Re-take - Useful Information for 2394 :

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O.S.G.p96 .

Re-cap,

For an installation-operating at 400/ 230V , although an insulation-résistance-value of only 1MΩ complies with BS-7671 :

Where.

The insulation-résistance-measured is less than 2MΩ the possibility of a latent-defect-exists .

In these circumstances , each-circuit should then be tested separately .

2394 : Keep in mind written-exams . :gettree: :17:

 

[amberleaf]

O.S.G.p87 . 2392-10 , just starting out on Inspection & Testing . Inspection meaning - Visual is our first line of defence .

One of the most important Regulations in exams , 612.1.
If any test indicates a failure to comply , that test and any preceding-test , theresults of which may have been influenced by the fault-indicated , shall berepeated after the fault has been rectified .

O.S.G. 9.3. Testing .
Testing must include relevant-tests from the following-checklist

O.S.G. 9.3.1. Testing checklist . ◄

Insulation-reading:
Test-instrument , Readings with leads . Open-circuit - > 999MΩ .

Q) if there is no British-Standard then the insulation-résistance should not be less than 1MΩ .

 

[amberleaf]

Leaning - Curve . Only. Old-Notes 2008 . :icon_bs:

From the information given determine ,

The value of the insulation-résistance-measured taken and the requirements of BS-7671: are satisfied . Your-Call . Yeah

1/Rt = 1/R1 + 1/R2 + 1/R3 + 1/R4 + 1/R5

1/Rt = 1/6 + 1/3 + 1/4 + 1/12 + 1/6

Find the lowest-common-denominator i.e. - 12

= 2 + 4 + 3 + 1 + 2 - 12 .

1/Rt = 12 / 12

Therefore : Rt/1 = 12 / 12 = 1MΩ .

Re-cap . Reminder - Guidance-Note - 3 .

Although the requirements of BS-7671: appear to have been satisfied , GN-3 refers to the possibility of a [ Latent-Defect ] existing within the installation . the circuits’ should be tested individually and a minimum-insulation-résistance of 2M is recommended .

As the measurement taken for all of the circuits are above 2MΩ then no investigation would be required .

 

[amberleaf]

Leaning - Curve . Only. Old-Notes 2008 . :icon_bs:

From the information given determine ,

The value of the insulation-résistance-measured taken and the requirements of BS-7671: are satisfied .

1/Rt = 1/R1 + 1/R2 + 1/R3 + 1/R4 + 1/R5 + 1/R6

1/Rt = 1/120 + 1/30 + 1/40 + 1/12 + 1/60 + 1/10

Find the lowest-common-denominator i.e. - 120

= 1 + 4 + 3 + 10 + 2 - 12 - + 12 - 120

1/Rt = 32 / 120

Therefore : Rt/1 = 120 / 32 = 3.75MΩ .

 

[amberleaf]

Electricians , Do I Mixor Match ??

SafeSection of Devices for Installation in Assemblies . August - 2011:

Awarning against the practice of installing devices ( E.g. RCBOs , Circuit-breakers ) of one-manufacturer into assemblies ( E.g. consumer-units . Distribution-boards ) of another-manufacturer . there is evidence that some installers aremixing-products , oftenwithout fully understanding the potential-safety-implications .

Assembliessuch as consumer-units , Distribution-boards and panelboards are tested with specific-devices installed , these devicesare more often than not from the same- manufacturer as the enclosure , testingand certification is undertaken to BS-EN-60439 . formerlyBS-5486 Although BS-5486 is now obsolete there are manyexisting-installations with assemblies complying with this standard and the issues of mixing-different-manufacturer’s devices equally apply , particularly where older-devices maybe difficult to source .

Inall cases , installing-devices other than those declared by the assembly-manufacturer invalidates any testing / certification andwarranty .

BS-7671uts specific-responsibility on the installer . Regulation - 510.3 . requires that the installer takes into account the manufacturer’s-instructions . it is therefore theresponsibility of the installer who intends to , mix-different- manufacturer’s-devices/ components . in an assembly , to undertake appropriate-testingand ensure-conformity with BS-EN-60439 . if this is not done then there is aprobability that , in the event of death . injury . fire or other-damage , the installer would be accountable under , Health & Safety - legislation .

