conductive part to extraneous part ––544.2.2544.2.2

•• 3/ Exposed conductive part to extraneous part 3/ Exposed conductive part to extraneous part –– 544.2.3544.2.3

•• Fixed appliances in bathrooms where a protective Fixed appliances in bathrooms where a protective conductor is incorporated within the flex need not have a conductor is incorporated within the flex need not have a separate supplementary bonding wire attached separate supplementary bonding wire attached –– 544.2.5544.2.5

63

544.1 PME Supply to Installation544.1 PME Supply to Installation•• (TN(TN--CC--S)S)

Consumer Unit or Distribution Board

Shared Main Earthing Terminal

Main EquipotentialBonding Conductors

Same Size EarthingConductor


64

Previously before 16Previously before 16thth 2001 the 2001 the earthingearthing conductor conductor may have been quite small as long it satisfied section may have been quite small as long it satisfied section 543.1 (543.1 (csacsa of protective conductors)of protective conductors)

•• The The earthingearthing conductor must now also satisfy conductor must now also satisfy regulation 543.1.4 and 544.1regulation 543.1.4 and 544.1

Example of sizing Example of sizing EarthingEarthing ConductorsConductors•• A PME service to an installation has a supply A PME service to an installation has a supply

neutral conductor of 70mmneutral conductor of 70mm22 copper. From the copper. From the tables 54.7 and 54.8, the tables 54.7 and 54.8, the earthingearthing conductor and conductor and the main bonding conductors must be at least the main bonding conductors must be at least ________ mm________ mm22 and __________ mmand __________ mm22 copper or copper or equivalent, respectively equivalent, respectively


65

EarthingEarthing requirements with high conductor currentsrequirements with high conductor currents•• < 3.5mA treat as an ordinary circuit< 3.5mA treat as an ordinary circuit•• 543.7.1.201 Protective conductor currents >3.5mA 543.7.1.201 Protective conductor currents >3.5mA

<10mA<10mA1.1. Permanently connected equipmentPermanently connected equipment2.2. Via Plug and Socket to BS EN 60309Via Plug and Socket to BS EN 60309--22•• 543.7.1.202 Protective conductor currents >10mA543.7.1.202 Protective conductor currents >10mA1.1. Permanently connected equipment with either:Permanently connected equipment with either:

1.1. 10mm2 unprotected or 4mm2 protected 10mm2 unprotected or 4mm2 protected cpccpc2.2. Two individual conductors, such as conduit and Two individual conductors, such as conduit and cpccpc, , swaswa and and

insulated conductor coreinsulated conductor core3.3. Earth monitoring Earth monitoring sysemsysem

2.2. Flexible cable via BS EN 60309 plug and socket >2.5mm2 Flexible cable via BS EN 60309 plug and socket >2.5mm2 cpccpc<16A and >4mm2 >16A<16A and >4mm2 >16A

3.3. Earth Monitoring system complying to BS 4444 with automatic Earth Monitoring system complying to BS 4444 with automatic

disconnect on faultdisconnect on fault..

EarthingEarthing High Protective Conductor CurrentsHigh Protective Conductor Currents

EarthingEarthing and high protective conductor currents Example:and high protective conductor currents Example:6 way CCU/DB has 2 high protective conductor current radial 6 way CCU/DB has 2 high protective conductor current radial

circuits. The rest are used for MEC and Gas/Water Bondscircuits. The rest are used for MEC and Gas/Water Bonds

The The regsregs state that each circuit requires 2 state that each circuit requires 2 cpcscpcs how might this be how might this be achieved? achieved?

