***Cont../ Useful Information for Electricians & Apprentices***

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O.S.G.. The use of other methods’ of determining Maximum Demand is Not Precludedwhere Specified by the Installation Designer

FirstlyI make no Apologies for the Way am Writing on any Matters . it can be a first day Apprentice or some one Needing aJog of Memory .
Sowe are all in the Same Boat . “ To Learn “

For the Apprentices . The Day we stop learning is the Day we hang Upour Tool-Bag

CookerDesign Current Calculations

Thefirst thing you have to do is get Your Head around the Calculations !!

(From a Design point of View ) 2392-10

DomesticInstallation Oven(s) & Hob(s) are to be Calculated upon their MAXIMUM LOADING
Startwith a simple Calculation ( An Oven has a rating of 2kW ) 2000

(I = P/V ) Formula … I = 2000 ÷ 230V = 8.70A …. Weare Using the Unit Amps


2392-10/ Domestic Installation Oven(s)

Ovenhas 4 Rings ( 2 x 1kW ) & ( 2 x 1.5kW ) & Grill ( 2kW ) & Oven (3kW )

-Controlled via a CookerSwitch with a Socket outlet .

Asa Designer . we’ll have to Apply Diversity ??

Important )- Diversity allowance to be Applied to the FULL LOAD CURRENT for CookingAppliances .

TheO.S.G. is telling us . Purpose of the Final Circuit fed from theConductors )
O.S.G.Table 1B p/97 – column (3) Cooking Appliances → At the Top of the Page Note : Type ofPremises ( 2392-10 → Household Installations ) Domestic Installation(s)

DomesticInstallation(s) Only O.S.G. - 10A + 30% f.l – Full Load ) of connected Cooking Appliances in the Excess of 10A+ 5A if a socket-outlet is incorporated in the Control Unit . ( C.C.U. ) – 45A + 13A Socket Switched with Neon .

Fromyour point of View ( The First 10A ofthe rated current plus 30% of the reminder ( Plus) 5A if the Control Unit incorporates s Socket.

Calculations)- You bank “ Hold OFF“ the first 10 Amps of the Maximum Load Current )
The10A will be used at the End of the Calculations’

-So your Work out the Total Power Rating & then calculate the Full Load Current

Calculations)- Power = ( 2 x 1 ) + ( 2 x 1.5 ) + ( 2+ 3 ) = 10kW

I= 10000 ÷ 230V = 43.48A … round it up to the first four numbers43.47826087 ( 48 ) 43.48A

UsingDiversity allowance stated ↑↑ ( 43.48A sub 10A = 33.48A )

I= 33.48 x 30 ÷ 100 = 10.04A

Youradding the ( 5A ) for Socket outlet . I = 10A + 10.04 + 5A = 25.04A )- Asa Designer this is your Expected Current Demand .

Remember )- Supply Cables Rated to suit DesignCurrent ( Iz )

 

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“ This is a Live Test “ .
415.1.1. –. Additional protection : RCDs

It only works if the RCD is “ Energised “
Regulation RCD effectiveness of any testfacility incorporated in the device
To Ensure . The test buttonshould operated at intervals of not greater than 3 months . BS- 514.12.2. p/118..

H&S . Legislation .
The Electricity at Work Regulations 1989 . specificallydeal with Electrical “ Systems “ Regulation 4 .

i) All “ Systems“ shall at all times be of suchconstruction as to prevent . so far is reasonablypracticable . Danger .
ii) As may benecessary to prevent “ Danger “ all systems shallbe maintained . sofar prevent . so far as is reasonablypracticable . Danger .
iii) Every work activity . including ( Operation ) use & maintenance of a sytem &work near a system . shall be carried out in such a manner as not to give rise. so far is reasonablypracticable . Danger .
iv) Any equipment providedunder these Regulations for the purpose of ( ProtectingPerson(s) at work on or near Electrical Equipment shall be suitable for the use for which
it is provided . etc .

415.1.2. An RCD is not used as the solemeans of protection & does not obviate the need to apply one of theprotective measures specified in section 411 to 414 .
- AnRCD is not used as the sole means of protection against Exposed live conductors.

Wiring regulation 17[SUP]th[/SUP] Edition – 2011
Which . amongst other requirements .specifies therequired methods for safe Fusing & Earthing . 415.1.2. The single most important precautionagainst Electric Shock is a properly constituted Earthing System supported by ( Fuses or MCBs ). To correctlydisconnect the supply in case of Overcurrent or Fault to Earth .

□ For “Portable Units “ the Test Button shouldbe operated before every use at a new site to ensure that it isFunctioning .
You know the outcome . Any device failing to Trip must be removed from service .

 

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612.13.: Functional testing . 2392-10 . last test .
i) Where ( ► Faultprotection ) & / or ( ►Additional protection) is to be provided by an RCD .
ii) The effectiveness of any test facility incorporatedin the device shall be verified .

 

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Determining the Protective DeviceCharacteristics’ . “ MCB “ p/38

Main formula .

( Iz > In > = Ib )
433.1.1.:
Ib ) –Design current of circuit ( A ) Load to be connected tothe circuit . :
Table 41.3.
In ) – Ratedcurrent or current setting of protective device ( A ) .
433.1.1.
Iz ) –Current-carrying capacity of a cable for continuous service under theparticular installation conditions concerned ( A )

This means that in every circuit at all times thecurrent carrying capacity of the cables must be ( Higher ) than the ( Highest ) possible load current .
The ( Protective Device ) rating must be ( Higher ) thanthe ( Load Current ) but ( Lower ) than the maximum current carrying capacity ofthe ( Cable ) installed

-&-s 2392-10: RCDs “ MUST “be used in conjunction with an “ Overload ProtectionDevice “ such as MCB .
-&-s 2392-10: RCD . Double-poleswitching types are preferred to ensure full isolation should a fault occur .

 

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RCD: Hazards .

