Re-take - Useful Information for 2394 :

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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 .