High Protective Conductor CurrentsHigh Protective Conductor Currents

Possible Solution Possible Solution 543.7.1.204, 205 and 543.7.2.201543.7.1.204, 205 and 543.7.2.201

•• Note: Ferruled alphaNote: Ferruled alpha--numeric identification becomes importantnumeric identification becomes important

68

BS7671 2008: C&G Outcomes 5 continuedBS7671 2008: C&G Outcomes 5 continued

•• 5.19 Identify the requirements for low voltage generating sets 55.19 Identify the requirements for low voltage generating sets 5.20 .20 Identify the requirements for rotating machines Identify the requirements for rotating machines

•• 5.21 State the requirements for accessories such as plug and soc5.21 State the requirements for accessories such as plug and socketket--outlets and outlets and

•• cable couplers cable couplers

•• 5.22 Identify the requirements for current5.22 Identify the requirements for current--using equipment such as using equipment such as electrode boilers and heating cables electrode boilers and heating cables

•• 5.23 State the requirements for transformers 5.23 State the requirements for transformers

•• 5.24 Identify the requirements for the selection and erection of5.24 Identify the requirements for the selection and erection ofluminairesluminaires and lighting installations, including highway power supplies anand lighting installations, including highway power supplies and d street furniture street furniture

•• 5.25 State the requirements for supplies for safety services and5.25 State the requirements for supplies for safety services and their their associated circuits and cables associated circuits and cables

Selection and Erection Part 5Selection and Erection Part 5

551 Low Voltage Generating Sets551 Low Voltage Generating Sets•• 551.1 Scope551.1 Scope•• Generally SSEG up to 3.6kW (BS EN 50438) per Generally SSEG up to 3.6kW (BS EN 50438) per

phase but can be higher phase but can be higher •• Consult G59/1: supplies > 16A/phase up to 5MWConsult G59/1: supplies > 16A/phase up to 5MW•• Consult G83/1: supplies < 16A per phase <3.6kWConsult G83/1: supplies < 16A per phase <3.6kW•• Combinations of mixed supplyCombinations of mixed supply

1.1. Not connected to a public supplyNot connected to a public supply2.2. Alternative or separate sourceAlternative or separate source3.3. Parallel with the public supplyParallel with the public supply4.4. Combinations of the aboveCombinations of the above

Selection and Erection Part 5Selection and Erection Part 5551.1.1 Power sources551.1.1 Power sources•• Combustion Engines, Turbines, Electric Motors, PV Combustion Engines, Turbines, Electric Motors, PV

Cells, Batteries, Other sources (Wind, Water, Cells, Batteries, Other sources (Wind, Water, Geothermal, Biochemical)Geothermal, Biochemical)

•• 551.1.2 Power source (elec. Characteristics)551.1.2 Power source (elec. Characteristics)•• Mains and self excited Synchronous, asynchronous, Mains and self excited Synchronous, asynchronous,

generatorsgenerators•• Mains and self commutated static converters (Mains and self commutated static converters (SMPsSMPs))•• (invertors DC (invertors DC -- AC, converters AC AC, converters AC –– ACAC, rectifiers AC , rectifiers AC -- DC,)DC,)•• 551.1.3 Purpose551.1.3 Purpose•• Supplies to permanent, temporary, mobile separate Supplies to permanent, temporary, mobile separate

installations,installations,


551.2.1 General Requirements551.2.1 General Requirements•• Excitation and commutation appropriate for Excitation and commutation appropriate for

generationgeneration

•• psc/pfcpsc/pfc must not exceed the generating capacitymust not exceed the generating capacity --UPS operates in terms of protection of a fault downstream is corUPS operates in terms of protection of a fault downstream is correct rect then, as the UPS cannot provide enough fault current to trip thethen, as the UPS cannot provide enough fault current to trip the MCB'sMCB'sin the DB then, upon detecting overload it switches to bypass, ain the DB then, upon detecting overload it switches to bypass, and nd allows the mains supply to provide the trip current.allows the mains supply to provide the trip current.

