Re-take - Useful Information for 2394 :

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2394: something for studying .

410.3.2. View to ensuring compliance .
Recognizedprotective-measures . BS-7671:2011:

• Protectionagainst Electric-shock .

ThisChapter - 41 . deals with ( Protection )against electric-shock as applied to electrical-installation(s)

Protective-Measures: 2011:

A protective-measure must consist of provision of Basic-protection. & provision of Fault-protection . Which are Independent .

Independent ) Basic-protection : isprovided by Insulation & Barriers & Enclosures . Consumer-Unit . it’s a start .

Independent ) Fault-protection : isprovided by .
-Protective-earthing ………. ( in case ofFault )
-Protective-equipotential-bonding . ………. ( in case of Fault )
- ( ADS ) Automatic-disconnection of supply . ………. ( in case of Fault )

Basic-protection: is defined as . Protection against electric-shock under . fault-free-conditions . p.51 .
Basic-protection is provided to protect-Person orLivestock . coming into direct-contactwith ( Live-parts )
( Live-parts ) is defined as . p.30 .
Aconductor or conductive-parts intended to be energized in normal-use .including a neutral-conductor but . by convention not a . PEN-conductor .

p.28. Protection under-fault-conditions or ( Fault-protection ) is defined as. Protection against electric-shockunder . single-fault-conditions .

Note : Low-voltage-installation(s) System & Equipment. fault-protection ( generally-corresponds ) to protection againstindirect-contact . mainly with regards to failure of basic-insulation .Indirect-contact is “ Contact of persons or livestock with ( Exposed-conductive-parts ) whichhave become . Live under-fault-conditions “

( Exposed-conductive-parts ) is defended as .
p.27. ( Conductive-part ) of equipment which can be touched & which is not-normally live . but whichcan become . live-under-fault-conditions

( Conductive-parts) which are Accessible . Copper-pipes . Equipment . must not be Hazardous-live . Etc

personcould receive an electric-shock ( Single-fault-conditions ) is in contact with the . Metal-enclosure of an item of . Class-1 equipment which has become .live-under-fault-conditions . thepotential of the Metal-enclosure is higher than that of the .main-earthing-terminal of the installation . & that of a potential-difference created by the passage of ( fault-current ) through the impedance of the .circuit-protective-conductor(s) &the means of Earthing .

Protective-earthing 411.3.1.1.
Requiresall . Exposed-conductive-parts . to be connected to a protective-conductor which in turn isconnected to the ( MET ) if there is anyFault-conditions . Via the Earthing-conductor to the . Means of Earthing .

411.4.4. The following types of Protection-devices maybe used for Fault-protection .
i) . Overcurrent-protective-device .
ii). RCD .
Note 1 : Where an RCDis used for . Fault-protection . the circuit should also incorporate an .Overcurrrent-protective-device .

AProtective-device . maybe . Fuse . Circuit-breaker . RCD . RCBO .

Protective-equipotential-bonding. 411.3.1.2.
Ineach-installation . main-protective-bonding-conductors complying with . Chapter- 54 . are required to connect to the ( MET ) main-earthing-terminal .
Extraneous-conductive-parts such as.
-Water-pipes .
-Gas-installation-pipes .
-Other-installation-pipework . & Ducting
-Central-heating & Air-conditioning -systems .
-Exposed-metallic-structural-parts of thebuilding .

Familiarforms in which RCDs are used to provide . Additional-protection
Wherean RCD is used to provide . Additional-protection . to comply with the requirements ofregulations - 415.1.1. the RCD must have .
i) rated residual-operating-current ( IΔn ) not exceeding 30mA .
ii)Operating-time not exceeding . 40mS at a rated residual-operating-current ( x5 ) as required by theapplicable-standards .

Recognizedprotective-measures . BS-7671:2011:

Protective-measures.

(ADS ) automatic-disconnection .
- Basic-protection provided by - Insulation or Barriers & Enclosures .
Insulation- Basic-insulation of Live-parts . Live-Conductors are usually allocated with this protective-provision .
2394 Consumer-unit : Barriers & Enclosures . Barrier protection form contact with busbar . Your - Enclosure . will be Class - 11 . Ordinary-persons
- Fault-protection provided by - Protective-equipotential-bonding . ( ADS ) Automatic-disconnection .