Althoughdevices may appear similar , the dimensions . technical-performance andterminations are not necessarily-compatible .

Distributor and Wholesalerresponsibilities :

A distributor and wholesaler also has aresponsibility under the , general-product-safety-regulations to act “ withdue care “
Distributorand wholesaler should be able to substantiate any advice related to ,interchangeably of devices in assemblies , if the installer acts on a distributor’s - advice and information , andin doing so produces anon-compliant-assembly , then both the distributor and installer may be liable forany-consequences .

 

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Circuit-breakers to BS-EN-60898 &RCBOs to BS-EN-61009-1 in non-preferred-current-ratings

Circuit-breakersto BS-EN-60898
RCBOsto BS-EN-61009-1 are sometimes encountered that have a rated-current other than thepreferred-values [ 3A , 6A , 10A ] listed in Table - 41.3. of BS-7671:2008:2011:

Themaximum-value of ( Zs ) for such a device , at a nominal-voltageof [ Uo - 230V ] can be found from the right-hand-columnof Table - 41.3. of BS-7671:2011:
Table- 41.3 , right gives therelevant-information .

Type - B circuit-breaker . having arated-current ( In ) of 8A ( or the overcurrent-characteristic of an8A Type - B RCBO ) the maximum-value of ( Zs )
at 230Vis 46 / In , = 46 / 8 = 5.75Ω .

Maximum( Zs ) for circuit-breakers to BS-EN-60898 and the overcurrent-characteristic of RCBOs to BS-EN-61009-1for instantaneous-operation giving compliance with the , 0.4 & 5 seconds ,disconnection-times at nominal-voltage [Uo - 230V ]

Table- 41.3.

Type- B - ( Zs ) Ohms for devices ofrated-current ( In ) 46/In .
Type- C - ( Zs ) Ohms for devices ofrated-current ( In ) 23/In.
Type- D - ( Zs ) Ohms for devices ofrated-current ( In ) 11.5/In.

Obsolete-Circuit-Breakers :
Maximum-valuesof ( Zs ) for circuit-breakers for which thisinformation is no longer given in BS-7671: can be obtained either from the edition of BS-7671: that was current when the deviceswere readily-available , or by reference to the manufacture’s - data .

Alternatively, for MCBs to BS-3871: Table - 2 , can be used to find the maximum-value of ( Zs ) at a nominal-voltage of [ Uo - 230V ]

For a Type- 2 circuit-breaker to BS-3871: having a rated-current ( In ) of 30A , the maximum-value of (Zs ) at 230V is [ 32.8 / In = 32.86/ 30 = 1.1Ω ]

Maximum( Zs ) for circuit-breakers toBS-3871: for instantaneous-operationgiving compliance with the , 0.4 & 5 seconds , disconnection-times at anominal-voltage of [ Uo - 230V ]

Type( Zs )
Type- 1 . Ohms - for device of rated-current- ( In ) 57.5/In
Type- 2 . Ohms - for device of rated-current- ( In ) 32.86/In
Type- 3 . Ohms - for device of rated-current- ( In ) 23/In
Type- 4 . Ohms - for device of rated-current- ( In ) 4.6/In

Type- B - ( Zs ) Ohms for devices of rated-current ( In ) 46/In .
Type- C - ( Zs ) Ohms for devices of rated-current ( In ) 23/In .
Type- D - ( Zs ) Ohms for devices of rated-current ( In ) 11.5/In .

Obsolete-fuses :
Maximum-valuesof ( Zs ) for fuses for which this information is no longer given in BS-7671: can be obtained either from the editionof BS-7671: that was current when the deviceswere readily-available , or by reference to the manufacture’s - data .

After 31 - December 2011 : one of these approaches is necessary forfuses to BS-88-2.2. : BS-88-6 : and BS-3871 : as data for them is notincluded in , BS-7671:2008:incorporating Amendment - 1 . 2011:

Overcurrent-protective-devices generally :
Forany type and rated-current of a fuse or overcurrent-circuit-breaker , includingall those mentioned above , the maximum-value of ( Zs ) can be found using the , formula given in Appendix - 3 of BS-7671: Where :- Zs = Uo /Ia .