•• Additional Requirements for:Additional Requirements for:•• 551.3 551.3 –– 7 parallel, switched alternative, SELV, 7 parallel, switched alternative, SELV,

Temporary supply, Inc. Static converters,Temporary supply, Inc. Static converters,

72


Rotating MachinesRotating Machines•• 552.1.1 all equipment shall be suitable to cope with552.1.1 all equipment shall be suitable to cope with

•• Starting, accelerating and load currentsStarting, accelerating and load currents•• Cumulative effects of frequent starting, stopping and Cumulative effects of frequent starting, stopping and

breaking with respect to temperaturebreaking with respect to temperature•• 552.1.2 motor rating > 0.37kW must have overload 552.1.2 motor rating > 0.37kW must have overload

protection within the control or manufactured design protection within the control or manufactured design of the machineof the machine

•• 552.1.3 method of preventing automatic restart on 552.1.3 method of preventing automatic restart on power failure or voltage dip, unless the activity of the power failure or voltage dip, unless the activity of the machine is designed to auto startmachine is designed to auto start

73


74

Selection and Erection: Current using EquipmentSelection and Erection: Current using Equipment

554.1 Electrode water heaters and Boilers554.1 Electrode water heaters and Boilers•• Normal working pressures = 10 bar +. Construction is usually a Normal working pressures = 10 bar +. Construction is usually a vertical vertical

pressure shell containing the electrodes. The lengths of the elepressure shell containing the electrodes. The lengths of the electrodes ctrodes control the maximum and minimum water level. The electrical resicontrol the maximum and minimum water level. The electrical resistance stance of the water allows a current to flow through the water, which iof the water allows a current to flow through the water, which in turn, n turn, boils and releases steam. Since water has to be present within tboils and releases steam. Since water has to be present within the he electrode system, lack of water cannot burn out the boiler. The electrode system, lack of water cannot burn out the boiler. The main main advantage with these units is that they may be located at the poadvantage with these units is that they may be located at the point int where steam is required and, as no combustion fumes are producedwhere steam is required and, as no combustion fumes are produced, no , no chimney is required. Steam may also be raised relatively quicklychimney is required. Steam may also be raised relatively quickly, as there , as there is little thermal stressing to consider.is little thermal stressing to consider.

•• 554.1.2 Linked circuit breakers to be used554.1.2 Linked circuit breakers to be used•• 554.1.3 Electrode boilers must be earthed and bonded to neutral554.1.3 Electrode boilers must be earthed and bonded to neutral

and earthand earth•• 554.1.4 RCD to operate in excess of 10% of rated current but ca554.1.4 RCD to operate in excess of 10% of rated current but can n

be extended to 15% dependant upon machine. Time delay be extended to 15% dependant upon machine. Time delay RCDsRCDsmaybe usedmaybe used


Selection and erection555 Transformers551.1.1 neutrals are connected to common terminal in

auto transformers551.1.2 Step-up stransformers not to be used in IT

systems551.1.3 Linked switch to disconnect step-up transformer

from all live supply conductors


Selection and erection557 Auxiliary and control circuits557.3.2.1 Control power supplySupplied directly• Via rectifier• Via transformerTable 55.2 minimum csa of copper conductors for control (mm2)

Conductor for measuringArea of copperCross sectional Need a largerCircuits mayOther auxiliary

0.1----Data transfer

0.10.50.50.50.5Control circuits

Screened/ unscreenedUnscreenedScreenedStrandedSingle wire

Multi-coreTwo CoreSingle coreApplication

Types of cable

77

Selection and Erection Part 5Selection and Erection Part 5559 559 LuminairesLuminaires and Lightingand Lighting•• 559.1 Scope;559.1 Scope;•• All lighting within and attached to fixed installationsAll lighting within and attached to fixed installations•• Does not includes Fixed outdoor lighting including Does not includes Fixed outdoor lighting including

roads, parks car parks, sporting areas, floodlighting, roads, parks car parks, sporting areas, floodlighting, telephone kiosks, advertising panels, road signs and telephone kiosks, advertising panels, road signs and road traffic signal systemsroad traffic signal systems