 

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Pontto Note . “ Private-Landlord “
2394: when to a Job today . Client asked me to change a , Pendent-set . forMetal-light-fitting . after a quick inspection . This was my Reply .

• Warning : You Do not have the provision forEarthing-Metal-Equipment . ( Risk ofElectric-shock )
Donot replace installed-lighting-fittings or switches with . metal-lighting-fitting or switches . ( Sticky-label in my toolbox onto the Consumer-unit )

Hada word with the Client . can fit Class-11 lighting . her reply was what is that . !!! cut to the chase - No-Earthing . Ask the Landlord .

 

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Paul-m . you’re the first person to thank me . Thank-You .
As iv.e had no more thank you.s .

Forth-timearound the circuit . My stuff must be Boring .

 

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Circuit-detail-labels.
Havebeen designed for electricians to leave on . Distribution-boards . when workhas been completed . so that any person wishing to operate . maintain or alteran installation can do so with (Reasonable-safety )

Circuit-details: as we are reminded of . 514.9.1.
-Circuit-number .
-Circuit-designation - for distribution-circuits .
-Type of wiring .
-Reference-methods . see Appendix - 4 . BS-7671:2011:
-Number of points-served .
-Circuit-conductors - CSA - mm[SUP]2[/SUP] . Line . Neutral . CPC . conductors .
-Maximum-disconnection-time . permitted by BS-7671:2011:
-Overcurrent-protective-devices . Type - ( BS-EN - numbers ) . Rating - ( A ) Capacity - ( kA ) RCDs - Operating-current - ( IΔn ) Maximum - ( Ze - Ω ) permitted by
BS-7671:2011:


- - - Updated - - -

2394: I cant stress enough the importance of GN-3 . By its very name . “ Guidance “ What’s in a Book . Answers

GN-3- 2.3. - 514.9.1.

Diagrams. Charts or Tables .

The. Health & Safety at Work Act - 1974. generally requires relevant-information to be available as an . Aid to safe-use. Inspection . Testing. maintenance . This may include those items listed in . Regulation - 514.9.1.

9). The type & composition of circuits . including-points of utilisation .number & size of conductors & type of cable . This should include theinstallation-method shown in . Appendix - 4 . section - 7 . “ Methods of installation “ of BS-7671:2011:

10). The method used for compliance with the requirements for . basic &fault-protection & . where appropriate . the conditions required for ( ADS) - 410.3.2.
11). The information necessary for the identificationof each-device performing the . functions of protection . isolation &switching . & its location .
12). Any circuit or equipment . vulnerable to a particular-test.

Regulations . A -legible-diagram . Chart or Table orequivalent form of information shall be provided indicating in .

514.9.1. just a reminder .

i) - Type & composition of ( Each-circuit points of utilisation served ) number &size of conductors . type of wiring .
ii) - Method used for . compliance with regulation . 410.3.2.
iii) - Information-necessary for the ( Identification of each-device ) the functions of ( Protection )
iv) - Any circuit or equipment ( Vulnerable to a typical-test )

Regulationsreminds us . for simple-installation(s) the . foregoing information may be given in a ( Schedule)
Adurable-copy of the ( Schedule ) relating to a . distribution-board shall be provided within or adjacentto ( Each distribution-board ) Etc .

Circuit-detail-labels. if we look on the Internet . theselabels will fall in to the category of. 514.9.1.

514.9.1. - ( Identification of a Protective-device )
Protective-device shall be arranged & indentified so thatthe circuit-protected may be easily indentified . Diagrams & Documentation .

Legible-diagram. Chart or Table or equivalent form ofinformation shall be provided indicating in
i) - Type & composition of ( Each-circuit points of utilisation served ) number &size of conductors . type of wiring .

inAddition ( Each-circuit -breaker ) needs to be marked-up to show its function .- refer 514.8.1.
514.8.1: A . protective-device shall bearranged & indentified so that the . Circuit-protected may beeasily-recognized


Somethingto think about .