Uo- is the nominal A.C. r/ms line-voltage to Earth - 230V.
Ia - is the current causing-operation of the protective-devicewithin the specified-time . such as 0.4 or 5 seconds . obtained fromthe manufactures - time / current-characteristics for the particular device-type and rating .

Supposed the manufactures - time / current-characteristic for a 400A - fuse , to BS-88-2.1. gives a value of ( Ia of 2840A ) for a disconnection-time of 5 - seconds . Using the above - formula , the maximum-value of ( Zs ) for the fuse , fordisconnection-time of 5 - seconds and anominal-voltage
( Uo ) of 230V , 230V ÷ 2840A = 0.08Ω

Measured- values of ( Zs ) taking account of conductor -temperature

It should not be forgotten that when comparing ameasured-valued of ( Zs ) with the maximum-value of ( Zs ) allowable for the device used for , fault-protection , account must betaken of the temperature and résistanceof the circuit-conductors . Appendix - 14 of BS-7671: refer .

Provethat the following table-provides instantaneous-disconnection for a BS-EN-60898 & BS-EN-61009-1 - Type B .32A Circuit--breaker using table 41.3. App - 3 .

Zs ≤ Uo /Ia . Table- 41B2

16[SUP]th[/SUP] Edition :
Type- B . 48/In
Type- C . 24/In
Type- D . 12/In

Zs ≤ 240/ 160 = 1.5

48/ 32 = 1.5Ω
240/ 48 = 5. In
32A x 5 = 160A

Mostmanufactures data-shows 3 - 5 x . In for instantaneous-disconnection .

Zs ≤ Uo /Ia .

17[SUP]th[/SUP]Edition : 2008: 2011 :
Type- B . 46/In
Type- C . 23/In
Type- D . 11.5/In

Zs ≤ Uo /Ia . Table - 41.3.

Zs ≤ 230/ 160 = 1.4375 . Round-up to 1.44Ω
46 / 32 = 1.44Ω
230 / 46 = 5. In

Type- B : > 3/In . ≤ 5.0 / In
Type- C : > 5/In . ≤ 10.0 / In
Type- D : > 10/In . ≤ 20.0 / In


If Armoured-Cable is harshly-treated the Amour-wires canbecome-displaced , twisted or stretched , leading to bulges in the sheath-material
Cablesare uniform and circular in cross-section when manufactured , but mishandlingcan result in bulges an kinks which cancause difficulties in pulling into ducts, termination at glands , as well as being unsightly , such problems can be causedby incorrect-pulling from the drum . the introduction of loop and kinks ,pulling round too tight a bend .

 

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Q) a 6A BS-EN-60898 circuit-breaker is used to protect a circuitwith a , maximum-earth-fault-loop-impedance ( Zs ) of 3.83Ω would be type ? Table - 41.3 . p56
B. ……… above 3/In up to including 5/In
C . ……… above 5/In up toincluding 10/In
D. ……… above 10/In up to including 20/In

Youcan’t predicted what level yourcircuit-breaker will trip on , will trip instantly between three and five timesits rated-current [ 3In x 6A = 18A : 5In x 6 = 30A ]
Type- B current for time , 0.1sec to 5 seconds . Fig - 3A4 , p.301 . BS-EN-60898 & BS-EN-61009-1

Calculating- Earth-fault-loop-impedance . Zs = Uo /Ia .
5 times magnetic-settings - 5 x 6A = 30A : Zs ≤ 230V ÷ 30A = 7.67Ω . re-cap Table 41.3 6A = 7.67Ω .

 

[amberleaf]

Thisone always trips up . Q/As -&-s . 2392 . 2394

Q). When testing a 100mA RCD themaximum-test-current applied via the test-instrument will be ? ( G )
3 x In
5 x In
I x In

 

[amberleaf]

RCDscannot detect . Short-circuits or Overloads . due to their design .

Tosummarise the RCD tests . 30mA -Testing .

IΔn / 2. No-tripin 2 seconds . 30mA ÷ 2 = 15.