•• Exclusions include distributors equipment, temporary Exclusions include distributors equipment, temporary festoon lighting, high voltage signs supplied by HV and festoon lighting, high voltage signs supplied by HV and LVLV

78

Selection and Erection Part 5Selection and Erection Part 5559 559 LuminairesLuminaires and Lightingand Lighting•• 559.5.1.202 : only one light fitting attached to ceiling roses559.5.1.202 : only one light fitting attached to ceiling roses

•• 559.5.1.204 Lighting circuits incorporating B15, B22, E14, E27, 559.5.1.204 Lighting circuits incorporating B15, B22, E14, E27, or or E40 E40 lampholderslampholders shall be protected by an shall be protected by an overcurrentovercurrent protective protective device of maximum rating 16Adevice of maximum rating 16A

•• 559.5.1.205 : T2 temperature rating for B15, B22 holders559.5.1.205 : T2 temperature rating for B15, B22 holders

•• 559.5.1.206 : Edison screw lamp holders centre pin live exceptio559.5.1.206 : Edison screw lamp holders centre pin live exception n being E14, E27 plastic fittingsbeing E14, E27 plastic fittings

•• 559.5.1.208 : Provision of neutrals at switches for electronic 559.5.1.208 : Provision of neutrals at switches for electronic controlcontrol

•• 559.5.5 Groups of 559.5.5 Groups of luminairesluminaires divided between the line conductors divided between the line conductors of a of a polyphasepolyphase circuit with only one common neutral conductor shall circuit with only one common neutral conductor shall be provided with at least one device disconnecting simultaneouslbe provided with at least one device disconnecting simultaneously y all the line conductors.all the line conductors.

79

Selection and Erection Part 5Selection and Erection Part 5559.6 559.6 LuminairesLuminaires and Lightingand Lighting-- wiring systems wiring systems -- Method of Method of

fixingfixing

1.1. Ceiling Rose BS 67Ceiling Rose BS 67

2.2. Supporting coupler BS 6972, BS7001Supporting coupler BS 6972, BS7001

3.3. Batten Batten lampholderlampholder BS EN 60598BS EN 60598

4.4. LuminiareLuminiare to BS 60598to BS 60598

5.5. Socket outlet to BS1363Socket outlet to BS1363--2, BS 546, BS EN 603092, BS 546, BS EN 60309--22

6.6. Distribution unit BS 5733Distribution unit BS 5733

7.7. Connection unit to BS 1363Connection unit to BS 1363--44

8.8. Terminal box to BS EN 60670, BS4662Terminal box to BS EN 60670, BS4662

9.9. DCL to IEC 61995DCL to IEC 61995--11

Selection and Erection Part 5Selection and Erection Part 5A Sample of lighting

symbols (extract)

Table 55.3 page 190 for exact representation

81

Selection and Erection Part 5Selection and Erection Part 5Lighting and Lighting and LuminaresLuminares

•• 559.8 PF capacitors with >0.5uF require discharge resistors559.8 PF capacitors with >0.5uF require discharge resistors•• 559.9 Consideration should be given to the 559.9 Consideration should be given to the stroboticstrobotic effect effect

caused by discharge lightingcaused by discharge lighting

82

BS7671 2008: DesignBS7671 2008: Design

•• Example 1Example 1A Domestic premises is to have its bathrooms updated to the lateA Domestic premises is to have its bathrooms updated to the latest st

BS7671BS7671List areas to check and upgradeList areas to check and upgrade•• Example 2Example 2A Domestic bathroom contains an electric shower, extractor fan iA Domestic bathroom contains an electric shower, extractor fan in n

zone 2, zone 2, DownlightingDownlighting outside zone 1, SFCU to a tumble drier outside zone 1, SFCU to a tumble drier outside Zone 2, A light switch 150mm from the other side of the outside Zone 2, A light switch 150mm from the other side of the door entry, All supplementary bonding is in place across H/C tapdoor entry, All supplementary bonding is in place across H/C taps s and CH radiatorsand CH radiators

What items need to be checked and upgraded?What items need to be checked and upgraded?What sort of verification and measurement would be necessary?What sort of verification and measurement would be necessary?