Myunderstanding is that your . Schedule ofTest-results . will suffice as a ( Circuit-Schedule ) Your leaving a copy of the Certificate there .
Put !! ) The fact of the matter . Schedule ofTest-results . it on the Certificate already is beside the point. This Certificate may not be Availableto the next-person for information available .

( He who never made mistakes never made “ Anything “ )

Circuit-detail-labels. it’s a start .

Havebeen designed for electricians to leave on . Distribution-boards . when workhas been completed . so that any person wishing to operate . maintain or alteran installation can do so with (Reasonable-safety )

Circuit-details: as we are reminded of . 514.9.1.
-Circuit-number .
-Circuit-designation - for distribution-circuits .
-Type of wiring .
-Reference-methods . see Appendix - 4 .BS-7671:2011:
-Number of points-served .
-Circuit-conductors - CSA - mm[SUP]2[/SUP] . Line . Neutral . CPC . conductors .
-Maximum-disconnection-time . permitted by BS-7671:2011:
-Overcurrent-protective-devices . Type - ( BS-EN - numbers ) . Rating - ( A ) Capacity - ( kA ) RCDs - Operating-current - ( IΔn ) Maximum - ( Ze - Ω ) permitted by
BS-7671:2011:

 

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( Circuit-loop-impedance )
Earth-fault-loop-impedance. ( Zs ) is an essential-factor . where the most commonly used .Protective-measure - ( ADS )

Fault-conditions Line to Earth-fault . T&E . 2.5mm[SUP]2 [/SUP] . in this case . Circuit-loop-impedance . Line -R[SUP]1[/SUP] & Circuit-protective-conductor R[SUP]2[/SUP] . CPC

p.39. Formula for . Earth-fault-loop-impedance . Zs = Ze + ( R[SUP]1[/SUP]+ R [SUP]2[/SUP] ) ohms

( R[SUP]1[/SUP]+ R [SUP]2[/SUP] ) 2394 : Testing - Ω . Schedule of Test-results .
R [SUP]2[/SUP]) regulation reminds us . ( CPC ) of a distribution . orFinal-circuit . 2394 : but in our case .at the Consumer-unit .

 

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2394: Your making an Assessment of ( PFC ) Protective-fault-current . ( PSCC ) & ( PEFC ) 612.11.

 

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Useful-junk .

What is ( PSCC ) &why is Loop-résistance important .

By using . Ohms-law . the Loop-résistance will - determine the maximum-current that can flow around a circuit .
Example - Loop-resistance !! . 1Ω . & the supply-voltage . 230V

Voltage / résistance = current . ( 230V ÷ 1Ω = 230Amp ) themaximum-current that could flow would 230A .
If we think about . fault-conditions . ?? . soif we had an Appliance that was “ Dead-short-circuit “ as wecan see a circuit-breaker (Protective-device - 32A )
Protective-device ( 32A ) . is lower than ( 230A )

 

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Rule of thumb . Appendix - 4 . BS-7671:2011:

Circuit has a measured ( Zs ) of 0.51Ω - (Your Measured Value is 0.51Ω )
Protected by . Type C - 32A . BS-EN-60898 . MCB

Table 41.3. Maximum permissible ( Zs ) C - 32A . 0.72Ω
Multiply the maximum permissible value by .( 0.8 ) : 0.72 x0.8 = 0.57Ω . This now becomes the . maximum permissible value .
The measured-value is less than this . ( 0.57Ω less than 0.72Ω ) the circuitPassed .

 

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2394 : this isall you have to know . at this Mo .

( Circuit-loop-impedance ) Thisis a Live-Test .

Method of earth-fault-loop-impedance - ( Zs ) testing at . socket-outlet . ( Circuit ) total-earth-fault-loop-impedance can be Measured by ( plugging a ) . earth-fault-loop-impedance-tester. into Socket-outlet

-&-s . BS-EN-61557-3 . - Earth-fault-loop-impedance-tester .

With the same Tester . GN-3 . p.83
These-instruments may also offer additional-facilitiesfor deriving . Prospective-fault-current . ( PFC )

 

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2394 : Question . Why “ Dead-Tests “

Firstly : performed on an Installation - prior to Energisation .