RCDs– don’t offer protection against current Overloads .
RCDs– will NOT protect against a socket outlet being wired with its Line &Neutral terminals the wrong way round .
RCDs– will NOT protect against the overheating that results when conductors are NOTproperly screwed into their terminals
RCDs– will NOT protect against Line & Neutral shocks . because the current inthe Line & Neutral is balanced . so if you touch Line & Neutralconductors at the same time . ( bothterminals of a light fitting ) you maystill get a shock .

 

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2392-10 : Visual Inspection . 611.1. to 611.3.
“ Inspection “ shall precede testing & shall normally be donewith that part of the Installation under Inspection ( Disconnectedfrom the Supply )

 

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Useful Junk .
Earth Fault LoopImpedance Test . cannot be conducted ( Before )an Installation is connected to the ( Supply ). -&-s

 

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Continuity of Conductors in Ring Final Circuit . 612.2.2.
Purpose of this test is to verify that the Ring FinalCircuit . are
Correctly wired & connected .
Continuous .
-&-s. Not interconnected / Bridged

 

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Earth Electrode Résistance .612.7.

Where the Earthing System incorporates an EarthElectrode as part of the Installation , The Electrode résistance to Earth shallbe ( Measured )

The Earth Electrode . where used . is the means ofmaking contact with ( General Mass of Earth ) Thus it must be ( Tested) to ensure that good contact is made .
Your main consideration here 2392-10 : To ensure thatthe Electrode résistance . is ( NOT HIGH ) thatthe voltage from Earthed Metalwork to Earth ( Exceed50V ) ◄

Where an RCD . is used This means that the result ofmultiplying the RCD operating current ( in Amperes ) by the Electrode résistance( in Ohms ) does NOT Exceed 50V ◄
If a ( 30mA /RCD ) is used . This allows a maximum Electrode résistance of ( 16667*Ω ) althoughit is recommended ( Table 41.5. – Max Earth Fault LoopImpedance ( Zs )

Earth Electrode résistance should NEVER be GREATER than (200Ω )

 

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2392-10: An Inspection and Test which is carried out on a NEWInstallation to PROVE Compliance is called , Initial Verification ,

 

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2392-10:

Whena New Installation has been Completed , it must be Inspected and Tested toEnsure that it is” SAFE “ to use ,
ThisProcess is known as the Initial Verification ,Regs 610.1 for Safety reasons , the Inspection process must precede Testing ,

 

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Please take the TIME to READ this MATTER . 2391-10 / 2392-10 ◄◄ :13:

This Forum can ONLY give YOU GUIDANCE . ◄◄

What is ( Time ) Money .


Firstly. We are ( All) guilty of NOT reading theQuestions / Rightly. 2391-10 . C&G ?? . :blush5:


C&G ?? Identifythe most suitable test instrument for a set of circumstances C&G ?? . GN-3 . ( Incorrect Instrument Names being Used in Exams ) 17[SUP]th[/SUP] Edition& 2011 .


☼ p/83 . GN-3 . Insulation RésistanceOhmmeters’ .
the instrument used should be capable of developing the( Test ) voltage requires across the ( Load )

[ Instrument conformingto BS-EN-61557-2 ] ◄◄◄

☼ p/83 . GN-3 . Earth Fault Loop Impedance Testers
These instruments operate by ( Circulating ) a currentfrom the Line conductor into the Protective Earth . This will raise thepotential of the Protective Earth System .

For circuits rated to ( 50A ) a Line-Earth loop testerwith a resolution of ( 0.01Ω ) should be adequate . in general . suchinstruments can be relied upon to be accurate down to values of around ( 0.2Ω )

Instruments conforming to BS-EN-61557-3 . will fulfilthe above requirements . ◄◄◄

☼ p/84 . GN-3 . Earth Electrode RésistanceTesters .
this may be a ( Four terminalinstrument ) OR ( Three terminal One ) where a combined lead to the ( Earth Electrode ) would not have a significant résistancecompared with the ( Electrode Résistance ) sothat the résistance of the test leads & temporary spike résistance ( Can be eliminated from the Test Result )

-&-s ?? .Please NOTE (- “ Wording Used “ . ◄◄
It may be HELPFUL to NOTE thatInstrument complying with ( BS-EN-61557-5 ) . incorporatethis facility . ◄◄

 

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☼ p/84 . GN-3 . -&-s ?? . PleaseNOTE (- “ Wording Used “ . ◄◄
Phase Rotation Instrument . BS-EN-61557-7. ◄◄ . gives the requirements for measuring equipmentfor testing the ( Phase Sequence in Three-phase distribution systems .
[ Whetherindication is given by . Mechanical . Visual . & /or AudibleMeans . ]

☼ p/84 . GN-3 . -&-s ?? . PleaseNOTE (- “ Wording Used “ . ◄◄
RCD Testers .
The test instrument should be capable of applying thefull range of test current to an ( In-service ) accuracy as given in (BS-EN-61557-6 ) ◄◄
Now -&-s (- Wording Only . 2392-10 Exams . To CHECK - RCD operation & to minimise ( Danger ) during the test . The test current should beApplied ( For No Longer Than2 Seconds ) 2392-10 . This only Appliesto RCD Only . ◄◄◄◄◄◄

☼ 2392-10 . The instrument used for ( Low – Résistance Tests) 612.2.1. No-load voltage between 4V &24V . & a short– circuit current NOT less than 200mA .
Instrument to ( BS-EN-61557- 4 ) will meet the above requirements . ◄◄◄◄◄◄

☼ p/81 –GN-3 : Instrument Standard .
The ( Basic ) instrumentstandard is ( BS-EN-61557 ) Electrical Safety in Low-Voltage Distribution Systems. Up to 1000V . a.c. & 1500V . d.c. Equipment for Testing .Measuring or Monitoringof Protective Measures . ◄◄◄◄◄◄

NOTE (-. This Standard includes performance requirements & requires ( Compliance with BS-EN-61010 )

ISBN-978-086341-857-0 . GN-3

 

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Amendment 2011 .