83

Applying Electrical Design 4aApplying Electrical Design 4aSelect Cable Size from Appendix 4Select Cable Size from Appendix 4•• Cable selection for type should have already been considered dueCable selection for type should have already been considered due to initial to initial

characteristics of Purpose, Environment, Maintainability, in pcharacteristics of Purpose, Environment, Maintainability, in part 3 and art 3 and Appendix 5 Appendix 5 --external influencesexternal influences•• So the appropriate table should be easy to find.So the appropriate table should be easy to find.

•• Appendix 4 Table4A1 provides methods of installation which are cAppendix 4 Table4A1 provides methods of installation which are cross ross referenced when selecting the maximum Current Carrying Capacity referenced when selecting the maximum Current Carrying Capacity of the of the circuit cablecircuit cable

•• If Domestic installation cables are to be used then Appendix 4 TIf Domestic installation cables are to be used then Appendix 4 Table 4D5A able 4D5A as opposed to 4D2A and 4D2Bas opposed to 4D2A and 4D2B•• (Non(Non--armoured Multiarmoured Multi--core insulated and sheathed with CPC as a core or combined core insulated and sheathed with CPC as a core or combined

together)together)•• If the installation is industrial then you would be considering If the installation is industrial then you would be considering SWA, Singles in SWA, Singles in

Conduit and Conduit and TrunkingTrunking, MIMS, FP200 etc, MIMS, FP200 etcNote: 523.6.1 full size neutrals for: Note: 523.6.1 full size neutrals for:

•• (i) discharge lighting(i) discharge lighting•• (ii) (ii) polyphasepolyphase circuits where harmonic currents exceeds 10% of the fundamentalcircuits where harmonic currents exceeds 10% of the fundamental

currentcurrent•• (iii) balance three phase circuits where the Harmonics are > 15%(iii) balance three phase circuits where the Harmonics are > 15% of the of the

fundamental line currentfundamental line current

84

Selection and Erection of cable systemsSelection and Erection of cable systemsNumber of cables within an enclosure Number of cables within an enclosure --522.8.1, 2, 3, 522.8.1, 2, 3, •• No expansion of requirements to these regulations (assume that No expansion of requirements to these regulations (assume that

OSG 16OSG 16thth Ed. is still applicable)Ed. is still applicable)•• Cables installed into Conduit or / and Cables installed into Conduit or / and TrunkingTrunking require a space factor require a space factor

to allow pull throughto allow pull through•• Rule of thumb = 45% cable space to internal enclosure space Rule of thumb = 45% cable space to internal enclosure space -- OSG OSG

footnote table 5Ffootnote table 5F•• Tables in Appendix 5 only take into consideration Tables in Appendix 5 only take into consideration -- ease of drawing in ease of drawing in

and not Grouping factors and not Grouping factors --more cables less current carrying capacity more cables less current carrying capacity per circuit cableper circuit cable

•• For grouping of conductors to protect against overheating see For grouping of conductors to protect against overheating see Appendix 4 Table 4C1 and *OSG Appendix 6 Table 6C*Appendix 4 Table 4C1 and *OSG Appendix 6 Table 6C*

•• For standard cable sizes and enclosure sizes use tables 5A to For standard cable sizes and enclosure sizes use tables 5A to 5F5F

•• Other types of cable and / or enclosure use 45% ruleOther types of cable and / or enclosure use 45% rule

85

Cable Selection and Volt DropCable Selection and Volt Drop

525.1 Requirements for volt drop in buildings525.1 Requirements for volt drop in buildings

86

Cable Selection and Volt dropCable Selection and Volt drop525 525 -- Volt Drop for normal operation Volt Drop for normal operation –– Appendix 2 & 12Appendix 2 & 12

