Re-take - Useful Information for 2394 :

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Blastfrom the Past . still out there . Yeah

Measurementof ( Ze ) Three-phase .

Older-method: ( Fuses )Still out there .
Fuse(s)must be .( removed ) to disconnect theInstallation for this test .
Live-test . Red .Yellow . Blue . ( Old-colourswill be still in Use )

Three-probes
1). Probes on disconnected - Earthing-conductor
2). Probes on Neutral .
3). Probe on Line . Red . Yellow . Blue .
Red- 0.25Ω .
Yellow- 0.26Ω .
Blue- 0.25Ω .

 

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Useful junk

Determine of 3phase - fault-current .

Highest . single-phase value measured . = 2.28kA .( 2.28 x √ 3 = 3.95kA )
An . approximation can be done as ( 2 x ) the reading . i.e. ( 2 x 2.28 =4.56kA )

Minimum breaking capacity for protectivedevices kA

 

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( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) are the effective-résistances . to thefurthest-point
( 1.67 - relates to the ratio of résistance of . ( 2.5mm[SUP]2[/SUP] / 1.5mm[SUP]2 [/SUP] ) it won’twork for ( Other-sizes ) Ring-final-circuit Only .

( Zs ) Confirms that a (Satisfactorily-low-fault-path-exists ) to activate the . relevantprotective-devices .

 

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UsefulJunk .

Nuisance-Tripping.
Certain-appliancessuch as Freezers tend to have . bynature of there construction & use . some leakage-currents to earth .

 

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433.1.103. - Ring-final-circuit(s) p.81.
MinimumC.S.A. of PVC-cables . 2.5mm[SUP]2[/SUP]
MinimumC.S.A. of ( MI ) cables . 1.5mm[SUP]2[/SUP]
Minimum-current-carrying-capacityof . Line & Neutral-conductor(s) - ( Iz) 20A - device . 433.1.1
Theload-current should not-exceed what for . long-periods . Current-carrying-capacity of the cable ( Iz ) of the cable .
British-standardsof . accessories to be . BS-1363 .
Overcurrent-device to be rated at . 30A or 32A . protective-device .

 

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Residual-current - Making me . ( dual-current )

TheRCD is designed to trip out when the difference between the . Line-current andthe Neutral-current ( So this is called the . residual-current) reaches the tripping-value . ( or rating ) of the device .
- Sensitivity: IΔn

RCD- Sensitivity is expressed as the rated-residual-operating-current ( IΔn ) .

TheTerm . RCD . is a generic-term applied . which open automatically in response toa . residual-current . equal to or greater than the RCDs - rated-residual-operating-current ( IΔn )

 

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RCDsfall into two-categories in term of the time taken to respond . BS-EN -

(G ) General-type . These RCDs have no specified-minimum-response-time . but have specified . Maximum-response-times.
IΔn ≤ 300mS
5x IΔn ≤ 40mS .

(S ) Type : Known as . delayed-types . specified . Minimum and Maximum-response-times .
IΔn ≤ 130- 500mS
5x IΔn ≤ 150mS

 

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RCDmaximum ( Zs- Ω ) or ( R[SUP]A[/SUP] - Ω )values .
IΔn- ( A ) maximum-touch-voltage - ( 50V )

30mA ) 0.03A - 1667Ω .
100mA ) . 0.1A - 500Ω .
300mA ) . 0.3A - 167Ω .
500mA ) . 0.5A - 100Ω .

- R[SUP]A [/SUP]≤ 50V ÷ 0.03A = 1667Ω . IΔn - 30mA
- R[SUP]A [/SUP]≤ 50V ÷ 0.3A = 167Ω . IΔn - 300mA

 

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Test-procedure: your reason .
Theobject of continuity-testing . is to measure only the résistance of the partsof the wiring-system under test . T&E .

Whatis . Earth-fault-loop-impedance .