 

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Because it’s Not in the 17[SUP]th[/SUP]- Edition : 2008: or 2011: Doesn’t not mean it did not Exist . “ Pastto Present “ :icon_bs:

Earthing& Bonding - 2[SUP]nd[/SUP] Edition
Incorporatingthe requirements of BS-7671:2001:
IncludingAmendment , No - 2 .

Looped-main-equipotential-bonding . 2006.

Main-equipotential-bonding-conductor(s) should , ideally, Not be looped from service to service . ( METto Water - Gas )

Solution:
Wherea common-bonding-conductor-loops In and Out,to connect to an ,extraneous-conductive-part . The protective-conductor should beleft-unbroken at the connection .

Thisis so that the ( Continuity ) to other-items connected to thebonding-conductor will not be detached , for example . as a result of work beingcarried out to pipework , refer , Regulation - 528-02-04.

Wherea wiring-system is to be installed in proximity to a non-electrical-service, it shall be so arranged that anyforeseeable-operation carried out on either-service will not cause-damage tothe other .

528.3.3. : 17[SUP]th[/SUP] - Edition .
Wherean electrical-service is to be installed in proximity to a non-electrical-services , it shall be so arranged that anyforeseeable-operation carried out on either-service will not cause-damage tothe electrical-service or the converse . Etc .

Apermanent-label bearing the Words “ Safety Electrical Connection - Do Not Remove “ isrequired in a visible-position at or near the point of connection ofevery-main-bonding-conductor to an , Extraneous-conductive-part , and at themain-earthing-terminal where this isseparate from the main-switchgear - Regulation - 514-13-01.

514-13: 2002 / 2004 : Warning-notices: earthing and bonding-connections .
514-13-01 . A permanent-label to BS-951 , with the words “ SafetyElectrical Connection - Do Not Remove “ shall be permanently-fixed in avisible-position at or near : Etc .

514-13: Warning-notices :earthing and bonding-connections .
514-13.1: A durable-label to BS-951 , with the words “ SafetyElectrical Connection - Do Not Remove “ shallbe permanently-fixed in a visible-position at or near : Etc .

Regulation- 528-02-04 :
Wherea wiring-system is to be installed in proximity to a , non-electrical-serviceit shall be so arranged that any , foreseeable-operation carried out on eitherservice will not cause-damage to the other.

 

[amberleaf]

Useful-Junk: 2001 / 2004 .

Means of earthing in Older-Installation(s)

Older-Installation(s)are sometimes found to employ the water-service-pipe as the sole means ofearthing .
Older-Installation(s)may use a Gas , Water orother-metal-service-pipe as a means of earthing . This is Not-permitted .

Ithas never been permitted to use a , Gas-pipe as a means of earthing and , since 1966 , it has not beenpermitted to use any other-service-pipe either .

Necessary-equipotential-bonding-connections, MUST , be made to the Gas-installation-pipe , Water and other metal-service-pipe(s)

542-02-04 : p113
The metalwork of a Gas , Water or other-serviceshall , NOT be used as aprotective-earth-electrode , this requirement does not preclude the bondingof such metalwork as required byRegulation - 413-02 .

 

[amberleaf]

Labelling of the Earthing-Conductor :

it make life easer for any Inspectors inthe near-future .

the earthing-conductor , the conductor connectingthe installation to the ( Means ) of earthing , Mustbe easily-identifiable .
earthing-conductor(s) are not always labelled where requiredmaking it easily possible to mistakenly-disconnect the wrong-conductor.

a Equipotential-bonding-conductor , mayunintentionally be disconnected when intending to disconnect theearthing-conductor .

Earthing-conductor: [ Protective-conductor ]
Water-service-pipe: [ Main-protective-bonding-conductor ]
Gas-installation-pipe: [ Main-protective-bonding-conductor ]
Distribution-board 1 :
Distribution-board 2 :

MET- Safety-electrical-connection Do NotRemove .

 

[amberleaf]

Blast from the Past :

Earthing-Clamps , Not to be used on Cables , Where did it come from . What Edition ??

BS-7671:2001 .