•• Voltage variations Voltage variations UoUo +10% +10% -- 6%6%•• Voltage range = 216.2v to 253v Voltage range = 216.2v to 253v •• Suppliers Maximum Volt drop = 6%Suppliers Maximum Volt drop = 6%•• Installers maximum Volt drop = 3Installers maximum Volt drop = 3--5%5%•• UoUo * 3* 3--8% = ??V maximum Volt drop allowable in installations 8% = ??V maximum Volt drop allowable in installations ––

525.1525.1•• Formula to find the actual Volt Drop when the cable is known: Formula to find the actual Volt Drop when the cable is known: --

App 4. 6 App 4. 6

•• Alternative Formula when the cable is not known and the Alternative Formula when the cable is not known and the minimum size is to be found.minimum size is to be found.

V . DAct=mV / A/m×I B×L1000

mV /A /mmax=V . Dmax×1000

I B×L


531 and 532 Residual Current DevicesRCDs as general protectionProtection from faults, earth fault currents, shock protection

532 Protection against fire using 532 Protection against fire using RCDsRCDs

An example might be a sub-mains to a garage or an external distribution board from a TT/TN system where there are flammable materials stored !

Additional Protection against ShockAdditional Protection against ShockOperating Characteristics of RCDs – Appendix 3

RCD RCD TypeType

IIΔΔNNmAmA mAmA

Trip Trip time mstime ms mAmA

Trip Trip time mstime ms mAmA

Trip Trip time mstime ms

General General NonNon--delaydelay

‘‘GG’’ typetype

1010 1010 300 300 maxmax

2020 150 150 maxmax

5050 40 max40 max

3030 3030 6060 150150

100100 100100 200200 500500

300300 300300 600600 15001500

500500 500500 10001000 25002500

DelayDelay‘‘SS’’ typetypeSelectivSelectiv

ee

100100 100100 130 min130 min500 500 maxmax

200200 60 min60 min200 200 maxmax

500500 40 min40 min150 150 maxmax300300 300300 600600 15001500

500500 500500 10001000 25002500

1× I ΛN 2×I ΛN 5×I ΛN

411.4.5 415.1.1

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Protection from Electric ShockProtection from Electric ShockPractical considerations when installing Practical considerations when installing RCDsRCDs1.1. All circuits in bathrooms need to be 30mA RCD protected. All circuits in bathrooms need to be 30mA RCD protected.

1.1. All sockets up to 20A, not used by an instructed or skilled persAll sockets up to 20A, not used by an instructed or skilled person and not specially on and not specially designated (designated (e.ge.g fridge socket) need to be 30mA RCD protected. fridge socket) need to be 30mA RCD protected.

2.2. All sockets up to 32A that might be used to supply portable equiAll sockets up to 32A that might be used to supply portable equipment outdoors, 30mA pment outdoors, 30mA RCD. RCD.

3.3. All cables not in mechanical protection in a wall and not 50mm dAll cables not in mechanical protection in a wall and not 50mm deep, including those in eep, including those in the current safe zones, need to be 30mA RCD protected. the current safe zones, need to be 30mA RCD protected.

4.4. All cables not in mechanical protection in any depth of metal waAll cables not in mechanical protection in any depth of metal wall studwork need to be ll studwork need to be 30mA RCD protected.30mA RCD protected.