The path followed by . fault-current as a result of alow-impedance fault occurring between the . Line-conductor and Earth . & Earth-fault-loop . Fault-current is driven round the loop by thesupply-voltage . the amount of currentdepending on the voltage of the supply and on the impedance of the loop . The higher the impedance . the lower will be thefault-current . and the longer it will take for the circuit-protective-device operate and interrupt the fault . Loop-impedance must be low . to ensure that circuit-breakers will operatequickly enough in the event of a fault . The actual maximum-value depending on the . characteristics of the . circuit-breaker concerned . 2394: Testing of - Circuit(s) must be tested to make sure that the actual . loop-impedance does notexceed that specified for the protective-device ( Circuit-loop-impedance )

 

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Whytwo -RCDs . split-load .2394 :

The circuits need to be divided evenly between two-RCDs to ensure some . lighting & power remainsif one operates .
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RCD- ( G ) general-use . for Instantaneous

 

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IEC-479-1 :

A residual-current-device . will ( Reduce ) the risk of Electric-shock .

Providedit has a residual-operating-current . not exceeding 30mA. & an operating-time not exceeding. 40mS . when a residual-current of 150mA - flows .
Thesecharacteristics are derived from the graph-shown . effects of current on thehuman-body can tolerate verysmall-currents for reasonably-long-periods . & moderate-currents forvery-short-periods .

Conductor(s): résistance .
Theease by which a . material-conducts electricity . is known as - résistance .

Conductor(s)- Interpreting .

Neutral-conductor. is defined as a . Live-conductor .
p.31: Neutral-conductor - A conductor connected to the . neutral-point of a system .& ( Contributing ) tothe transmission of ( Electrical-energy )

p.30: definition of - Live-conductor . refersto the . definition for . Live-parts .
Live-parts- a conductor or conductive-part intended to be . energized innormal-use . ( Including ) a neutral-conductor . Etc . This confirms that the . Line &Neutral-conductors . are both . Live-conductor(s) when energised .

(G ) RCD - device . as the earth-fault-current - ( If ) is . likely to be much higher than the . IΔn settings of the device installed . 30mA ÷ 1000 = 0.03A .

 

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2394:
Circuit-breakers. ( is both a Circuit-breaking-device ) Emergency / switching . Table - 53.4.

Overcurrents- are detected by . three-different-devices .
-Thermal for Overloads .
-Magnetic releases . which aregenerally-combined - ( Thermal / Magnetic-circuit-breakers )

2394: Very basics . BS-EN-60898 - Manual or Automatic-control - of acircuit .

Circuit-breakersare identified with . Two-breaking-capacities .

6kA )- . BS-EN-60898- standard for household or similar-applications. where Unqualified-persons. can re-closes a circuit with a persistent fault-several-times . the breaking-capacity - in Amps .
p.285 . BS-EN-60898- 1 .Specification for circuit-breakers for . Overcurrent-protection . for household & similar-installations.

p.286. BS-EN-60947-2 . Circuit-breakers 10kA . Qualified-persons .

p.149. Circuit-breakers : Table-53.4.
BS-EN-60898 .
BS-EN-60947-2.
BS-EN-61009-1.

Donot get mix up .

BS-EN-60947 . Low-voltage . switchgear & control-gear .

BS-EN-60947-2. Circuit-breakers - 2006 .

 

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Table- 41.2. : 41.4 : Type of fuses .
Fusesare indentified by . 2 - letters . according to their application-category . in ( LV-installation )

Thefirst-letter . indicates the . main-operation . ( g ) = general .
Thesecond-letter . indicates the . categoryof equipment to be protected .
G) protection of cables & conductors.
M) protection of . motor-circuits .
(gG ) - ( gM )

 

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DNO: It is noted that .Supply-cut-out-fuses . are allowed to be utilized for overload-protection . ofthe main-supply-cables - 433.3.1.


Note : we are using thecircuit-breaker-side BS-EN-61009-1 .
Note : Regulations - 41.3. BS-EN-60898 & BS-EN-61009-1 .
Maximum-earth-fault-loop-impedance. ( Zs ) for circuit-breakers with . Uoof 230V . for . ( Instantaneous-operation ) Etc .

Domestic-installationsthe . ( PFC ) is unlikely to exceed . 6kA . up to which value the . [ Icn ] & [ Ics ] valuesare the same .
PlainEnglish - Note . Two-rated-short-circuit-ratings. protective-devices . BS-EN-60898 & BS-EN-61009-1 .

GN-3: p.100 - reminds us . Generic Scheduleof Test Results .
3). BS ( EN ) enter the . standard of manufacture of the .circuit-protective-device . e.g.
4). Type - where relevant for . circuit-breakers enter the sensitivity type .e.g. - C . ( B . C. D . time-characteristics )
5). Rating - enter the .protective-device-current-rating .
6). Breaking-capacity - enter the . protective-device-breaking-capacity . often “printed on the circuit-breakers “ e.g. 6.