Earthing-Clamps , Not to be used on Cables .
Earthing-Clamps, must not to be used on Paper-insulated / Lead-sheathed orSteel-wire-armoured ( SWA ) cables .

Under, No-circumstance should an earthing-clamp ( Complying with BS-951 or any other type ) be attached to the , Lead-sheath of any cable.
Inthe case of a supply-cable this practice is wrong for , Two-reasons

Thesupply-cable is the property of the , DNO .
Thesecuring of the clamp to the Lead-sheath is likely to damage theconductor-insulation of the supply-cable . and with the cold-flow of the lead ,the connection is liable to loosen over-time . BS-951 :

1999 States in Note-3 . ( second-sentence) to it’sscope that “ such-clamps are not intended for connection to the armour or sheath of a cable “ :icon_bs:

Inthe worst-cases , this practice may lead to increased-risk from the hazards of fire or electrical-shock .

 

[amberleaf]

2001 / 2011:

Blast from the Past : :icon_bs:

Earthing-Clamps , Not to be used on Cables :

Many installations are supplied by , Lead-sheathed-incoming-service-cables, and earthing-facilities are often provided , by DNO by means of a ( Wiped-soldered-joint on to the Lead-sheath ) with an attached-earth-tail to an earthing-block .

Wherean adequate earthing-facility has not been provided , electrical-contractorsare advised always to enquire of the cable-owner ( such as the DNO whether or not such a facility can be made available, it must never be assumed that , because a supply-cable has a , Lead or other metallic-sheathor armour , it is capable of providing an effective-connection to Earth . orthat it is adequate for carrying the ( PFC)

The compressive-forces-exerted by tighteninga clamp , onto most types of armoured ormetal-sheathed-cables ( sufficient toprovide a Low-résistance joint for fault or other-currents to flow ) are liable to cause damage to theconductor-insulation and bedding . such misuse of a clamp is a departure fromthe Regulation - 512-05-01 .

One solution open to the . installation-designer is to make the ,installation part of a , TT - system .

Regulation- 512-05-01
Every item of equipment shall be selected anderected so that it will neither cause harmful-effects to other equipment nor-impair the supply during-normal-service including-switching-operations .

Regulation- 512.1.5. p/114
Every item of equipment shall be selected anderected so that it will neither cause harmful-effects to other equipment nor-impair the supply during-normal-service including-switching-operations .

 

[amberleaf]

Re-cap .

Exposed-conductive-parts : :icon_bs:
Arenot simply conductive-parts that are ,Exposed or Accessible . such as metal-table . the definition of an Exposed-conductive-part is a conductive-part ofequipment which can betouched

Whichis not live-part but which may become live under fault-conditions .

Bydefinition : p/27 . will indicate thatequipment - Means
Electrical-equipment, and electrical-equipment is an item which generates , converts , transmits , distributes orutilises electrical-energy . Etc
So what is an , Exposed-conductive-part:

Be part of electrical-equipment .
Be able to be Touched
Whichis Not normally-live
Butwhich can become live underfault-conditions

Extraneous-conductive-parts :
Extraneous-conductive-part for it is simply any piece of Extraneous-conductive-material , an Extraneous-conductive-part is a conductive-part of the electrical-installation .

Theessence of an , Extraneous-conductive-part is that it is likely to ( Introduce ) earth-potential into a Building / Installation .
Extraneous-conductive-parts : be ( Exposed) Conductive and in generalcontact with the mass of Earth .

p/28. Extraneous-conductive-part.
a conductive-part ( Introduce ) a potential generally Earth-potential .
Not forming-part ofthe electrical-installation .

By definition : p/27

Electrical-equipment :
(abbr : Equipment ) Any item for such purposes as

Generation.
Conversion.
Transmission.
Distributionor utilisation of electrical-energy suchas

Machines’
Transformers
Apparatus
Measuring-instruments
Protective-devices
Wiring-systems
Accessories
Appliances and luminaires .

Electrical-installation :
(abbr : Installation ) An assembly of associated-electrical-equipment having co-ordinated characteristics to fulfil specific-purposes .