“ Dead-Tests “ will . if carried-out correctly .Indentify-faults . within any Circuit .

610.1. Every-installation shall . during erection & on-completion ( before being putinto service ) be Inspected &Tested . to verify . so far is reasonably-practicable . that the requirementsof the regulations have been met .

 

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2394: Studying is the part of understanding .

O.S.G.- p.18 . Domestic whereUnskilled-persons have access for there Use . Class - 11 . Enclosure .
Asthe regulations rightly put it . Under the control of Ordinary-persons .

Consumer’sControlgear .

Consumer-Unit. to BS-EN-60439-3 . Annex ZA . is foruse on single-phase-installations up to 100A . may include thefollowing-components . 530.3.4.
- Double-pole-insulator.
-Circuit-breakers . or RCBOs for protection against . Overload &Fault-currents .
-RCDs for additional-protection against Electric-shock .
-RCDs for . Fault-protection .

Containing. Protective-devices .
AnnexZA . ( Informative) 530.3.4.

Split-load “ Example .

100A- Double-pole ◄► ( A ) circuit . & Two-RCBOs - circuit 1 . 2 . 3 - spare / way

RCD- 30mA ◄► ( B ) circuit . 6 -Way . - circuit . 4 . 5 . 6 . 7. 8 . 9 - spare / way
RCD- 30mA ◄► ( C ) circuit . 6 -Way . - circuit 10 . 11 . 12 . 13 . 14 . 15 - spare / way

 

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Formy old notes . Useful-junk .

Circuit-breaker.
Instantaneous-trippingwill occur within . 0.1s . within the range of currents which are multiples ofthe nominal-rating of the device ( In )
16A- type B . will disconnect a fault in . 0.1s . when the . Fault-current is in the range of . ( 3 x 16 = 48A . 5 x 16A = 80A ) .

Instantaneous-tripping- ( In - 3x )
In ) rated-current or current-setting of . protective-device .

Circuit-breaker. a device-designed to open & closea circuit by . No-automatic-means .&to open automatically on a predetermined-overcurrent .

 

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RCDtest-instrument needs to supply a range of Test-currents appropriate to thedevice being tested & display the time-takenfor the device to operate .
p.84. GN-3 . reminds us . To check RCD operation & to minimise danger during the test . thetest-current should be applied for no longer than . ( 2s)

Not in . GN-3 or Regulations .
Oneof the principal-requirements is that under any-circumstances the duration of the . Test-current . cannot exceed ( 2s ) this makes it possible to test most ( Time-delay-devices ) which have been installed to . ensure-discrimination. between RCDs of different-operating-currents

The. Test-current . for a full ( 2s ) without the RCD operating .
Ifthe device should trip it is possible that there could be . nuisance-tripping

Third-testto be carried out to the RCD x5-time . rated at no more than 30mA for these devices we must carry out a test at. five-time ( x5) the rated current .so our 30mA device this will be at 150mA . when this test is appliedthe device should operate within a time of . 40mS . that is - 0.04s . ( 5 x 30 = 150mA )

30mA/ 100mA . Discrimination
Discriminationbetween RCDs is archived by using a . time-delay . This allows . sufficient-time for the RCD .protecting the final-circuit todisconnect the circuit . before the main-RCD operates . speed of operation has to be . 0.04s - with five-times therated-tripping-current . ( 5 x 30 = 150mA )

 

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UsefulJunk .

2394: Lets go back to Basics . for the sakeBS-7671:2011: RCD - mA . What’sin a amperes ( A )
30mA- IΔn ) is the rated-residual-operating-current ofthe RCD . so if we take it in Amps - 0.03A

Milli : divideby 1000 . 30mA = RCD - 30 ÷ 1000 = 0.03A . amperes

100mA ÷ 1000 = 0.1A
300mA ÷ 1000 = 0.3A
500mA ÷ 1000 = 0.5A

 

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Characteristicsof protective-device - BS-EN-60898 & BS-EN-61009-1 . Overcurrent-protective-devices to comply with .
Three-tripping-characteristic B . C . D .
Tripping-characteristic → ( Btype ) Etc .

32A . BS-EN-60898 - B type .