□ Electrical Installation Condition Report .

Electrical Installation Condition Report . ( EICR ) from Appendix 6 of BS-7671 . is for use when carrying out ( Routine ►► PeriodicInspection & Testing ) of an Existing domestic& similar installation . with up to ( 100A ) ( Single – phase ) or ( Three-phase) supply .
►► It isNOT use when ( Alterations or Additions are Made)

A Generic Scheduleof Test Results ( 4 ) & aCondition Report Inspection Schedule ( 7 ) shouldaccompany the Electrical Installation Condition Report ( 6 )

( 6 ) The ElectricalInstallation Condition Report . ( EICR ) to be used for Domestic & SimilarInstallations with ( 100A ) Single – phase ) or ( Three-phase ) supply
( 4 ) Generic Schedule of Test Results .
( 7 ) Condition Report Inspection Schedule . ( forDomestic & Similar Premises with up to ( 100A ) supply .

 

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The ( Forms ) are Numbered .

1 ) . Electrical Installation Certificate . Please Note : (Single – Signature )
2 ) . Electrical Installation Certificate .
3 ) . Scheduleof Inspections . Please Note : ( for NEW Installation Work Only )
4 ) . GenericSchedule of Test Results .
5 ) . Minor ElectricalInstallation Work Certificate .
6 ) . ElectricalInstallation Condition Report .
7 ) . ConditionReport Inspection Schedule . Please Note : ( forDomestic & Similar Premises with up to ( 100A) supply .

( 1 & 4 ) are designed for use when ( Inspecting & Testing ) a New Installation . or an Alteration orAddition to an ( Exceeding Installation ) forms comprise the following .

1 ) . Short –form of . Electrical Installation Certificate . PleaseNote : ( to be used when oneperson is responsible for the Design . Construction . Inspection & Testing. of an Installation ) OR .
2 ) . Electrical Installation Certificate . ( Standard from Appendix 6 of BS-7671 )
3 ) . Scheduleof Inspections . Please Note : ( foe NewInstallation Work ONLY )
4 ) . Generic Schedule of Test Results . .

 

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-&-s . State the ( TWO ) different types of Inspection & Testing . may require

“ InitialVerification “ … ( Initial Verification & Inspection )
“ Periodic Inspection & Testing “ … ( ElectricalInstallation Condition Report )

 

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-&-s . State the ( TWO ) different types of Inspection & Testing . may require

“ InitialVerification “ … ( Initial Verification & Inspection )
“ Periodic Inspection & Testing “ … ( ElectricalInstallation Condition Report )


-&-s . 2010 . Q ) Identify the Two Types of Test InstrumentIdentified in GN-3 . Which may be Usedto confirm “ Phase Sequencing “
GN-3 . 2.7.17. Phase – Sequence . p/54

i) Rotating disctype .
ii) Indictor Lamp Type .

you have correctly Identify these InstrumentTypes . for -&-s

 

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Functional Testing . GN-3 . p/55 (GN-3 & Regulations )

While the following tests are NOTa specific requirement of BS-7671 . it is recommended that they arecarried OUT.

In order to test the effectiveness of Residual CurrentDevices after installation . a ( Series of Tests ) may be applied to check thatthey are within specification & operate satisfactorily . ( Regulation - 612.8.1.) p/193 . & Operate satisfactorily .
This test sequence will be in addition to providingthat the test button is operational . the effectiveness of the test buttonshould be checked after the test sequence .

2392-10 : foreach of the tests . Readingsshould be taken on ( Both Positive & Negative half-cycles & the longeroperating time recorded .0

411.4.5. . Prior to these RCD tests it isessential . for safety reasons . thatthe earth loop impedance is tested to check the requirements have been met .

TN-S . System . example.. 612.8.1. The ( Verification ) of the ( Effectiveness ) of the measure for faultprotection by automatic disconnection of supply is effected as follows .

1) measurement ofthe earth fault loop impedance – see Regulation . 612.9.
2) verification of the characteristics & / or theeffectiveness of the associated protective device . This verification shall bemade .

- for overcurrent protective devices . by visualinspection ( i.e. short-time or instantaneous tripping setting forcircuit-breakers . current rating & type for fuses .
- RCDs . by Visual Inspection& Test . ◄◄◄
The effectiveness of automaticdisconnection of supply by RCDs shall be verified using ( Suitable Test Equipment ) according to ( BS-EN-61557-6 ) . see Regulation 612.1.
To confirm that the relevant requirements in Chapter 41 are Met .

The disconnection times required by Chapter41 . shall be Verified .

 

[brian 2012]

Re: ***Cont../ Useful Information for Electricians’ & Apprentices***

hi im just starting my 2392 10, i have a question . IDENTIFY IN ORDER TO PRODUCE A DESIGN SPECIFICATION THE INFORMATION REQUIRED FROM THE (a) CLIENT
(b) electricity distrubution network operator (DNO)
COULD YOU GIVE US A PUSH IN THE RIGHT DIRECTION TA

 

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-&-s 2391-10 / 2392-10 . Inspection & Testing &Verification of Electrical Installation(s)

Required to be Aware of .