 

[amberleaf]

Whilstmeasuring the earth electrode resistance , the earth lead of an earth loopimpedance tester should be connected to ?
- The incoming-line .
- The main-earthing-terminal
- the neutral-conductor only
- The disconnected-earthing-conductor .

Wherea 100mA RCD is protecting a TT installation , when tested at ( ½ ) it should
- Operate within 200mS
- Not operate
- Operate within 300mS
- Operate within 40mS

The ( R[SUP]1[/SUP]+ R[SUP]2[/SUP] ) reading taken at sockets during a continuityof ring-final-conductors test should be approximately ?
r[SUP]1[/SUP]+ r/n / 4
r[SUP]1[/SUP] + r[SUP]2[/SUP] / 4
r[SUP]1[/SUP] + r[SUP]2[/SUP] / 2
R[SUP]1[/SUP] + R[SUP]2 [/SUP]/ 4

Whichof the following test instrument would be most likely to give a reading of 2.5kA ?
Low-résistance-ohmmeter
RCD-tester
Insulation-résistance-tester
Prospective-fault-current-tester.

Theaccuracy of digital test instrument as recommended by Guidance-Note 3 is ?
0.04
0.05
0.02
0.1

Ifthe C.S.A. of a protective-conductor increases , thiswill lead to ?
- A decrease in résistance .
- An increase in résistance .
- An increased ( Zs ) reading
- An reduction in operating-current .

Accordingto GS-38 , test-leads should be . ?
Individually-coloured
Colouredbrown and blue .
Non-flexible
Insulatedto 230V

ATT - installation is protected by a 300mA - RCD . the maximum value ofearth-electrode-résistance is given byGN-3 as . ?
500Ω
1660Ω
100Ω
160Ω

Accordingto GN-3 is the correct-sequence of the following-dead-tests . 1 - Continuity ofthe ring-final-conductors . 2 - Polarity . 3 - Insulation-résistance . 4Continuity of CPC .
2. 3 . 4 . 1 .
4. 1 . 2 . 3 .
1. 2 . 3 . 4 .
4 . 1 . 3 . 2.

When testing a ring-final-circuit , the résistancereadings of ( R[SUP]1[/SUP] + R[SUP]2[/SUP]) will be . ?
Approximately 1.87 x R[SUP]1[/SUP]+ Rn
Approximately 2 x R[SUP]1 [/SUP]readings
Approximately 1.67 x R[SUP]1[/SUP] & Rn readings .
Approximately 1.67 x R[SUP]1[/SUP] & R[SUP]2 [/SUP]readings .

Whichof the following should be carried out when conducting aninsulation-résistance-test . on a 2 -way lighting-circuit . ?

Ensurethat Edison-screw light bulbs are connected in the Line-conductor only .
Bridgeout the switches .
Ensurethat both switches are in the on-position .
Operate all switches duringthe test .

It is often necessary to control a lampfrom more than one location , By utilising 2-way switches and strappers ( thecables in between the two operating switches )
Wecan effectively control the lamp from 2-different locations , such asthe top and bottom of stairs , known asthe “ conventionalmethod “

Whichcolumn would you record the results from the long-lead-test-method used todetermine continuity of the protective-conductors . ? Wander-lead-method .
Zs.
PFC.
R[SUP]2[/SUP].
(R[SUP]1[/SUP] + R[SUP]2[/SUP])

Which of the following tests would be carried out first ?
Earth-fault-loop-impedance
Insulation-résistance
Continuity of ring-final-conductors
Prospective-fault-current

 

[amberleaf]

The minimum-test-voltage that should be appliedwhen testing the insulation-résistance of a SELVcircuit is ?
500V d.c.
500V a.c.
250V d.c.
250V a.c.

An RCD when tested at 100% ( x1 times ) of its trip-rating should ?
Not-trip
Trip within 300mS
Trip within 40mS
Trip within 100mS

Some of the essential andoptional-information required on the , Electrical-Installation-certificate and Minor-Electrical-Installation-Work-certificate is ?
Number of rooms , type of lighting ,outdoor-supplies
Floor-area, separate building , number of floors
Means of earthing, main-protective-conductors andsupply-characteristics
Name of sub-contractor , invoice , contact-number

Before carrying out an Insulation-résistance test ?
Carry out verification of voltage-drop. ► ( Regulations - 612.14. p/194 . Note : Verification of voltage-drop is not normallyrequired during initial-verification )
Ensure supply is switched on
Contact local-authority-building-control
Safely-isolate and consider electronic-equipment andvoltage-sensitive-equipment

Prospective-fault-current-measurement ensures that ?
Cables can carry the required-load-current
The consumer-unit-main-switch can be operated during a fault
The overcurrent-protective-devices at that point in the installation can disconnect ( Overload / Overloaded - Overcurrent )
The main-fuse will operate in the event of afault .

Overcurrent-Protective-Devices :
Protection against overload , & short-circuits in electrical-equipment .
O.S.G.- p/23 Note . RCBOs - Overload , Short-circuit , Earth-fault . MCB/ RCBO ( Overload-protection - Fuses ) its inthe Questions

A Minor-electrical-certificate does not require details of ?
System-earthing-arrangements
Departures from BS-7671:
Method of fault-protection
Prospective-fault-current. ( PFC )

Once an Electrical-Installation-certificate has been completed theoriginal should be ?
Sent to the local-building-control
Retained by the electrical-contractor
Given to the person ordering the work
Given to the tenant of the building .

Test-Leads to GS-38 should have ?
1mm exposed-probe , non-fused and finger-barriers
2mm exposed-probe , non-fused-lead or current-limiting and finger-barriers
2mm exposed-probe , fused-lead or current-limiting and finger-barriers
1mm exposed-probe , fused- lead or current-limiting and finger-barriers

► 2mm exposed-probe ( for live-testing ) “ Fingers “ or Hands
► 4mm exposed-probe ( for dead-testing )

During the initial-inspection and testing sight would indicate a fault such as ?
Overheating
Equipment-overheating
Vibration of transformer-cover
Damaged-equipment .

 

[amberleaf]

Metallic supply-pipework can be used for anearth-electrode if ?
It is water-utility-pipework
It is other than water-utility-pipework
It is an unused-gas-pipe that is less than10-years old
It is other than utility-pipework providing-precautions have been taken . BS-7671:2011 . p/159 - 542.2.6.

If running in permitted-zones are used as protection against impact , whatextra-measure would be required if the installation was in a domestic-premises ?
Run cables with capping-fitted
All circuits protected with a30mA RCBO
Cables to have additional-protection by means of 30mA RCD BS-7671:2011/125 . 522.6.102
Cables to have additional-protection by means of 100mA RCD

When assessing-circuits for any need of continuity of service , the following-characteristic that does notneed to be considered is ?
Multiple-power-supplies
Selection of earthing-system
Lighting-protection ( BS-7671:2011. p/ 49 . 361.1
Number of circuits

When automatic-disconnection of supply is used as a measure of protection , additional-protectionby RCD shall be provided for ?
Mobile-equipment having a rating of greater than 32A
Socket-outlets in commercial and industrial-locations
Only for sockets-rated at 32A or less where it is reasonable to expect they may be used to supply-equipment for use outdoors
Socket-outlets-rated at 20A or less in a domestic-installation ( BS-7671:2011: p/54. 411.3 )

All circuits in a location containing a bath or shower shall have ?
A disconnection time of 0.4s
Be installed at a depth of at least 50mm
Be installed using earthed-conduit
Additional-protection by a 30mA RCD . ( BS-7671:2011: p/199 . 701.411.3.3.

The installation reference for multicore-cables clipped-direct is ?
30
C ( BS-7671:2011. p/318 . number - 20
A
13

Automatic-disconnection of supply is used as a method of protectionfor ?
Indirect-contact
Basic-protection
Fault-protection ( BS-7671:2011: definitions )
Direct-contact

 

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How things change - 1991 / 2011 : 15[SUP]th[/SUP]/ 16[SUP]th[/SUP] - 17[SUP]th[/SUP] edition 2011:

Sixteen Edition 1991:

ThisEdition was issued on 10 may 1991 . it isintended to supersede the fifteen-edition , fifteen-edition will bechanged to the sixteen-edition to take effect from 31-december 1992.

130-09: Additions and Alterationsto an Installation : 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
130-09-01. No addition or alteration , temporaryor permanent , shall be made to an existing-installation , unless it has been ascertainedthat the rating and the condition of any existing-equipment , including that ofthe supplier , which will have to carry any additional-load is adequate for the altered-circumstances andthe earthing-arrangement is also adequate .

132.16 : Additions and Alterationsto an Installation : 17[SUP]th[/SUP] - edition
Noaddition or alteration , temporary or permanent , shall be made to anexisting-installation , unless it has been ascertained that the rating and thecondition of any existing-equipment , including that of the distributor , will be adequate for thealtered-circumstances , furthermore , the earthing and bonding-arrangements ,if necessary for the protective-measure applied for the safety of the additions and alteration , shall be adequate .

Comparing things form the past - Editions “ What’s in a Wording “

 

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Comparing things from the past - Editions

15[SUP]th[/SUP]/ 16[SUP]th[/SUP] . 1991 / 1992 .
Earthed-equipotential-zone:
A zone within which , exposed-conductive-partsand , extraneous-conductive-parts are maintained at substantially the sane-potential by-bonding , such that , underfault-conditions , the differences in potential between-simultaneously-accessible , exposed and extraneous-conductive-parts will not cause electric-shock .

Earthing: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
The act of connecting the , exposed-conductive-partsof an installation to themain-earthing-terminal of an installation .

Earthing: 2011 :
Connection of the exposed-conductive-parts of an installation to the main-earthing-terminalof that installation .

Equipotential-bonding: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
Electrical-connection-maintaining various , exposed-conductive-parts and extraneous-conductive-parts atsubstantially the same-potential .

Equipotential-bonding: 2011:
Electrical-connection-maintaining various , exposed-conductive-parts and extraneous-conductive-parts atsubstantially the same-potential . ( see also Protective-equipotential-bonding )

Exposed-conductive-part: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
A conductive-part of equipment which can be touched and whichis not a live-part but which may become live under fault-conditions .

Exposed-conductive-part: 2011:
Conductive-part of equipment which can be touched and whichis not a normally live , but which can become live under fault-conditions .

Extraneous-conductive-part: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
A conductive-part liable to introduce a potential , generallyearth-potential , and not forming-part of the electrical-installation .

Extraneous-conductive-part: 2011:
A conductive-part liable to introduce a potential , generally Earth-potential, and not forming-part of the electrical-installation .

Prospective-fault-current: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
The value of overcurrent at a given-point ina circuit resulting from a fault of negligible-impedance betweenlive-conductors having a difference ofpotential undernormal-operating-conditions , or between a live-conductor and an , exposed-conductive-part.

Prospective-fault-current: 2011: ( Ipf )
The valueof overcurrent at a given-point in a circuit resulting from a fault ofnegligible-impedance between live-conductors having a difference of potential under normal-operating-conditions , or between a live-conductor and an ,exposed-conductive-part .

Earth-fault-current: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
A fault-currentwhich flows to Earth .

Earth-fault-current: 2011:
A current resulting from a fault of negligible-impedancebetween a line-conductor and an , exposed-conductive-part or a protective-conductor .

Earth-fault-loop-impedance: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
The impedance of theearth-fault-current-loop starting andending at the point of earth-fault , this impedance is denoted by the symbol; ( Zs )

Earth-fault-loop-impedance: 2011:
The impedance of theearth-fault-current-loop starting andending at the point of earth-fault , this impedance is denoted by the symbol; ( Zs )

Gas-installation-pipe: 15[SUP]th[/SUP] / 16[SUP]th[/SUP]
Any-pipe, not being a service-pipe ( other thanany-part of a service-pipe comprised in a primary-meter-installation ) or apipe comprised in a gas-appliance , for conveying gas for a particularconsumer and including any associated-valve or other-gas-fitting.

Gas-installation-pipe: 2011:
Any-pipe, not being a service-pipe ( other thanany-part of a service-pipe comprised in a primary-meter-installation ) or apipe comprised in a gas-appliance , for conveying gas for a particularconsumer and including any associated-valve or other-gas-fitting.

Has thing changed much .