Measured-value is 0.93Ω . Atthis stage you have only measured . ( itis Not the Maximum- Zs )
2394 . As the regulation tells us . Zs at 70°C - Maximum . forthe circuit . PVC - T&E . 32A / 1.44Ω .

Current-carrying-capacity . Table-4D5 .
Themaximum-current which can be carried by a conductor under-specified-conditions. without its steady-state-temperature . exceeding a specified-value .

Firstly: 70°C - thermoplastic-insulated & Sheathed-flat-cables . T&E . with -protective-conductor - Copper-conductor(s)
Ambient-temperature- 30°C
Conductor-operating-temperature - 70°C

So no calculations are needed . in this case .


Loop-impedance. Of the cable limits the electricity during a fault .

Maximum ( PSCC ) at thesupply-terminals has been quoted by . DNO as 16kA .
External( Ze ) can be calculated by . Uo /If . 230V ÷ 16000 - ( If ) = 0.014375 Ω . rounded up . 0.0144Ω

Providedby the DNO. Maximum-fault-levelat ( Point ) itis Known .

BS-EN-60898 . in our case . Circuit-breaker . 6kA . 230 ÷ 6000 = If . ???

Point to note . p.55. Circuit-breakers.
Thevalues specified in .Table - 41.3. for the types & ratings ofovercurrent-devices listed may be used instead of calculation . ◄◄

Circuit-breakerare sized to protect the integrity of the cable-insulation .

BS-EN-60898.
Circuit-breakers- for Overcurrent-protection for household & similar-installations

differencebetween the Two-short-circuit-ratings. ( Icn ) & ( Ics - Short-circuit-current at theOrigin ) of the circuit .

GN-3. p.56 . “ the two must not be confused “
(Icn ) is the maximum-fault-current thedevice can . interrupt-safely . although it may no longer be usable .
(Ics - A ) is the . maximum- fault-current the devicecan interrupt-safely without-loss of performance .

Two-short-circuit-capacity-ratings- are defined in . BS-EN-60898 & BS-EN-61009-1 .

Current-carrying-capacity . Table-4D5 .
Themaximum-current which can be carried by a conductor under-specified-conditions. without its steady-state-temperature . exceeding a specified-value .

 

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Ido feel these a need to harp on about . Circuit-breakers . so am on rant - mode .

32A- Circuit-breaker BS-EN-60898 - B . valueof ( Zs - 0.98Ω - your measured-value ) . 5 x32A = 160A . 230V ÷ 160 = 1.4375Ω .
5x 32A - ( If ) fault-current = 160A . fig.3.4. reminds us that . Prospective-current - rms . Amperes

2394: Table - 41.3. . Example . in our case here . ( Zs -circuit-loop-impedance ) 32A / Zs . 1.44Ω :
Zs ≤ 230V ÷ 160A = 1.4375Ω . lets round it up . 1.44Ω . making me . Maximum- earth-fault-loop-impedance . ( Ief )

Line-conductor - Protective-earth ( PE ) T&E
Fault-loop- determination of measurement . ( Circuit-loop ) Ring-final-circuit . Radial-circuit .or final-circuit.
Impedance- Verification . Fault-loop-impedance . in or case . ( Zs ) Earth-fault-loop-impedance . ( 2394 : Circuit-loop-impedance Ω )


-&-s- question(s) . whether you canunderstand & calculate the . ?? following-procedure .
calculatethe . Design-current . for each-circuit . PS in this case a Cooker .

Ib = P/V
Ib = 14000 / 230V .
-&-s- ( Ib ) = 10A + 30% ofthe remainder . + 5A for the socket .
Ib= 29.5A

Pointto note : O.S.G. - p.176
Cooker-circuitsin household & similar-premises .
Therating of the circuit is determined by the . assessment of the current-demandof cooking-appliance(s) & cooker-control-unit-socket-outlet . if any . inaccordance with . Table-A1 of appendix - A
A - 30 or 32A circuit is usually appropriate . for household orsimilar-cookers . ( Of rating up to - 15kW )

 

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Thankyou Dan / Jason

Thereare many Electrician’s that are Unemployed . firstly . Data-Protection-Act .


Brilliantletter to withhold or withhold consent .