HASAWA . 1974 – Statutorydocument )
EAWR . 1989 – Statutory document )
BS-7671:2008 / 2011 – Non Statutory document )
O.S.G. – Non Statutorydocument )
Guidance Note 3 – Non Statutory document )
GS-38 – Non Statutory document )

Electrical Installation Certificate .
Certificate is used for ( NewInstallations ) whenever a New circuit has to be Installed . & /or Alternations . Rewiring & anycircuit where the protective device has been changed .
As part of the (Initial Verification ) the date for the next Inspection must be set ( maximum 10 Years for Domestic Installation )

Certification & Reporting

This form must be Accompanied by ( Inspection Schedules& Test Results Schedules )
In the case of ( Consumer’s Unit change only ) Electrical Installation Certificate would be required for the ( Consumer’sUnit ) &
an Electrical Installation Condition Report ( EICR ) should be completed for the ( ExistingInstallation )

Minor Electrical Installations Work Certificate .
□ This one isUsed for work which ( Does ) not involve theInstallation of a ( New Circuit )
□ This Certificateis to be Used when ( Additions to Existing circuitsare carried out ) if .
□ More than Onecircuit is added . Then a separate - Minor Works Certificate . must be issuedfor ( EachModification )

ElectricalInstallations ConditionReport . ( EICR )

Your reasons . for this type of Test are . Wear & Tear . Change of Ownership . Change of Use . Damage to the Property.

Certification & Reporting
This form must be Accompanied by ( InspectionSchedule & Test Results Schedule(s)

□ Diagrams .Charts or Tables should be made available to the person carrying out thisReport .
These Diagrams .Charts or Tables should indicate : Type of circuits & Protective devices .means of Isolation & Switching . methods used for Protect against Fault Protection .

Delegate . will be required to complete the AppropriateDocument during & after the Testing is carried out . ( Starting from . 01.01.2011 . this Documentwill be the ElectricalInstallations ConditionReport . ( EICR )

2392-10 : Weneed to Inspect & Test Electrical Installations to ensure compliance withBS-7671 :2011 .( Non Statutory document )
2392-10 : Bycomplying with BS-7671 :2011 . We arealso complying with HASAWA - 1974 & EAWR - 1989 Both ( Statutorydocument )

 

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-&-s point of View 2392-10 . Insulation Résistance Measurement . (Measurement of Insulation Résistance are to be carried out before the first connection of Main Voltage to the Installation ) …D.C. test voltage .

2392-10 .
Take from BS-7671:2011 . -&-s .

( T ) Which of thefollowing items should be ( Included ) forchecking during the ( Initial Verification ) of an Installation .
Presence of diagrams & Instructions . ( Regulation –611.3. (xvi ) Presence of diagrams . instructions &similar information . p/190

Take from BS-7671:2011 . -&-s .
( T ) One ( Item ) that should be ( Included) on charts & diagrams made ( Available ) tothe person carrying out the ( Inspection & Test ) is .
All Isolation & Switching arrangements ( Regulation – 514.9.1. ( iii ) p/117 .

Take from BS-7671:2011 . -&-s .
( T ) An ( Inspection ) shall be made to ( Verify) that the installed electrical equipment is . NotVisibly Damaged ( Regulation –611.2. ( iii ) p/189 .
( iii ) – Routing of cables in Safe zones . or protection againstmechanical damage . in compliance with Section 522

( T ) Inspection & Testing . Continuity of CPC & Protective Earthing .
( You will use this on .Periodic Inspection & Testing )

p/Regulation 411.3.1.1. of BS-7671:2011 requiresthat Installations which provide protection against Electric Shock using Automatic Disconnectionof supply must have a circuit protective conductor run to & terminated ateach point in the wiring & at each accessory .

 

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you are required to ( Verify the Polarity ) of all circuits before Connection to thesupply . Dead Test . 2392-10 . -&-s

2392-10 . youare expected to Energise the Installation & turning the supply on for thefirst time .


the Regulations don’t tell us about . Live Polarity . “ Testing “ . “ This is a Live Test “

using a ( GS-38 ) approved voltage indicator . you are Testing on the Incoming side of theInstallation . MainSwitch .

Test between ( Line & Neutral )
Test between ( Line & CPC )
Test between ( Neutral & CPC )

After the correct “ Polarity “ has beenconfirmed . Turnthe Main Switch ON if Needed .

One Point I must make . Many Candidates failed to ( Identify the Used ofGS-38 . Test Leads ) ◄◄◄ -&-s Exams .

City & Guilds | 2391-301 Chief Examiners' report ( I wish someone HAD pointed meto the SITE before my 2391-10 ) Happy Hunting . :banghead:

2391-10 : Remember that giving information that is NOT required COSTS the CANDIDATE timebut does NOT ACCUMULATE any MARKS .

 

[amberleaf]

Re: ***Cont../ Useful Information for Electricians’ & Apprentices***

Brianmdk. Thank you for using this Forum . “ As arule you go into the Main Forum Q/As “

“ Old Amber “ . only writes up things for the Forum . . I am sure that Phil or any other Memberwill pick this up .
Has a rule I don’t. do Q/As . I leave that to the Professional Memberson this Forum . I will get in touch with Phil .


Brianmdk. am sure Phil has a ForumE/mail .


I get over 100 E/mail a day . So I limit my time when I can .

 

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Example . -&-s . Correctly indentify the Three documents on which ( Ze) would be recorded .

This is how Ipicked up this . 2392-10 . Look in & start there . p/390 . EIC . ( Ze ) yeah . Minor / No . EICR / yeah . sometime we have to help ourselves .

 

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2392-10 : Check – 530.3.4.which seems to require that the only protective devices specified by themanufacture can be used in a Consumer Unit .

Forinstallations with a 230V single-phase supply rated up to 100A that are underthe control of Ordinary Persons . Switchgear & Controlgear should ether :

-Comply with BS-EN-60439-3 & Regulation 432.1.of BS-7671:2011 .or
-be a Consumer Unit incorporating components complying with BS-EN-60439-3 .

2392-10: Check – 537.1.4.
Amain switch intended for operation by ordinary persons . e.g. of a household orsimilar installation . should interrupt both LiveConductors of a Single-phase supply .

531 . Fault Protection by Automatic Disconnectionof Supply . 2392-10 ( ADS )

531.2. RCD Requirements .–
531.2.1. An RCD shall be capable of disconnecting all ( Line Conductors ) at substantially the ( Same Time )

531.2.5. An RCD cannot be used for ( Fault Protection) on its Own . Where a circuit does “ NOT “ contain a ( Protective Conductor )

2392-10. Does an RCD . NEED an EARTH .