GN-3- p.56 . [ Icn ] & [ Ics ] Two-rated-short-circuit-ratings. table - 2.8. [ Icn - 6 ] & [ Ics -6.0 ]
BS-EN-60898 & BS-EN-61009-1 .
[ Icn ] - is themaximum-fault-current . the device can interrupt safely . …….. [ Icn ] value is normally marked on the device [ 6000 ]
[ Ics ] - is the maximum-fault-current . the device caninterrupt safely without loss of . performance .

6). Breaking-capacity - enter the . protective-device-breaking-capacity . often “printed on the circuit-breakers “ e.g. 6.
For- domestic-installations . the ( PFC ) is unlikely to exceed 6kA . up to which value . [ Icn] will equal [ Ics ]

411.4.7.: where a circuit-breaker . Table- 41.3. for the types & ratings . ofovercurrent-devices . listed may be used . instead of calculation .
wherea circuit-breaker - BS-EN-60898 & BS-EN-61009-1 .
2394: our circuits . are . 411.3.2.2. Maximum-disconnection-times . Final-circuits . Notexceeding 32A . [ 0.4s ]

 

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2394: Am making a Point to Note . can’tstress the importance of GN-3 . with Testing& Inspection . “ simplicity at isbest “

GN-3: Ambient-temperature 10°C . 20°C . ( 2394: regulations - 30°C . 70°C )

GN-3: Table - A4 .
Circuit-breakers. Maximum-measured-earth-fault-loop-impedance ( in Ohms ) at ambient-temperature 10°C . where the overcurrent-device is a circuit-breaker .BS-EN-60898 or RCBO to BE-EN-61009-1 .

Ambient-temperature 10°C
GN-3: in comparison .( C ) 6A - 3.09 . 10A - 1.85 .

(B ) 32A - 1.16 ←
Table- A6 : ambient-temperature - correction-factors . 25°C - 1.06 . Cf .
Note. from - 10°C . 0°C . 5°C . 10°C . 20°C . 25°C . 30°C .
Theambient-correction-factor . of Table - A6 is applied to the .earth-fault-loop-impedances . of tables . A1 / A4 if the ambient-temperature is other than . 10°C

GN-3tells us how to do the Calculations .
Ambient-temperature is 25°C . themeasured-earth-fault-loop-impedance . of a circuit-protected by a . 32A type B- circuit-breaker to BS-EN-60898 . should not exceed . 1.16 x 1.06 = 1.23Ω.

GN-3. Do Not Mix up the .ambient-temperature Table . B.2 - 10°C p.121 . Table . B1 - 20°C . p.120
Regulations- 41.3. : ( C ) 6A - 3.83Ω . 10A- 2.30Ω . as you can see . there’s a difference . Yeah

 

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TT-Installations . “ Protective-devices “

Disconnection-timeof ( 0.2s ) for TT- installation hasbeen introduced in the . 17[SUP]th[/SUP] Edition . This makes the use of an . RCD orCircuit-breaker with a . residual-element . virtually-essential .

 

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UsefulJunk . 2394 :

2008:2011:

Asbefore all Appendices are “ Informative “ other than Appendix 1 . which is “ Normative “ .
Appendix1 is requirement & all others are provided for guidance .

 

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2394: Reminder .

By Definition . p.31 . “ Minor-works “
Additions & Alterations to an . installation that do not extendto the . provision of a new-circuit .

 

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2394: Reminder . “ Minor-works “
p.31: - Examples . include the . Addition of socket-outlet : or Lighting-pointsto an ( Existing-circuit ) therelocation of a . light-switch . etc .

 

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2394: - 559.6.1.9.

Part- 5 : p.178 . A Lighting-installation . shall be appropriate-controlled .
Note : See table - 53.4. p.149 .
Forguidance on the selection of (Suitable-protective . Isolation & Switching-devices)

2394: Can we use . Circuit-breaker - BS-EN-60898 .for Isolation . Functional-switching . Emergency--switching .
BS-EN-60898- Yes . (3) Device is suitable for .on-load-isolation . i.e. disconnectionwhilst carrying . Load-current .