Thenyou need to Protect YOUR PersonalInformation!

Job-centre-plus. What do I have to consent TO

-Privacy .
-Personal-information
-Jobseeker - agreement
-What do I have to disclosure

-a friend of mine . was asked to give out . his Email address . ( Data-Protection-Act . N/A ) his contact numbers N/A

Iwent through the Internet for him .

Pleaseread up on matters concerning the somefacts . Don’t be Bulled

[h=3]|Consent | Welfare to Work(fare) Programmes | DWP Jobcentre ...[/h]www.consent.me.uk/

 

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Themost effective way of testing for . Earth-faults in wiring or equipment is by measuring the ( Insulation-résistance) 612.3.1.
The Insulation-résistance . shall be ( Measured ) between Live-conductors & betweenLive-conductors & the Protective-conductor connected to theEarthing-arrangement . Where appropriate during this ( Measurement ) Line &Neutral-conductors may be connected together .

 

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Nails& picture hooks . screws & power-drills . a floorboard nail drivenbetween the neutral & earth fault which is likely to cause an upstream RCDto trip . The fault can be located by ( Insulation-résistance) testing . The damaged cable must be replaced & either relocated to avidfurther damage or protected . Requirements to protect cables from impact &penetration are in . regulation - 522.6.101.
(iv)B mechanically protected against damage sufficient to prevent penetration ofthe cable by nails . screws & the like .

 

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Moisture-ingress. can cause reduced ( Insulation-resistance ) resulting in ( RCD . RCBOs . MCBs )operation . Reduced-insulation . can result from ( Wet-plaster ) condensation or water entry into accessories. Similarly some appliances may exhibit reduce-insulation causingoperation
Certain . installed servicesas heating-elements in Cookers can have reducedinsulation when Cold . the insulationincreasing when Hot .
Manufactures instructionsshould be consulted .

 

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Past to Present

Loose-connections .

a loose connection downstream of an RCD . may causeit to operate due to transient-voltages or capacitive-effects . Everyconnection must be properly constructed .
Regulation – 133-01-04 : ofdurable electrical continuity & adequate mechanical strength - 526-01-01 . correctly selected - 526-02 . enclosed - 526-03 . & accessible . where required - 526-04 .

Regulation - 133-01-04 :
Every electrical-joint & connection shall be of proper construction asregards conductance . insulation .mechanical strength & protection .

Regulation - 134.1.4. :
Every electrical-joint & connection shall be of proper construction asregards conductance . insulation . mechanicalstrength & protection .

Regulation - 526-01-01:
526-01 :Connections between conductors & between a conductor & equipment .
526-01-01 : Every connections between conductors &between a conductor & equipment shall provide durable electrical-continuity& adequate mechanical strength ( see Other mechanical stresses . Regulation- 522-08: Other Mechanical Stresses ( A-J )

526 : Electrical Connections .
526.1. : Every connections between conductors& between a conductor & equipment shall provide durableelectrical-continuity & adequate mechanical strength protection
Regulation - 522.8 : Other Mechanical Stresses ( A-J )

 

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by Verification . Part-6 of BS-EN-61557 .

BS-EN-61557-6 . has requirements for the following( Tests ) to be applied to RCDs .

- Non-tripping ( 50% ) test . 15mA / 30mA
- Tripping ( 100% ) test .
- 5 IΔn ( 500% ) test . - ( 5 x ) X is your multiplier . 5 x 30mA = 150mA .

 

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17[SUP]th[/SUP] Edition . requirements for Testingof RCDs . Has .
The following requirements in ( Terms ) of ( Verificationof Installed-RCDs )

612.8.1. Requires the . Effectiveness of ( ADS ) of supply . by RCD to be Verifiedusing ( Test-equipment ) meeting the requirements of ( BS-EN-61557-6 ) .

 

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Tripping-Current-Test : The .

Purpose of this test is to ( Confirm ) thatthe residual-operating-current . of the protective-device is less-or-equal tothe rated residual-operating-current . This.
Is a ( Measure ) of the continued effectiveness ofthe ( Device ) to work as required by . BS-7671:2011: & in accordance withits ( Product-specification ) when installed for the ( Purpose of providing )ADS . in the event of a fault . it .
Does ( Not - demonstrate ) its Suitability in terms of providing .Additional-protection . ( The Test ) should be performed in both the
i) . Positive .
ii) . Negative - half-cycles .