531.2.5. The use of an RCD associated with a circuitnormally expected to have a ( Protective Conductor ) shall NOT beconsidered sufficient for fault protection if there is ( NO such conductor ) even if the rated residual operating current ( IΔn ) of the device not exceed 30mA . … ►► RCD without ( Earth ) N/A

Taking off the Internet . ▼▼▼

RCDdoes NOT necessarily require an Earth connectionitself . ( it monitors only the Line& Neutral ) in addition it detects current flows to Earth even in equipmentwithout an Earth of it Own .

RCD- The amount of current flows through the Line should return through Neutral .
RCD– it Trip the circuit when there is ( Earth Fault Current ) .. Now it takes us back to Regulation ( 531.2.5. ) DO We NEED an Earth

RCD/ RCBO . “ Flying Lead “ has a Functional Earth

 

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UsefulJunk . Example . 4D4B – p/339

1000 . is used in the formulabecause the value from the tables is in millivolts - Convert it to Volts .

Weknow the maximum voltage drop permissible is ( 11.5V) the current in the cable is ( 65A ) & the Length of run is ( 53m )

11.5x 1000 = 11500 .
(65A x 53m ) = 3445 . …………. 11500 ÷ 3445 = 3.33 mV

4D4B – for a Conductor whichhas a voltage drop of ( 3.33 m/V/m ) or less . 16mm[SUP]2 [/SUP]( 2.8 : 2.8 : 2.4 )

Noticethat for ( All ) cables ( Over ) 16mm[SUP]2 [/SUP]there are Threevalues given for voltage drop . ( r . x . & z . )

 

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Requirements. Earthing & Bonding .

Often. there is great confusion over Earthing . Bonding ( Earth Bonding) BS-7671:2011 . requirements forElectrical Installations – “ Defines “

“Earthing “ Connection of the ( Exposed – Conductive – Parts ) of an Installation to the main earthingterminal of that Installation
“ Bonding “ Thecorrect “ title“ is “ p/27 . EquipotentialBonding “ electrical connection maintaining various Equipotential Bonding & ( Exposed – Conductive – Parts ) & ( Extraneous – Conductive – Parts ) at substantiallythe same potential .

►►See also . “ Protective Equipotential Bonding “ p/32. “ Equipotential Bonding “ for the purposes of Safety

(Extraneous – Conductive – Parts ) a “Conductive Part “ . liable to introduce a ( Potential ) generally earth (Potential ) & not forming part of the electrical installation .

(Exposed – Conductive – Parts ) a “Conductive Part “ of equipment which can be touched & which is not a Livepart but which may become Live under fault conditions

Just a Reminder . 411.3.1.2. Protective Equipotential Bonding .
Ineach installation ( Main Protective Bonding Conductor’s ) complying withChapter 54 . shall connect to the ( Main EarthingTerminal ) Extraneous – conductive - Parts . including . ( Water Installation pipes : Gas Installation pipes : Exposed Metallic Structural parts of theBuilding : e.g.

 

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Requirementsof the Earthing System .
Thefunction of the earthing system isTwo-Fold .

□ To provide a low enough impedance path . viathe earth conductors . back to the supply source so that the event of a failureto earth of a live conductor . sufficient current will flow safety along apredetermined route to enable the (Circuit Protective device to operate )

□ To limit the ( Potential rise ) on allMetalwork to which persons & livestock normally have access . To a safevalue under normal & abnormal circuit conditions .
Thebonding together of all normally ( Exposed metalwork ) such . As Gas . Water . etc . & the connection of the ( Bond ) to the Earth Terminal . will prevent thepossibility of a ( Potential difference) arising between adjoining pipework under both normal & abnormalconditions .

Thereare Two main types of Earth Conductors . which are “ Bonding “ referred to as ( Protective ) conductor(s) & Earth Electrodes .
p/23 . Bonding Conductor : A protective conductor providing EquipotentialBonding .
Equipotential Bonding – Main Protective Bonding Conductor .

□The bonding together of all normally ( Exposed Metalwork ) such . As Gas . Water . etc .
p/37 . Main Metallic Water Pipe – ( Extraneous – Conductive – Part - p/28 )

Bonding& Protective Conductors .
Withinthe Regulations . a number of “ Definitions“ you have to describe the differenttypes of earth conductor used .

CircuitProtective Conductor ( CPC )
Thisis a separate conductor installed with each ( Circuit ) & is present toensure that some . or all . of the ( Earth Fault Current ) will flow back tosource along it .
Itmay be an ( Individual ) conductor . the ( Metal Outer Sheath of a Cable ) or ( Metalwork formed by Conduit or Trunking )

p/23 Bonding Conductor(s) . A Protective Conductor providing : Equipotential Bonding – p/37 . MainProtective Bonding Conductor .

Theseensure that ( Exposed – Conductive –Parts ) such as Metal Enclosures . remain at approximately the ( Same Potential) e.g. Under Fault Conditions .
p/27 .Exposed – Conductive – Part . Conductive part of equipment which can betouched & which is not normally live . but which can become live . UnderFault Conditions .
►The two forms of “ Bonding Conductors“

p/37. • EquipotentialBonding is Main Protective Bonding Conductor .
whichinterconnect ( Together ) & to Earth . ( Exposed – Conductive – Parts )which do NOT normally carry current . “ But “ could do so under a FaultCondition .
these( bonds ) normally connect Exposed –Incoming Metal – Gas . & Water pipes……. Main Services . to the ( EarthingSystem )

asit was on the 16[SUP]th[/SUP] Edition . & is still in Use today .
SupplementaryBonding Conductor(s)

Toensure that Electrical Equipment & other items of ( Conductive – Material )in specific ( Zones ) are bonded tighter & remain at ( Substantially the same Potential )
Theyare used in ( Addition to the Main Protective Bonding Conductor . & (Circuit Protective Conductor )

EarthElectrodes . designer . is faced withTwo – Tasks .