1.1. Single RCD covering the whole installation not acceptable (314)Single RCD covering the whole installation not acceptable (314)and and RCBORCBO’’ss are still too expensiveare still too expensive

Solutions might be:Solutions might be:•• a main switch and 2 30mA a main switch and 2 30mA RCDsRCDs. Each RCD to have say the upstairs power and down lighting on o. Each RCD to have say the upstairs power and down lighting on one ne

RCD and the other to have the opposite.RCD and the other to have the opposite.•• main switch in an enclosure a Henley block and 2 main switch in an enclosure a Henley block and 2 CCUsCCUs both with 30mA Incomers if you have loads both with 30mA Incomers if you have loads

of circuits. of circuits. •• Split CCU with Main Switch with Split CCU with Main Switch with RCBOsRCBOs and and MCBsMCBs, 30mA secondary switch covering , 30mA secondary switch covering MCBsMCBs•• Adapt a 3Adapt a 3--phase board (connect the neutral line to L2 and link the phase tphase board (connect the neutral line to L2 and link the phase to L1 and L3) Must be o L1 and L3) Must be

labelled and available only to single phase supplies then you shlabelled and available only to single phase supplies then you should be able to connect double pole ould be able to connect double pole single phase devices next to each other! single phase devices next to each other! –– if in doubt consult a qualified electrician ! if in doubt consult a qualified electrician !

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Selection and Erection: Safety ServicesSelection and Erection: Safety Services

Chapter 56: ScopeChapter 56: Scope

•• Emergency Lighting BS EN 5266Emergency Lighting BS EN 5266•• Fire PumpsFire Pumps•• Fire Rescue Service LiftsFire Rescue Service Lifts•• Fire Detection and Alarm SystemsFire Detection and Alarm Systems•• CO detection and Alarm SystemsCO detection and Alarm Systems•• Fire evacuation systemsFire evacuation systems•• Smoke Ventilation systemsSmoke Ventilation systems•• Fire services communication systemsFire services communication systems•• Essential medical systemsEssential medical systems•• Industrial safety systemsIndustrial safety systems

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Selection and Erection: Safety ServicesSelection and Erection: Safety Services560.4 Classification of a Safety System560.4 Classification of a Safety System

1.1. NonNon--automatic supplyautomatic supply2.2. Automatic Automatic –– self staringself staring

Automatic supply is classified by the following time it takes Automatic supply is classified by the following time it takes to get fully operationalto get fully operational

1.1. No break No break –– UPSUPS2.2. Very short break Very short break –– < 0.15s< 0.15s3.3. Short Break Short Break -- > 0.15 < 0.5s> 0.15 < 0.5s4.4. Normal Break Normal Break -- > 0.5 < 5s> 0.5 < 5s5.5. Medium Break Medium Break -- > 5s < 15s> 5s < 15s6.6. Long Break Long Break -- > 15s> 15s

Follow the appropriate British Standard or do a Risk Follow the appropriate British Standard or do a Risk AssessmentAssessment

•• Safety services to be installed to allow adequate durationSafety services to be installed to allow adequate duration•• Equipment to be suitable to last for the duration of escapeEquipment to be suitable to last for the duration of escape•• 560.5.3 Continual IT insulation monitoring devices that give an 560.5.3 Continual IT insulation monitoring devices that give an

audible or visual indication of the first fault in the systemaudible or visual indication of the first fault in the system

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Selection and Erection: Safety ServicesSelection and Erection: Safety Services

560.6 Electrical sources for Safety Services560.6 Electrical sources for Safety Services•• 560.6.12560.6.12 UPSUPS•• Operate distribution circuit protective devicesOperate distribution circuit protective devices•• Start the safety devicesStart the safety devices•• When operating in an emergency condition from the When operating in an emergency condition from the

converter supplied by batteryconverter supplied by battery•• UPS source shall meet the requirements of regulation UPS source shall meet the requirements of regulation

560.6.9560.6.9•• Static type of UPS shall conform to BS EN 62040Static type of UPS shall conform to BS EN 62040

•• 560.7 Circuits for Safety Services shall be 560.7 Circuits for Safety Services shall be independent of other circuits independent of other circuits –– Does not include Does not include Smoke Alarms and emergency lighting that are battery Smoke Alarms and emergency lighting that are battery powered and supplied by a charging circuit i.e. lightspowered and supplied by a charging circuit i.e. lights

bs7671 2008: c&g 2382 outcomes 5 - legh...

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