 

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Earth-fault-loop-impedance . ( Zs )
is a . Characteristic-vital to the . protection-measure( ADS ) Automatic-disconnection ofsupply . which is used for . fault-protection .

Requirements for . Earth-Fault-Loop-Impedance . tobe ( determined )
External )earth-fault-loop-impedance ( Ze ) is one of the . Characteristic of the supplyto an installation . that have to be ( determined ) in order to meet the requirements of -Regulation - 313.1 . BS-7671:2011:

Three-Methods of determining- ( Ze )
- Calculation .
- Enquiry .
- Measurement. 2394 : in our case . “ At the Origin “

Earth-Fault-Loop-Impedance . ( Zs ) “ Circuit-loop-impedance “
Regulation - 612.9. requires that . where .protective-measures are used which require a Knowledge of the .earth-fault-loop-impedance ( Zs ) the relevant-impedances are to be
- Measured .
- Determined by an alternative-method .

- Measurement of ( Ze ) gives the present-value .
Not the “Normal-range “ of values of ( Ze ) in order to . determine the “ Normal-range“ of values of ( Ze ) also necessary touse Information-obtained either by
- Enquiry
- Calculation

- Enquiry . - ( DOES) not
- Calculation - ( DOES ) not
( DOES ) not verifythat the . intended-means of earthing is ( Present) or that the value of ( Ze ) is withinthe . expected-normal-range .

 

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Usefuljunk - Crimp-Lugs .

Maximum. Elec-rating .

10mm[SUP]2 [/SUP] - 62 amp .
16mm[SUP]2 [/SUP] - 88 amp .
25mm[SUP]2 [/SUP] - 115 amp .
35mm[SUP]2 [/SUP] - 160 amp .
50mm[SUP]2 [/SUP] - 215 amp .
70mm[SUP]2 [/SUP] - 235 amp .
90mm[SUP]2 [/SUP] - 255 amp .

 

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Typical causes of Unwanted-Tripping . RCD(s)

- Loose-connections .
- Incorrect-applications . ( Correctly located interminals & tight - correct polarity )
- Wet-plaster / Condensation .
- Moisture-ingress . Appliances . sockets .
- No-discrimination between RCDs .
- Cross-neutral on Split-Loads .
- Neutral to Earth-fault .
• Householder - DIY . faults .Nails / picture-hooks . ( Cutting through a cable )
• Faults on the wiring areoften caused by . Nails or Screws driven between the ( Neutral &Earth-conductors ) “ Common “
- Heating-elements - Cooker . ( Leakage-current )
- Reversed Neutral & Earth-connections .
- Neutral-conductor touching anEarthed-mounting-box .

 

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Certification & Reporting .

( r[SUP]1[/SUP] . r[SUP]n [/SUP] . r[SUP]2 [/SUP] ) youhave confirmed . Continuity . & Polarity . by “ Continuity-method “

Schedule of Test-Results .
The . Schedule reminds us .Ring-final-circuit-continuity ( Ω ). ( r[SUP]1[/SUP] . r[SUP]n [/SUP] . r[SUP]2 [/SUP] ) Little - r/s . 10 . 11 . 12 .

( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) do we need a reason .
( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) is for initiallyverifying that both the Line-conductor & Circuit-protective-conductor . arepresent at points of any Utilisation .

Testing ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) Radial-circuit . the measurement can bedetermined by testing across . Line & Circuit-protective-conductor - ( CPC)

 

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Useful junk . What is Part - 1 .

This is in BS-7671:2011: p.34 . “ Definitions “ RCCB. RCBO. “

Guide to Low-voltageresidual-current-operated-circuit-breaker
BS-EN-61008-1 . RCCBs - Part-1 . general-rules
( General-rules )Residual-current-operated-circuit-breakers ( Without )Integral-Overcurrent-Protection for household & similar uses .
Not-designed to performthe functions of protection against . Overload or Short-circuit .