□ To ( Achieve ) a required Impedance Value .
□ To ( Ensure ) that “ Touch Voltage “ potentials are satisfactory . 50V .

 

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(TT System ) for most if NOT all of this “ Site “ You do this by NOTusing the DNO – Earth . you provide a ( Rod )
Therisk of Electric Shock is high .
TN-C-Ssystems must not be used forConstruction & Demolition sites Supplies .
TN-C-S supply is provided by the supply provider . ( PS .use your own judgment ) No in the regulations. it may be Converted to a ( TT System this is easily achieved by isolating the supply earth fromthe installation & installing an Earth Electrode for use with an RCD – 500mA

(110V – for all portable ( Tools & Lighting ) 0.2 seconds disconnection for fixedfloodlights ) Table 41.1. 230V – TT – 0.2 seconds.
(230V – Single-phase ) 0.4s & 5s .

TestingEarth Electrode(s) . Pulled out oldNotes . So that got me Started . !! Books are Out .

Ifa 30mA RCD is used . this allows a maximum Electrode Résistance of ( 1.667Ω) although it is recommended that earth electrode résistance should never begreater than ( 200Ω ) A maximum valueof ( 100Ω) is proposed in a draft amendmentof BS-7430 . Code of practice forEarthing .

BS-7430:1991 – which is withdrawn .
Guidanceon the Methods for Earthing Electrical Systems

“ Abstracts “ BSI … BS-7430: 1991 – which is withdrawn.
Givesguidance on the methods that be adopted to ( Earth ) an Electrical System forthe purpose of ( ►► Limiting thePotential ) with respect to General Mass ofEarth . of current – carrying – conductors ( Forming part of the System) & ( Metalwork associated withEquipment . Apparatus . & Appliances connected to the System )

TheElectrical Supply . 16[SUP]th[/SUP] Edition
Thefollowing electrical systems are NOT suitablefor use in hazardous locations .
TN-C.
TN-C-S. ( PME )
InTN-C & TN-C-S - ( PME ) supplies . the Neutral conductor is also the Earthingconductor . Therefore . there could be a ( PotentialDifference ) between the main earthing terminal of the Installation& the General mass of Earth .

This( Standard ) applies ( Only) to land – basedInstallations .

BS-7375:2010 . Distribution on Construction& Demolition Sites . Code of Practice .

Whatkinds of sites are covered by BS-7375 . BS- p/214.

Thesites covered in this standard are areas where any of the following take place.
• Construction work of new buildings
• Repair . alteration . extension . demolitionof existing buildings or part of existing buildings .
• Engineering works .
• Earthworks .
• Work of similar nature .
-This requirements apply to ( Fixed ) or ( Movable Installations )

 

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Updatingof references to BS-7671 . take into account the publication of the seventeenthedition.

704.411.3.1. – Protective measure . Automaticdisconnection of supply .
A( PME ) earthing facility shall NOT be used for the means of earthing for aninstallation falling within the scope of this section ( Unless ) all Extraneous – Conductive – Parts . are reliablyconnected to the main earthing terminal in accordance with Regulation – 411.3.1.2.

Justa Reminder . 411.3.1.2. Protective Equipotential Bonding .
In each installation ( MainProtective Bonding Conductor’s ) complying with Chapter 54 . shall connect tothe ( Main Earthing Terminal ) Extraneous – conductive - Parts . including . ( WaterInstallation pipes : Gas Installationpipes : Exposed Metallic Structuralparts of the Building : e.g.

Thereare differences between BS-7375 & BS-7671 . to do with ( Disconnection Times )
Thereis a large Overlap with BS-7671 . section 704 . different approach in ( BS-7375 ) particularly on the ( 110 volt system) 55 voltsto Earth .

Note . if a ( PME ) Earthing facility is ( Considered) for Use . see also . p/280 - BS-7375:2010 . 704.0./ 704.411.3.1. – Note

(p/54 - Disconnection Times ) 411.3.2.3. in a (TN- system ) a disconnection time Not exceeding ( 5s ) ispermitted for a distribution circuit & for a circuit NOT covered by Regulation . 411.3.2.2.
(p/54 - Disconnection Times ) 411.3.2.4. as Appropriate . in a (TT – System ) a disconnection time Not exceeding( 1s ) is permitted for a distribution circuit& for a circuit NOT covered by Regulation . 411.3.2.2.

( Disconnection Times ) for reduced – Low – voltage –systems in BS-7671 & see if you canfind any ( Equivalent in BS- 7375 )

Classificationof Tools .
Class1 ) tool having at least ( Basic Insulation ) throughout & under certain conditionsrequired to be Earthed . BS-EN.61140. P/287 .
Class11 ) tool with ( Double Insulation ) & / or reinforced insulation throughout& without provision for Earthing . BS-EN.61140.

Class111 ) tool designed for operatingat ( Safety Extra Low Voltage ) BS-EN.61140.
Safety Extra Low Voltage ( SELV ) (- Nominal voltage not Exceeding 50Vbetween conductors . & between conductors & earth . No-load voltagenot ( Exceeding 50V )

704.410.3.10.
Note 1 : The reduced low voltage system is strongly preferred forthe supply to portable hand lamps for general use portable hand tools &local lighting up ( 2kW )
Note 2 : The ( SELV ) system is ( Strongly) preferred for portablehand lamps in ( Confined ) or damp locations .

BS-EN- 60947-2 . MCCBs areadjustable – Thermal & Magnetic tripping characteristics . can be changedon the device . ( normally have to beObtained from the relevant Manufacturer )

RCDsmust conform to ( BS-4293 still on Old Sites )BS-EN- 61008 or 61009 .

OnExisting Installations . ( Integrity ofCables )

 

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p/17. Regulation 131.2.2. 2392-10 .

Goeson to confirm that . in connection with Fault Protection . the application ofthe method of ( ProtectiveEquipotential Bonding ) is ONE of the important Principles for Safety .

 

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Copperhas & continues to be the most widely used material for Earthing .

BS-7430. Code of Practice for Earthing .
Whichstates “ Copper is one of the better & commonly used materials for EarthElectrodes & Underground Conductor’s .

Earthingarrangements’ within buildings in the UK . should conform to BritishStandard – 7671: & 2011.

Forthe sake off . 2391-10 . -&-s Exams . The requirements for “ Erection & Initial Verification of Electrical Installations .

(2 sets of Testing here ) Verification &Periodic Inspection & Testing
i) InitialVerification . 134.2.
ii) Periodic Inspection . 135 . – tofollow 134.2.2.

Appendix 6 . for Certification & Reporting Electrical Installation ConditionReport . that replaces the ( Periodic Inspection Report ) New condition reportincludes a New Inspection Schedule

p/36. Verification : All measures by means of which compliance ofthe Electrical Installation with therelevant requirements of BS-7671 are checked . Comprising
Inspection. Testing & Certification .

134.1.7. Testing – Where necessary for safety purpose. suitable warning signs & / or notices shall be provided .

BS-7671:2011 & GN-3 . go Hand & hand . intesting . & Exams 2391-10 .

313.1. Reminds us . (v) The suitability for the requirements of theinstallation . including the Maximum Demand . 2392-10 .
MaximumDemand . Ring Final Circuit – maximumpermitted sustained load to be drawn by this circuit would . be 32A – 100%

Doesthe device that has to be provided for switching off a bathroom ( Extract Fan ) for mechanical maintenance need to be locatedadjacent to the Fan . ( No )
p/152. Regulation – 537.3.2.4.
Butthe device does need to be placed & marked as to be readily identifiable& convenient for the Intended Use .

2392-10: Installation Circuit Arrangements .

p/46. The Four Regulations under Section 314 of BS-7671:2011 .
Setout the requirements for the circuit arrangements . Essentially . circuits mustbe provided in sufficient number so that danger is prevented . &inconvenience minimised . both under normal & fault conditions &arranged so that operation . Inspection . Maintenance & testing may becarried out in a safe manner .

Itis Important . that a sufficient number of circuits are provided so thatequipment unaffected by a fault condition remains safe & functioning whenanother circuit develops a fault . The designer would need to consider theeffects . in terms of consequential events . of the operation of a singleprotective device .

Regulation314.1.4. calls for each circuit to beelectrical separate & connected individually & detached from all othercircuits where they terminate in a distribution board .
Implicitly: the connection of each circuit Line .Neutral & CPC conductors must follow a logical sequence at theirtermination in the distribution board

Summaryof ( Low
ExistingBS-7671:

 

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Summaryof ( Low – voltage ) fuse standardchanges for first amendment . p/295 .

ExistingBS-7671:2008 fuse. BS-88.2.2. : BS-7671:2011 fuse . BS-88-2 . ( Bolted ) type fuse is recognised ( Fusesystem E )
ExistingBS-7671:2008 fuse. BS-88-6 : BS-7671:2011 fuse . BS-88-2 . “ ( Clip in ) type fuse is recognised ( Fusesystem G )
ExistingBS-7671:2008 fuse. BS-1361 : BS-7671:2011 fuse . BS-88-3 . “ ( Cartridge ) type fuse is recognised ( Fusesystem C )

 

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RCBOs . BS-7671:2008 . Functional Earth Wire Connection Requirement . ??

Eaton– RCBO Functional Earth Wire Connection Requirements ...

 

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Ambient Temperature Correction Factor .

The measured Loop Impedance given . O.S.G. p/120 . Table B8
Thevalues assume that the maximum operating temperature of the insulation is ( 70°C ) & the Ambient Temperature whencarrying out the test is at ( 10°C ) AtAmbient Temperatures other than this . Correction Factors . should be applied .

Table B8 p/120 . The correction factor is given by :
(1 + 0.004 – ambient temp – 10 )
Where( 0.004 ) is the temperature coefficient per ( °C ) at 20°C for copper &aluminium .

If the ambient temp is ( 25°C - 1.06 ) the measured impedance of the circuit protected by a ( 32A type MCB ) should not exceed ( 1.16 x 1.06 = 1.23Ω )

 

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SomethingKnock-up . 2392-10 .

□ Measurementof Prospective Fault Current - Ipf - ( PFC ) & ( PSCC )

For the sake of -&-s )- This test is made with an Earth Fault Loop Impedance Tester set to Amps . -&-s– BS-EN-611557-3.

The ( PFC ) which is how much current will flow in the event of a fault .
isdivided into two parts .

Prospective Earth Fault Current )- Line to Earth .
Prospective Short Circuit Current )- Fault between Liveconductors ! L/N

The ( PFC ) test is made at the Origin of theInstallation . & its value ( Obtained in kA )
(PFC ) & ( PSCC ) tests ( Higher ofthe Two Values is Recoded )

□ How do we Do this Test . for -&-s sake .
BS-EN-611557-3. – GN-3 ◄

AnEarth Fault Loop Impedance Tester .the valueof Earth Fault Loop Impedance ( Zs ) maybe determined by . !!

i) Direct measurement of ( Zs ) at thefurthest point in the circuit .
ii)Direct measurement of ( Ze ) at the Origin of the circuit &adding to the “ Value “ of ( R[SUP]1[/SUP]+ R[SUP]2[/SUP] ) point to NOTE : measured during Continuity Tests .
iii) Obtained the “ Value “ of ( Ze ) from theElectricity Supplier & adding to this “ Value “ of ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) as above .

(Ze ) is the Loop Impedance “ Value “ External to the Source of the Circuit(s) Supply .

 

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□ DirectMeasurement of ( Zs )

Directmeasurement of Earth Fault LoopImpedance . is achieved by use of an . Earth Fault Loop Impedance Tester .
TheInstrument operates from the main supply & therefore can only be used ona ( LiveInstallation ) connected directlyto the ( Furthest Point ) of the circuit .

Note : ( Parallel Paths) will be present which will ( affect ) the true circuit(s) Earth Loop ImpedanceReading(s)

□ Measurementof ( Ze )
(Ze ) can be measured using an . Earth Fault Loop ImpedanceTester . at the ( Origin )
Connectedusing approved leads between the ( Live Terminals ≈ ) ofthe supply & means of Earthing with the main switch closed .

Note : to Remove the possibility of ( Parallel Paths) the means of Earthing must bedisconnected from the Main Protective Bonding . conductors for the duration of the Test.

“ Verification “ of Earth Loop Impedance Test Results .
Valuesof Earth Loop Impedance obtained ( Zs ) should be compared with one of thefollowing . 41.3.: 41.4. : 41.5. :

EarthFault Loop Impedance ( Zs )
• This is a Live Test .
Canbe obtained direct measurement using an “ Earth Loop ImpedanceTester “ Or by adding ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) obtained earlier to ( Ze )

Obtaining( Ze ) External Loop Impedance .
• This is a Live Test .
ByEnquiry ( Must test to ensure Earth ispresent )

Direct measurement of ( Zs ) can only be made on a . Live Installation. No earthing conductors aredisconnected for this purposes of the test & this may result in readingsobtained which are lower than the value of . Ze + ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) This is due to the parallelearth paths presented within the installation .

□ Whattype of Earthing System are there .

Thereare Three types listed in BS-7671:2011 . p/45

TN-S. system
TN-C-S. ( PME ) system .
TT. System .

2392-10: Testing point of View .
Continuity of protective conductors is clearly important as are the Tests for ( Insulation Résistance : Loop Impedance : Operation of RCDs )

 

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Don’t forget “ Lads“ Please show your appreciation with the " THANKS " button !!! :svengo:

 

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(1 ) -

InstantaneousTrip Currents . x In .

MCBs : Icu - ( rated ultimate / breaking capacity )
MCBs : Ics - ( rated service / breaking capacity )

Thedifference between . BS-EN-60898 “ MAY be used insteadof CALCULATION “ / BS-3871 formula. To beUsed :
BS-3871– are still out there .

MiniatureCircuit Breakers “ conforming to BS-EN-60898 are suitable for Isolation ◄
Miniaturecircuit breakers ( MCBs ) manufacturedto earlier standards . such as . BS-3871 : are unlikely to be suitable for Isolation. ◄

Note: There is NO type ( A) instantaneous tripping characteristic to ( Avoidconfusion ) with the ( A ) abbreviation for Amperes . B : C : D : - MCBS

Determinationof Maximum Earth – Loop Impedance ( Zs )
Themaximum value of Earth Fault Loop Impedance maybe found in the . Wiring Regulations . BS-7671:2011 . details’ published bythe Manufactures . ◄◄

 

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B: C : D : - Table 41.3 . BS-EN-60898 . ( For instantaneous operation givingcompliance with the ( 0.4s ) Disconnection time )

B) 3 ( In) to 5 ( In )
C) 5 ( In) to 10 ( In )
D) 10 ( In) to 20 ( In )

B / Curve.
Themain characteristic of the ( B ) curve is Instantaneous trigger for currentsbetween ( 3 to 5 times) the rated current . Therefore .
Theyare mainly applied for the protection of circuits with ( resistive characteristics ) or involvingsignificant cable distance . Incandescent lamps . showers. . etc .

{ B means the fast magnetic trip will operatebetween ( 3 to 5 times ) nominal setting }
p/25 . Circuit Breaker. Abnormal currents such as Short Circuit Currents}

Note : THE valuesspecified in Table 41.3. for the types& ratings of Overcurrent devices listed “ MAY be used insteadof CALCULATION “ p/55 . ◄◄◄◄

Circuitbreakers are going to be used for protection . disconnection times willautomatic conform to the requirements provided that the circuit(s) meet the ( Zs ) …. 41.3.
MCBs. BS-EN -60898 .

TypeB – 3 & 5 times . its rating passed through it .
TypeC – 5 & 10 times .
TypeD – 10 & 20 times .

Tablesfor ( Zs ) specific value of current is required . ( Worst case is Used )

OhmsLaw : to the supply voltage ( 230V ) & ( Ia ) to obtain a ( Zs) value for the device . Regulation411.4.5. – ( Zs x Ia ≤ Uo )

TypeB . – Zs for a 20A can be calculated . 5x 20 = 100 . 230 ÷ 100 = 2.3Ω …… ( Worst case is Used ) ◄◄◄
TypeC . – Zs for a 20A can be calculated . 10 x 20 = 200 . 230 ÷ 200 =1.15Ω
TypeD . – Zs for a 20A can be calculated . 20 x 20 = 400 . 230 ÷ 400 =0.57Ω

□ Switch disconnectors. it function is Only to disconnect electrical circuits with currents of up to 100A . Singlepole . “ Doublepole “ . Triple pole . Four pole .
MainLoad Disconnector Switch – Isolator .

 

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(2 )

TypeB . – Zs for a 20A can be calculated . 5x 20 = 100 . 230 ÷ 100 = 2.3Ω …… ( Worst case is Used ) ◄◄◄

Regulations’. table 41.3 . ( Look it UP )◄◄

Rating20A – Zs . is 2.30Ω .

TypeC . – Zs for a 20A can be calculated . 10 x 20 = 200 . 230 ÷ 200 = 1.15Ω
TypeD . – Zs for a 20A can be calculated . 20 x 20 = 400 . 230 ÷ 400 = 0.57Ω