Guide to Low-voltage circuit-breaker-standards .
BS-EN-61009-1 . RCBOs - Part-1 . General-rules
( General-rules ) Residual-current-operated-circuit-breakers. ( With ) Integral-Overcurrent-Protection forhousehold & similar uses . designed to perform the functions of protection against . Overloador Short-circuit .

 

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Simple things we take for granted
Probe-contact-résistance . when we are testing . ( Pressure-applied ) it’sall in the Contact .

Crocodile-clips . when attaching the clips for ( Nulling & Measurement )

 

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p.28 . Extraneous-conductive-parts .
Conductive-Parts : ≈ .
- Liable tointroduce a potential .generally .Earth-potential .
- Not . forming-part of the Installation .

 

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p.34 . Simultaneously-accessible-parts :
- Conductors or Conductive-parts .
Which can be ( Touched-simultaneously )
- by a person or . locations specifically intendedfor them . by Livestock .

 

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2394: Do we need reasons :
“ Confirming“ Where the supply is provided with an Earth-Connection from the DNO .Distribution-Network-Operator .
- Intended means of Earthing is defective .
- Even non-existent .
Reason : ( Ze ) by measurement also verifies the intended means of Earthingis Present .

 

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-&-s : State . Verification of Polarity . ( Accessories )
( Accessories ) bydefinitions p.23 .
A device . other than current-using-equipment . (Associated with such equipment ) or with the Wiring of an Installation .

 

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Installation can be (Any ) abbr : Installation
p.27: Electrical-Installation- “ Assembly of associatedelectrical-equipment having co-ordinated characteristics to fulfil aSpecific-purpose “

 

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Direct measurement of ( Zs )
Q) . What is direct measurement ? A) . Direct-measurement ofEarth-fault-loop-impedance is achieved by use of an Earth-loop-impedance-tester.
This Instrument operates from the ( Main-supply ) making ita Live-Test .

- Instrument is fitted with a standard-13A plug.for connecting to the Installation directly through a normal-socket-outlet .

 

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Thisbring home how Important it is to Test.

Zs. ( Accessory ) Socket-outlet(s) perform the test on the Outlet which is furthest fromthe Origin of the circuit .
Not-known !! . Test all . Socket-outlets inthe circuit & record thehighest-value .

 

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State Three -documents on which the value of prospective fault current should be recorded .- at this point . look in page 391 . 397 .

( EIC ) - p.391 . Nature of Supply Parameters. Prospective fault current ( Ipf ) . “ 1.17 - kA “
Note - (2) . by enquiry or . by Measurement .

( EICR ) p.396 . Nature of Supply Parameters .Prospective fault current ( Ipf ) .
Note - (2) . by enquiry or . by Measurement .

GN-3 : p.57 .
Recording the Prospective fault Current . ( Ipf)
Both the ( EIC ) & the ( EICR ) contains a boxheaded . Nature of Supply Parameters , which requires the ( PFC ) at the origin to be recorded
This value to be recorded is the greater of etherthe . Short-circuit current ( Between live conductor ) or the Earth-faultcurrent ( between line conductor(s)& the main-earthing-terminal )

If it isconsidered necessary to record values at other relevant points , the can berecorded on the . Schedule of Test Results
Where . the protective-devices used at the originhave the necessary rated breaking capacity . & devices with similarbreaking capacity are used throughout the installation . it can be assumed thatthe Regulations are satisfied in this respect for all distribution boards .

 

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Two-methods for measuring RCDs .

BS-EN-61557-6 . fitted with a ( standard-13A plug-top) by plugging the instrument into asuitable-socket-outlet . protected by the RCD under test.
(Appliances should be disconnected prior to Testing )

BS-EN-61557-6 . Tests are made on the ( Load-side ) of the RCDbetween the Line-conductor of the protected-circuit & the associated ( CPC) Circuit-protective-conductor

RCD-test-instrument(s)require a few . milliamperes to operate . this is obtained from the Line &Neutral of the circuit under-test .

 

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Verificationof Test-results . 2394 :

Scheduleof Test-results : is a ( Written-record ) of the results obtained when carrying out theTests required by . Part-6 of BS-7671:2011: