Re-take - Useful Information for 2394 :

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Extract's from 2009 / 2391 .
Working my way around the Guidance Note 3 . learning curve

Q) Three items to be checked , as identified on the Schedule of Inspections , where fault-protection is provided by automatic disconnection of supply ( ADS )

GN-3 P/20 . Method 1 : automatic disconnection of the supply ( ADS )

You're Q , Presence of appropriate protective-conductor(s)

542.3. Earthing conductor .
Sect 543. Circuit-protective-conductor(s)
Sect 544. Protective bonding conductors
- main bonding conductors
- supplementary bonding conductors .. ( where required )

312.2. The earthing system must be determined e.g.
► TN-C-S system ( protective multiple earthing ( PME))
► TN-S system
► TT system ( earth electrode(s)

411.4.5. The earth fault loop impedance must be appropriate for the protective device i.e. RCD or overcurrent device .

GN-3 P/97 . Schedule of Inspection ( for new installation work only )
Fault protection
i) Automatic disconnection of supply

You're Q . Check for Presence of :
(✓) Presence of earthing conductor
(✓) Presence of circuit-protective-conductors
(✓) Presence of protective-bonding-conductors

Choice of protective devices . ? Circuit-breaker , RCD / RCBO .

Additional protection:
(✓) Presence of resi/dual current devices(s)

O.S.G. P/85/86 Inspection :
9.2.2. Inspection checklist , viii ( d 415.1. additional protection by RCDs )

 

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BS-7671:2011: Learning curve .

[h=4]• On the new Electrical Installation Condition Report, the first few lines of the inspection schedule (1.1 – 1.6 & 3.1) relate to the verification of the distributor’s/supply intake equipment. What should I recommend if that equipment is in a dangerous or potentially dangerous condition[/h]
Where inadequacies in distributor's equipment are observed , the contractor should recommend that the person ordering the report requests the distributor or meter operator , as appropriate , to carry out remedial work as necessary to remove the danger or potential danger .

Distributors and meter operators have an obligation under the Electrical Safety , Quality and Continuity Regulations 2002 ( ESQCR ) to maintain their equipment , so far as is reasonably practicable , to prevent danger .

Condition Report - Inspection schedule P/400
1.1. ) Service cable condition
1.6. ) Condition of isolator ( where present )
3.1. ) Presence and condition of distributor's earthing arrangement ( 542.1.2.1. : 542.1.2.2. )

R/P 403 . Examples of Items requiring Inspection for an Electrical Installation Condition Report
Electrical Intake Equipment
• Service cable
• Service cut-out / fuse
• Meter tails - Distributor
• Meter tails - Consumer
• Meter equipment
• Isolator
Where inadequacies in distributor's equipment are encountered , it is recommended that the person ordering the report informs the appropriate authority

 

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2394 : Calculations

Determine, showing all calculations, whether a test result of 0.06Ω is acceptable if the ► main protective bonding conductor is ( 33m long )
Length of conductor ( 33m )
O.S.G. p182 : Resistance of cable 1.83mΩ/m .. ( Protective-conductor 10mm[SUP]2[/SUP] )
D.C. résistance = ( 33m x 1.83mΩ/m ) /1000

33 x 1.83 = 60.39 ÷ 1000 = 0.06039 .. Q) is this acceptable -&-s

 

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Determine, showing all calculations, whether a test result of 0.06Ω is acceptable if the ► main protective bonding conductor is ( 33m long )
length * milliohms' per metre / 1000

Length of conductor ( 33m )
O.S.G. p182 : Resistance of cable 1.83mΩ/m .. ( Protective-conductor 10mm[SUP]2[/SUP] )
résistance = ( 33m x 1.83mΩ/m ) /1000

33 x 1.83 = 60.39 ÷ 1000 = 0.06039 .. Q) is this acceptable -&-s

Typo error ( D.C. )

 

[amberleaf]

From my old notes 16th Edition , Sound advice , My old tutor

Requirement of BS-7671: & the Electrically at Work Act Regulation 1989 That any electrical installation shall be ( Verified ) as safe to operate before being Energised .

The term " Safe to operate " means the user of the electrical installation will be free from the risk of , fire , shock , burns & injury . Etc
" Safe to operate " also means that the user of the installation should not require technical knowledge in order to stay clear of the casualty department of the nearest hospital

 

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Sometimes the term IP is used as an abbreviation for " Ingress Protection "

IP ratings are defined as IPXX. The initial " X " is a number from 0 to 6 indicating the degree of protection against ingress by solid objects, and the second " X " is a number from 0 to 8 indicating the degree of protection against ingress by water.

Degrees of protection against solid objects :

IP0X Non-protected
IP1X 50mm diameter and greater
IP2X 12.5mm diameter and greater
IP3X 2.5mm diameter and greater
IP4X 1.0mm diameter and greater
IP5X dust-protected
IP6X dust-tight

Degrees of protection against water : ( Liquid protection )
X Indicates no specified protection

IPX0 Non-protected
IPX1 Vertically falling water drops ( such as from condensation from surfaces )
IPX2 Vertically falling water drops with enclosure tilted up to 15 degrees ( vertical )
IPX3 Spraying water ( at any angle up to 60° on either side of the vertical )
IPX4 Splashing water ( against the enclose from any direction )
IPX5 Water jets ( projected against the enclosure from any direction , such as from hosepipes )
IPX6 Powerful water jets ( projected against the enclosure from any direction , such as from power jets sprays , or sea waves )
IPX7 Temporary immersion ( of enclosure in water under specified conditions )
IPX8 Continuous immersion ( of enclosure under specified conditions )

Equipment enclosures of an installation need to be correctly selected, installed and maintained to meet the requirements of BS-7671, and the manufacturer. For example, an enclosure needs to have an appropriate IP code, and impact résistance against any likely mechanical damage. Cable glands fitted to an enclosure also need to have an IP code at least equal to that of the enclosure.

Covers of an enclosure need to be securely fixed, and access doors left tightly shut.


The most commonly quoted IP codes in the 17th edition are IPXXB or IP2X, and IPXXD or IP4X. The X denotes that protection is not specified, not that there is no protection. For example,

IPXXB denotes protection against finger contact only
IPXXD denotes protection against penetration by 1mm diameter wires only

 

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IP Codes
This guide gives basic information about the IP (International Protection)1 code, based on information given in ‘BS EN 60529: 1992 – Specification for degrees of protection provided by enclosures (IP code)’, where you can find further details if necessary.

BS-EN-60529 describes a system for classifying the degree of protection given by enclosures of electrical equipment. This is to protect:

a) persons against ‘access to hazardous parts inside an enclosure’, and
b) equipment inside an enclosure against the ‘ingress of solid foreign objects or dust’ and ‘the harmful effects from ingress of water or moisture’.

Electrical equipment enclosures are specified in the form IPXX. As appropriate, the ‘first’ and/or ‘second’ X is replaced by a number as shown in Tables 1 and 2, respectively, of this guide.

As an example, for IP2X, the 2 (from Table 1) defines an enclosure giving protection against ingress of solid foreign objects with a diameter of 12.5 mm, and from a finger being inserted and accessing hazardous parts; the X means there is no protection against ingress of water specified.


A letter A, B, C or D, as shown in Table 3, is sometimes added after XX. As an example, IPXXB, the XX means that the first and second numbers are not specified, and the B means finger protection is provided against any hazard in the enclosure.
Table 1
Protection of equipment inside the enclosure against ingress of solid objects or dust
1st number :
0 . No protection
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure . No protection
1 . 50mm diameter object 50
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure . Back of hand
2 . 12.5mm diameter solid foreign object 12.5
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure . Finger standard jointed test ( 12mm diameter , 80mm length )
3 . 2.5mm diameter solid object 2.5mm
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure . Tool
4 . 1.0mm diameter solid foreign object 1mm
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure . Wire
5 . Dust-protected ( Ingress of dust not totally prevented , but must not interfere with satisfactory operation of equipment or reduce safety )
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure . Wire
6 . Dust-tight ( No ingress of dust
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure .

Additional Letter of IP Code table 3
Protection of persons against access to hazardous ( live or moving ) parts inside the enclosure
Letter ( A ) Back of hand ( 50mm diameter )
Letter ( B ) Standard jointed test finger ( 12mm diameter 80mm length )
Letter ( C ) Tool 2.5mm diameter 100mm length
Letter ( D ) Wire 1.0mm diameter 100mm length

 

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IP2X . finger protection , This is barriers and enclosures generally
IPXXB . This means the same as above , Only the ( B ) stands for finger barrier
IP4X . This is a standard for the top of enclosures such as consumer units

 

[Richard Burns]

612.4.5. Basic protection by a barrier or an enclosure provided during erection .
Where basic protection is intended to be afforded by a barrier or an enclosure provided during erection in accordance with Regulation 416.2. it shall be verified by a test that each barrier or enclosure affords a degree of protection not less than IPXXB or IP2X , or IPXXD or IP4X as appropriate , where that regulation so requires .

Basic protection by a barriers or enclosures provided during erection

This is a test to verify that each barrier or enclosure provided during erection gives suitable protection against the risk of electric shock through contact with live parts by fingers , solid objects and the like .

The test also applies to barriers or enclosures which , although provided in factory-built equipment , have been affected by the erection process . for example , if an opening has been formed in an enclosure on site for the entry of cables , but is oversized or unused , the enclosure must be capable of meeting the test criteria in order to comply with the requirements of BS-7671:2008:2011: if the enclosure fails to comply when tested , remedial action should be taken (such as reducing the size of the opening )

The degree of protection provided by each barrier or enclosure must not be less than ( IP2X ) or ( IPXXB )
For readily accessible top surfaces the degree of protection must not be less than ( IP4X).

IP2X means that the barrier or enclosure provides protection against contact with live parts by a standard test finger which is ( 12mm in diameter , 80mm long and is capable of bending through 90° twice in the same plane ) like a normal finger . The test finger is applied with a force , not exceeding a specified maximum value and is used in conjunction with an electric signalling circuit . ( IPXXB ) is equivalent to ( IP2X ) in this context .

IP4X is protection against the entry of a wire , strip or similar object which is more than ( 1mm thick ) or a foreign object which is greater than 1mm diameter )

in practice a ( Visual Inspection ) will usually be sufficient to confirm the compliance or otherwise of the barriers or enclosures with the above requirements . if all unused entries are suitably closed , a test may not be necessary .

BS-7671:2008:2011: P/67 barriers or enclosures .. Top of Consumer unit or DB
416.2.2. A horizontal top surface of a barriers or enclosure which is readily accessible shall provide a degree of protection of at least IPXXD or IP4X

BS-7671:2008:2011: P/67 barriers or enclosure .. Side & Bottom
(iii) where an intermediate barrier providing a degree of protection of at least ( IPXXB or IP2X ) prevents contact with live parts , by the use of a key or tool to remove the intermediate barrier

 

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The Chief Examiners’ Report has been reintroduced as a result of feedback from centres, to give them guidance in preparing candidates for the written examination.

2394 : Please read GN-3 that's why it's called Guidance Notes

There appears to be a lot of misunderstanding regarding the testing of an earth-electrode for a generator. In this particular case the generator was the standby supply for a rural ambulance station.

Common errors included:
Seeking permission to isolate the supply to the installation to carry out the test: result in the generator starting up. The supply did not require isolation but the generator did. Stating the test is carried out with an earth-fault-loop-impedance-tester or a low-résistance-ohmmeter when the test is performed using an earth electrode résistance tester.

Incorrect location of the test electrodes: these were often placed either side of the electrode under test. When correctly located the distance between the electrode under test and the current electrode dictates the positioning of the potential electrode being centred and at + 10% and - 10% of the stated overall distance.

Many candidates used varying overall distances (acceptable) but then stated a potential electrode moved 3 m, some at 6 m etc, which was not 10% of their given overall distance.

Electrodes correctly located and then tests carried out between each electrode in turn.

 

[amberleaf]

Ring final circuit is protected by a ( BS-3036 ) semi-enclosed-rewirable-fuse . Table 41.2.
& the measured ( Zs ) is 0.97Ω

This is a ring final circuit the disconnection time has to be 0.4s . from Table 41.2 - BS-7671: the maximum ( Zs ) for a 30A rewirable-fuse ( 1.09Ω )

The rule of thumb can now be applied which means that 80% of the value must be calculated.
This can be achieved by multiplying it be 0.80 ... 1.09 x 0.80 = 0.87Ω

The measured value for the circuit must now be lower than the corrected value if it is to comply with BS-7671:

Measured value - 0.97Ω
Corrected value - 0.87Ω

The measured value of ( Zs ) is higher
When recording ( Zs ) for a circuit , measuring ( Ze ) and then adding ( R1 + R2 ) is the preferred method because it will give an accurate value

Whereas direct measurement will include parallel paths and because of this will often give lower readings
Ze + ( R1 + R2 ) should always be used for an initial verification as the ( first recorded value ) will be used as a benchmark to be compared with results taken in ( future periodic tests )

 

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The résistance of the copper conductors will rise by 2% for each 5°C rise in temperature , with that in mind if the ( R1 + R2 ) values are measured at 20°C , and the temperature of the conductor rises to its maximum temperature of 70°C when carrying a load , you can see that the temperature rise of the conductors is 50°C .

As the résistance rises by 2% for each 5°C rise in temperature then the résistance must rise by 20% , as there is 10 x 5°C in 50°C . if the rise is 2% for each 5°C then the increase in résistance will be 10 x 2% = 20%

To increase any value by 20% you simply multiply it be ( 1.2 ) O.S.G. Table 13 ...... ( 1.2 ) is the multiplier for temperature correction .

Table 12 O.S.G.
Ambient temperature multipliers to Table 11
Expected ambient temperature ( °C )
5°C .. Multiplier values 0.94 ............ The résistance of the copper conductors will rise by 2% for each 5°C rise in temperature .
10°C .. Multiplier values 0.96 ............ etc
15°C .. Multiplier values 0.98 ............ etc
20°C .. Multiplier values 1.00 ............ etc
25°C .. Multiplier values 1.02 ............ etc

Table 13 O.S.G. Multiplier to be applied to Table 11 to calculate conductor résistance at maximum operating temperature ( note 3 ) for standard devices ( note 4 )

different scenarios .

Where the ( R1 + R2 ) values for the circuit length have been calculated using the r1 + r2 values from Table 11 O.S.G.
Q) Circuit is wired in 2.5mm with a 1.5mm CPC and is 21m long .
Value of r1 + r2 for this size copper conductor is 19.51mΩ/m at 20°C
21m of this cable will have a résistance ( R1 + R2 ) of ........ 19.51 x 21 ÷ 1000 = 0.4Ω

This is of course at 20°C . you now have to calculate the résistance at which the conductor will be if it is operating at a temperature of 70°C
To do this you must multiply the R1 + R2 value by a factor of ( 1.2 ) ........... 0.4 x 1.2 = 0.48Ω

This will be the résistance which the conductor will reach at 70°C . To calculate ( Zs ) you must add ( 0.48 ) to the measured ( Ze value ) This value of ( Zs ) can now be directly compared with the maximum values given for ( Zs ) in chapter 41 of BS-7671: Providing your value is equal to or less than the maximum value the circuit will be satisfactory .

Chapter 41 : Protection against electric shock .

Where the length of the circuit is not known and the value of R[SUP]1[/SUP] + R[SUP]2[/SUP] has been measured using the ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) method an accurate calculation can be obtained by using the multiplier values provided in

Table 12 O.S.G.
Ambient temperature multipliers to Table 11
Expected ambient temperature ( °C )
5°C .. Multiplier values 0.94
10°C .. Multiplier values 0.96
15°C .. Multiplier values 0.98
20°C .. Multiplier values 1.00
25°C .. Multiplier values 1.02

This is because the table is intended to be used to calculate the résistance value of a conductor when you known the temperature that is going to operate at . in you case you are going to measure the temperature of the room , & calculate the résistance of the cable back to what it would be at 20°C

Ambient temperature multipliers to be applied to ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) values are shown in Table 12 O.S.G.

Example : that you have measured an ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) value of ( 0.84Ω ) and you have measured the ambient temperature at 25°C
by calculation : R[SUP]1[/SUP] + R[SUP]2 [/SUP]/ temp/factor - the value of résistance at 20°C ..... 0.84 ÷ 1.02 = 0.82Ω value of résistance at 20°C

Having corrected the measured value to what it would be at 20°C ., the next step is to calculate what the résistance of the cable would be at its operating temperature

This is where you use the ( 1.2 multiplier ) .. Table 13 O.S.G.
The résistance of the cable at its maximum operating temperate of 70°C .... 0.82 x 1.2 = 0.98Ω
This value can now be added to the measured ( Ze ) to provide a value of ( Zs ) which can be compared to the maximum ( Zs values ) provided in Chapter 41 of BS-7671:

 

[amberleaf]

The ( Ze ) of an installation is 0.32Ω
A circuit has been installed using T&E 70°C thermoplastic ( pvc ) cable
The room is 25°C and the measured ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) value is 0.52Ω

The circuit is protected by , BS-EN-60898-1 20A type C circuit-breaker
Correct the cables résistance to 20°C by using the factor from O.S.G. Table 12 P/183

By calculations' : 0.52 ÷ 1.02 = 0.51Ω
Adjust this value to the conductor operating temperature by increasing it by 20% .. By calculations' : 0.51 x 1.2 = 0.61Ω
You must add this value to the installation ( Ze ) to find ( Zs ) .. By calculations' : 0.61 + 0.32 = 0.93Ω

This is the calculated value of ( Zs ) when the circuit is operating at its maximum capacity
This value can now be compared directly to the maximum value of ( Zs ) for a 20A BS-EN-60898-1 type C circuit-breaker .
Your value is Table R/P 56 , 41.3 , C circuit-breaker 20A - 1.15Ω
To comply with the regulation , the actual value of 0.93Ω must be equal to / or lower than the maximum value which is 1.15Ω

 

[amberleaf]

This is probably the most used and is certainly the most convenient as it requires one measurement and one minimal calculation , this method is known as the rule of thumb .

R/P 56 Table 41.3.
The circuit is protected by a 32A type B - BS-EN-60898-1 circuit-breaker with a maximum ( Zs ) value of 1.44Ω The ( Zs ) for the circuit has been obtained by ( Direct measurement ) and is 1.18Ω , All that is required for this method is to look up the maximum ( Zs ) permissible for the protective device .

You must multiply the maximum value by ( 0.8 ) 1.44 x 0.8 = 1.15Ω
You must now compare the measured value to the recalculated maximum value ,
The measured value must be EQUAL to or LOWER than the recalculated maximum value

You can see the measured values is 1.18Ω and the recalculated value is 1.15Ω .

2394 , You call < > your measured value is HIGHER of the TWO . is it Acceptable or Not .

 

[amberleaf]

GN-3 This Guidance Note is concerned principally with Part 6 of BS-7671: Inspection & Testing

• Gaining familiarity with IET Guidance Note 3 and its content is also an important aspect .
• The BS-7671: requirements for initial verification , inspection , testing & certification & reporting .
Interpretation of test results is a vital part of the testing process , Why ? The correct selection and use of tables from BS-7671: and from O.S.G. & GN-3

Inspection & Testing of electrical installation(s)
Why inspect & test

The Electricity at Work Regulation 1989 is a ( statutory document ) it is a legal requirement that statutory regulations are complied with .
These regulations are required to ensure that places of work provide a safe , well maintained system .
To provide this is to ensure the newly installed circuit(s) and existing installations are , Tested on a regular basis

By the book GN-3 : 3.3. Electricity at Work Regulations
Regulation 4(2) of the Electricity at Work Regulations 1989 requires that :
As may be necessary to prevent danger , all systems shall be maintained so as to prevent , so far is reasonably practicable , such danger , refer .

The British standard for electrical installations is BS-7671:2008:2011: the requirement for electrical installations , Within this standard , Regulation
Electrical : test certificates are used to record what has been done and confirm that the installation meets the required standard Regulation 610.1. States that " every installation shall , during erection and on completion before being put into service , be inspected and tested to verify , so far as reasonably practicable . that the requirements of the regulations have been met "

Certification & Reporting

Electrical Installation Certificate .. ( EIC )
Minor Electrical Installation Works Certificate .. ( MEIWC )

BS-7671:2011: has stated the facts .
This Report is an important and valuable document ....
Electrical Installation Condition Report .. ( EICR ) - Condition Report - for the person producing the Reporting
This Report should only be used for reporting on the condition of an existing electrical installation
Periodic Inspection & Testing .. The purpose of this Condition Report is to Confirm , so far as reasonably practicable , whether or not the electrical installation is in a satisfactory condition for continued service

GN-3 1.3. The client
1.3.1. Certificates and Reporting .
Following the periodic inspection and testing of an existing installation , an ( EICR ) together with schedule of inspection and schedule of test results , are required to be given to person ordering the inspection

( EICR ) documentation comprises the following .. Purpose of
Schedule of Inspections .. one or more
Condition Report Inspection Schedule for Domestic & Similar with up to 100A supply ..... Note : This form is suitable for many types of smaller installations not exclusively domestic .
( Generic ) Schedule of Test Results .. one or more ... Test results and compared with relevant criteria

GN-3 Periodic inspection
3.9.1. Example - checklist of items that require inspection
The following is a copy of the checklist in Appendix 6 of BS-7671:2008(2011) which lists items at ( various locations within an installation that may require inspection )

 

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Periodic inspection & testing
5.3. Larger and more complex installations the inspector will need to formulate his/her own inspection schedules
5.4. ( x ) Additional forms may be required as clarification . if needed by ordinary persons , or in expansion , for lager or more complex installations

 

[Richard Burns]

(No borrowed neutrals)


GN-3 : 2008 . ISBN 978-0-86341-857-0


2.6.3. Inpection checklist


Listed below are requirements to be checked when carrying out an installation inspection , The list is not exhaustive .





4 ) Circuits to be separated ( no borrowed neutrals ) 314.4.





GN-3 : 2011 . ISBN 978-1-84919-275-0


2.6.3. Inpection checklist


Listed below are requirements to be checked when carrying out an installation inspection , The list is not exhaustive .




5) Circuits to be separated ( no borrowed neutrals ) 314.4.





BS-7671:2001:2008:2011:


P/46 , Where an installation comprises more than one final circuit , each final circuit shall be connected to a separate way in a distribution board , The wiring of each final circuit shall be electronically separate from that of every other final circuit , so as to prevent the inderct energizing of a final circuit intended to be isolated

 

[Richard Burns]

On Rant mode .


GN-3 This Guidance Note is concerned principally with Part 6 of BS-7671: Inspection & Testing Etc
Am asking the (( Question )) What can GN-3 do for you . !!! Help you to pass you're Exams


Periodic testing
GN-3 3.10.2. Test to be made : 621.2.


The tests considered appropriate by the person carrying out the inspection should be carried out in accordance with the recommendations


3.5. Testing to be carried out where practicable on existing installation(s)
see notes 1 & 2


1) The person carrying out the testing should decide which of the above tests are appropriate by using their experience and knowledge of the installation being inspected .
2) Where sampling is applied , the percentage used is at the discretion of the inspector .


Recommendations ... ( Tests )
Protective conductors continuity . Accessories exposed-conductive-parts of current-using equipment & accessories ( notes 4 / 5 )


4) The earth fault loop impedance test may be used to confirm the continuity of protective conductors at socket-outlets and at accessible exposed-conductive-parts of current-using equipment and accessories


5) Generally, accessibility may be considered to be within 3m from the floor or from where a person can stand


- Bonding conductors continuity :
Main bonding conductors to extraneous-conductive-parts
Supplementary bonding conductor


- Ring circuit continuity :
Where there are records of previous tests , this test may not be necessary unless there may have been changes made to the ring-final-circuit


- Polarity :
At the following positions .
• origin of the installation
• distribution boards
• assessable socket-outlets
• extremity of radial circuits


- Earth fault loop impedance :
At the following positions
• origin of the installation
• distribution boards
• assessable socket-outlets
• extremity of radial circuits


- Insulation résistance :
if tests are to be made
between live conductors and earth at main and final distribution boards
6) Where the circuit includes surge protective devices ( SPDs ) or other electronic devices which require a connection to earth for functional purpose , these devices will require disconnecting to avoid influencing the test result and to avoid damaging them .


- Earth electrode résistance :
if test are to be made .
Test each earth rod or group of rods separately , with the test links removed , and with the installation isolated from the supply source .


- Functional tests :
RCDs .. Tests as required by Regulation 612.13.1. followed by operation of the integral test button


Functional tests - of circuit-breakers , isolators and switching devices .. Manual operation to confirm the devices disconnect the supply .


R/P 400 , Inspection schedule , taken at random
4.7. Operation of main switch ( functional check ( 612.13.2. )
4.8 . Manual operation of circuit breakers and RCDs to prove disconnection ( 612.13.2 )
4.15 Single-pole protective devices in the line conductor only ( 132.14.1. ; 530.3.2. )
4.18. RCDs provided for fault protection - includes RCBOs ( 411.4.9 ; 411.5.2 ; 531.2 )
4.19. RCDs provided for additional protection - includes RCBOs ( 411.3.3. ; 415.1. )

 

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2394 .. Initial Verification of Electrical Installations.

Q) from -&-s
Candidates were asked to determine the expected measured values at each stage of a test to confirm ring final circuit continuity.

The candidates were then asked to explain the expected pattern of measured values taken at each socket-outlet when carrying out an earth fault loop impedance test on the circuit.

Some
candidates lost marks because their description was vague and could have been a description for a radial socket-outlet circuit rather than a ring final circuit.

O.S.G. 7.1. Final circuit(s)
Table 7.1. (i) has been designed to enable a ( Radial or Ring-final-circuit ) to be installed without calculation where the supply is at 230V single-phase or 400V three-phase .
For other voltages , the maximum circuit length given in the table must be corrected by the application of the formula : etc

411.3.2. Automatic disconnection in case of a fault .
411.3.3. Additional protection .
525.101. Where fixed current-using equipment is not the subject of a product standard the voltage at the terminals shall be such as not to impair the safe functioning of that equipment . etc

each stage of a test to confirm ring final circuit continuity.

10.3 Test procedures
( 612.2.1. ) .. Testing 10.3.1. Continuity of circuit protective conductors and protective bonding conductors ( ► for ring-final-circuit see 10.3.2. )
( 612.2.2. ) .. 10.3.2. Continuity of ring-final-circuit conductors .

Your Q : !! A Three-step is required to ( verify the continuity of the ) Line , Neutral and Protective-conductors ,
Your Q : ( for the sake of -&-s ) .... Use a low-résistance ohmmeter for this test ............ Yes we all know that we use MFT testers nowadays .

Step 1 .
The line , neutral and protective-conductors are ( identified at ) the distribution board ( in our case here at the Consumer-unit ) and the end-to-end résistance of each is measured separately You're Q , ( see Figure 10.3.2.(i))

You're Q .. Step 1 .
The end-to-end résistance of the line , neutral and protective-conductors are measured separately ... ( initial check for continuity at ends of ring )

Step 2 . The line & neutral conductors are then connected together at the distribution board so that the outgoing line-conductor is connected to the returning neutral-conductor & vice versa . You're Q see Figure 10.3.2. (ii))

Has O.S.G given insight here . refer to
Note : Where single-core-cables are used , care should be taken to verify that the line and neutral conductors of opposite ends of the ring circuit are connected together ... in domestic we use T&E cable . not single-core-cables . with any Q) from -&-s . we can't see the trees from the woods . Yeah .

Figure 10.3.2. (ii) Step 2 . The line and neutral conductors are cross-connected and the résistance measured at each socket-outlet

Step 3 . The above step is then repeated ,
this time with the line and circuit-protective-conductor crossed-connected at the distribution board ( see figure 10.3.2.(iii))

You're Q , The résistance between line and earth is measured at each socket-outlet .

" " The readings obtained at each of the socket-outlets wired into the ring will be substantially the same and the value will be approximately one-quarter of the résistance of the line plus cpc loop résistance . i.e.

" " ( r[SUP]1[/SUP] + r[SUP]2[/SUP] ) / 4 . As before , a higher résistance value will be measured at any socket-outlet wired as ( Spurs )

" " The highest value recorded represents the (( maximum)) ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) of the circuit and is recorded on the Schedule of Test Results .
" " The value can be used to [ determine the earth fault loop impedance ] ( Zs ) of the circuit to verify compliance with the loop impedance requirements of BS-7671: see 10.3.6.

10.3.2. (iii) Step 3 . The line conductors and circuit-protective-conductor are cross-connected and the résistance measured at each socket-outlet
Connection for taking readings of R[SUP]1[/SUP] + R[SUP]2[/SUP] at socket-outlets

This sequence of tests also verifies the polarity of each socket-outlet , Except that where the testing been carried out at the terminals on the reverse of the accessories , a visual inspection is required to confirm correct polarity connections , and dispenses with the need for a separate polarity test .

 

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Accessory
Switches, sockets, ceiling roses etc.

R/P23 . Accessory A device , other than current-using equipment , associated with such equipment or with the wiring of an installation

R/P24 . Circuit
An assembly of electrical equipment (socket outlets, lighting points and switches) supplied from the same origin and protected against over current by the same protective device(s).

 

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On rate mode . O.S.G. refer to

The value can be used to [ determine the earth fault loop impedance ] ( Zs ) of the circuit to verify compliance with the loop impedance requirements of BS-7671: see 10.3.6.

10.3.6. Earth fault loop impedance :
612.9. The earth fault loop impedance ( Zs ) is required to be determined for the furthest point of each circuit . it may be determined by :
► direct measure of ( Zs ) or
► direct measure of ( Ze ) at the origin and adding ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) measured during the continuity test ( 10.3.1. & 10.3.2. ) [ Zs = Ze + ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) ] or
► Adding ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) measured during the continuity tests to the value of ( Ze ) declared by the distributor ( see 1.1. (iv) & 1.3. (iv)

The effectiveness of the distributors earth must be confirmed by a test . etc

What lets us down badly is not understanding the very basics . it's all in books

 

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Please read the Q )

re-cap Inspection & testing .. my point is ( drawings )

Answer
disconnect conductors at a suitable point on the circuit

5 c) Describe how the continuity of the ring-final-circuit test is to be carried out on Circuit 9 once the circuit has been safely insulated and secured .

Step 1
• Test the conductor end-to-end loop résistance
• Record results r[SUP]1[/SUP] , r[SUP]N[/SUP] , r[SUP]2[/SUP]

Step 2 ... Interconnect line of outgoing leg with neutral of incoming leg and line of incoming leg with neutral of outgoing leg .

Step 3 ... Interconnect line of outgoing leg with cpc of incoming leg and line of incoming leg with cpc of outgoing leg
• Test line to cpc at each socket-outlet
• Record highest value as R[SUP]1[/SUP] + R[SUP]2[/SUP]
• Reinstate the circuit

-&- are saying don't waffle on , time is precious in Exams .

Comments ...
Answering these types of questions using bullet point is clear and easy way to see that no part are missed out and that the test is complete .

A drawing may be used in place of the interconnection statements such as :


GN-3 P/37 refer Figure 2.2b . Figure 2.2c . connector block etc

Step 1
cross connect line and neutral ... drawing may be used in Exams

This may be easer that writing the connection descriptions in full . There is no set sequence for step 2 & 3 but all three steps must be detailed in order to score well on this question

Tip : Failure to identify that at each step test are carried out at each socket-outlet will lose several marks .

 

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612.2.2. Continuity : Test be made to verify the continuity of ( each-conductor )
Continuity of ring final circuit conductors including circuit-protective-conductor(s) of every ring-final-circuit must be verified .

if the conductors are the same size
if the protective conductor has a reduced CSA , the résistance of the protective loop will be proportionally higher than that of the line , neutral loop

O.S.G. 10.3.2. / 612.2.2. Three step test is required to Verify the continuity of : ( Step 3 )

Step 3 10.3.2 (iii)
Line-conductors & circuit-protective-conductors ( CPC ) crossed connected .
The résistance between line & earth is then measured again at each outlet , The highest value recorded represents the maximum ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) of the circuit and can be used to determine the earth-loop-impedance ( Zs ) of the circuit .

This test also verifies the polarity at each socket-outlet

 

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Main earthing terminals
MET testing . R/P160

the regulations have stated the facts
As called for in Regulations 542.4.1. & 542.4.2. as MET is required for every installation .

One of the principal purposes of the MET is to provide for disconnection of the earthing-conductor from circuit-protective-conductors and bonding-conductors , So that the external line to earth loop impedance ( Ze ) can be measured .

542.4. Main earthing Terminals or Bars

542.4.2
The means of disconnection must involve the use of a tool .. can be ( Bars / Spanner or Terminals / Screwdriver ) may be provided in the form of a disconnectable link , (( with any connections' to MET providing reliability & continuity ))

Protective Conductor(s)

Including :
Earthing conductor(s)
Circuit-protective-conductor(s)
Main-protective-conductor(s)
Supplementary-protective-bonding-conductor(s) where required

 

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R/P 53 . 411.3.1.2. Protective equipotential bonding

Where an installation is contained in more than one separate building , Regulation 411.3.1.2. calls for a MET .. ( & equipotential bonding ) for each building

411.3.1.2 In each installation :
Main protective bonding conductor(s) shall connect to the main earthing terminal extraneous-conductive-parts including the following :

i) Water installation pipes
ii) Gas installation pipes
iii) Other installation pipework & ducting
iv) Central heating and air conditions systems
v) Exposed metallic structural parts of the building

 

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System earth fault loop impedance ( Zs ) s)) system ..

Earth fault loop impedance ( Ze ) e )) external to the installation .
The external earth fault loop impedance ( Ze ) is one of the supply characteristics to be recorded can only be measured by testing at the origin of the installation .

R/P 390 ( EIC ) supply characteristics . External loop impedance ( Ze [SUP]2[/SUP] ) by enquiry of by measurement . ( direct-measurement )
R/P 397 ( EICR ) supply characteristics . External loop impedance ( Ze [SUP]2[/SUP] ) by enquiry of by measurement . ( direct-measurement )

R/P 31 . Origin of an electrical installation . The position at which electrical energy is delivered to an electrical installation .
R/P 32 . Origin of temporary electrical installation . Point on the permanent installation or other source of supply from which electrical energy is delivered to the temporary electrical installation . refer GN-3 P/53 Zs = Zdb + ( R[SUP]1[/SUP] +R[SUP]2 [/SUP])

Direct measurement : -&-s
This indicates that a test is required and the results are not to be established by using a calculation . for example , where you are asked to describe the direct measurement of earth fault loop impedance , then a description of the test procedure is required , Describing an R[SUP]1[/SUP] +R[SUP]2 [/SUP]test and then stating how to determine the value by calculation using Zs = Ze + ( R[SUP]1[/SUP] +R[SUP]2 [/SUP]) will result in on marks being awarded for the answer

2394 : -&-s Q) Which of the following is not a method for determining prospective-earth-fault-current at the origin of an installation ?
A) Calculation using the measured Zs and the supply voltage .

( Ipƒ ) Prospective fault current is measured to determine the maximum fault current which may occur , Any impedance measurement taken at the end of a circuit will be higher than that at the origin of the circuit , As a result the value obtained from the calculation is not going to produce the maximum value .

 

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• O.S.G. Table 11 - 2.5mm[SUP]2[/SUP] / 1.5mm[SUP]2[/SUP] cable has a résistance of 19.51mΩ per metre
The résistance of 54 metres is : 54 x 19.51 / 1000 = 1.05Ω , 1.05 ÷ 4 0.26Ω

R[SUP]1 [/SUP]+ R[SUP]2 [/SUP]for the circuit is 0.26Ω
Zs = Ze + R[SUP]1 [/SUP]+ R[SUP]2 [/SUP]0.24Ω + 0.26 = 0.5Ω

• An installation has seven circuits . Circuit 1 . 4 . 6 have insulation résistance of greater than 200MΩ
Circuit 2 .3 . 5. & 7 . have résistance values of 50 . 80 . 60 . 50 , Calculate the total résistance of the circuit .

1 ÷ 50 = 0.02 , 1 ÷ 80 = 0.0125 , 1 ÷ 60 = 0.016666666 , 1 ÷ 50 = 0.02 :- 0.02 + 0.0125 + 0.016666666 + 0.02 = 0.069
1/50 + 1/80 + 1/60 + 1/50 = 0.069 .. R = 1 ÷ 0.069 = ****Ω

 

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( little rs & Big Rs )
You will not be the first to fall short at understanding the little rs & big Rs
R/P 402 : Schedule of test results . Ring final circuit continuity ( Little rs 10 , 11 , 12 )
Big Rs , Continuity Ω ( R[SUP]1 [/SUP]+ R[SUP]2 [/SUP]) 13* , * Where there are no spurs connected to a ring final circuit this value is also the ( R[SUP]1 [/SUP]+ R[SUP]2 [/SUP]) of the circuit

( Little rs 10 , 11 , 12 ) r[SUP]1[/SUP] , r[SUP]N [/SUP], r[SUP]2[/SUP] , are the end-to-end ring final circuit readings
R[SUP]1[/SUP] ) is the maximum résistance of the line-conductor for a circuit .
R[SUP]2[/SUP] ) is the maximum résistance of the circuit-protective-conductor for a circuit
( R[SUP]1 [/SUP]+ R[SUP]2 [/SUP]) is the test reading value of the two-resistances added together
( R[SUP]1 [/SUP]+ R[SUP]N [/SUP]) is done to help confirm polarity so does not need recording

Note : that spurs from the ring-final-circuit will give higher readings

 

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At random . Q/As word for word .

2394 & 2395 Inspection & Testing
Section B :
Remember that the answers to the following questions must relate to the scenario contained in the Source Document .

Q) Describe how a test is carried out to determine the prospective fault current at the origin of the installation by direct measurement
A) Secure the area around distribution board
Access incoming live terminals
Using a PFC tester ( or EFLI tester set to kA )
Confirm test leads comply with GS-38
Connect to incoming supply side Line & Earth
Measure PEFC
Connect it incoming supply side Line & Neutral
Measure PSCC
Record highest result as the PFC
Reinstate the DB

▼▼▼▼▼ There may be improvement in the 18th Edition here GN-3
C) In the case there have been no previous questions relating to the preparation such as type of instrument etc. and so this information needs to be included in the answer. ◄◄ Your Q )

Tip . Failure to identify that the test leads must comply with GS-38 will lose several marks . It is vital to remember that the earthing and all protective bonding conductors are connected whilst this test is carried out .

( Ipƒ ) 612.11. Prospective fault current
Regulation 612.11. requires that the prospective fault current under both short-circuit and earth-fault conditions be measured , calculated or determined by another method , at the origin and at other relevant point in the installation .

GN-3 . 4.5. Instruments conforming to BS-EN-61557-3 will fulfil the above requirements
These instruments may also offer additional facilities for deriving prospective fault current . The basic measuring principle is generally the same as for earth fault loop impedance testers . ETC . refer

GN-3 4.5. Earth fault loop impedance testers .
These instruments operate by circulating a current from the line conductor into the protective earth , This will raise the potential of the protective earth system

To minimise electric shock hazard . etc This means that the instrument should cut off the test current after 40mS Etc refer

 

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BS-7671:2008:2011: Voltage-drop PS I will not type this out again

612.14. Verification of voltage drop
Where required to verify compliance with Section 525 , the following options may be used .
i) The voltage drop may be evaluated by measuring the circuit impedance .
ii) The voltage drop may be evaluated by calculations , for example , by diagrams or graphs showing maximum cable length v load current for different conductor cross-sectional areas with different percentage voltage drops for specific nominal voltages , conductor temperatures and wiring systems .

Note : Verification of voltage drop is not normally required during initial verification .

Written Examination 2395-302 Read the Qs) Good luck in Exams

Q/As 3 a) i)
Q) Explain the cause of voltage drop within an installation ( 3mk )
A) Volt drop is a product of the conductor resistance and the load current .
Com) The question refers to voltage drop that occurs normally within the installation which is caused by the conductor résistance and the current flowing , Do not confuse this with the causes of excess voltage drop due to poor design or overloading of the circuit

3 a) ii) State the two methods of determining voltage drop ( 2mk )
A) Measurement & Calculation
[h=4]Com ) it is not acceptable to carry out a direct measurement of voltage drop using volt meter(s) The circuit conductors must be at their normal operating temperature , the circuit under full load and there must be no variation in the supply voltage during the test , The methods given are as a result of the measurement of conductor résistance and the reference to charts or tables giving the details of voltage drop . These are not the figures in tables in Appendix 4 of BS-7671: which are generic design details for the calculation of appropriate cable sizes .[/h]
3) b) i) A radial circuit has a load current (Ib) of 28A at 230V ac and has a combined live-conductor résistance of 0.16Ω at 20°C .
Determine the voltage drop for this circuit , Show all calculations' ( 5mk )

A) Voltage drop = ( R[SUP]1[/SUP] + R[SUP]N[/SUP] ) x Ib x 1.2
So Voltage drop = 0.16 x 28 x 1.2 = 5.376V
Com ) The use of the conductor résistance and load current together with the 1.2 multiplier to compensate for the difference in conductor temperature at the time of test and the normal operating temperature of the conductors when maximum résistance and hence maximum voltage drop will occur .

3 b) ii ) if the radial circuit supplies a machine lathe , determine whether the voltage drop in b (i) above complies with BS-7671: ( 5mk )
A) Maximum volt drop - 230V x 5% = 11.5V ......... As 5.376V is equal to or less than 11.5V so complies

Com ) Alternative calculations such as : max voltage drop = 5% V drop = 5.376 ÷ 230 x 100 = 2.3% which is less than 5% So Ok
may be used and will attract the same marks .

(( 5.376 ÷ 230 = 0.023373913 x 100 = 2.3% ))

Tip . It is important to show the calculations because in this type of question where an error is made in the calculation candidates are only penalised once for the error .
The remainder of the answer is marked based upon the incorrect figure produced and , providing the process is correct , marked accordingly , Candidates could have completely the wrong answer for 3 b (i) but based upon their incorrect figure from that calculation achieve full marks for 3 b (ii ) providing their calculation and conclusion is correct .

GN-3 P/59 2.7.20. Verification of voltage drop . Section 525 .
612.14. Where it may be necessary to verify that voltage drop does not exceed the limits stated in relevant product standards of installed equipment BS-7671 : provides two options to do so , Where no such limits are stated , voltage drop should be such that it does not impair the proper and safe functioning of install equipment .

Voltage drop problems are quite rare but the inspector should be aware that long runs and / or high currents can sometimes cause voltage drop problems .

refer to GN-3 .

 

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Chief Examiners report - Questions relating to voltage drop also caused difficulty for many candidates

Knowledge of BS-7671 and Guidance Note 3
Questions relating to voltage drop also caused difficulty for many candidates. Many candidates were unable to correctly state the cause of voltage drop in a circuit. A large number of the responses indicated that voltage drop only occurred as a result of poor design giving undersized cables and heavy loads as typical answers. A great many failed to identify that voltage drop is the product of conductor resistance and load current.

Candidates were given information related to a particular circuit and asked to determine i) the expected voltage drop and ii) whether this value complies with the requirements of BS-7671. Many candidates failed to make any allowance for the change in conductor temperature when calculating the expected voltage drop. When determining compliance a large number of candidates failed to indicate why their conclusion was compliant or non-compliant.

 

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2395-303 .. Read the Q) carefully

Chief Examiners report -

Very few candidates were able to explain why the sequence of tests for a periodic inspection may be different from that given in BS 7671 for initial verification. The majority of candidates confused this with the limitations agreed for the periodic inspection. Whilst this can affect the tests carried out, some being omitted, it does not affect the sequence of testing.

What's is the difference between :

Periodic inspection .
Initial verification .

1 d ) Explain why the sequence of testing for the periodic inspection may be different to that given in BS-7671: for initial verification

A) The installation has been inspected and tested and placed in service. Periodic inspection verifies the current condition or the safety of the installation and not the confirmation of the safety of the installation before placing in service .

Com) The candidate needs to explain the purpose of the periodic inspection and how this differs from (( Initial Verification ))
All these tests could be carried out at periodic inspection but not necessarily in the same sequence , The answer needs to clarify why this is the case .

GN-3 P/66 3.8 Requirements for inspection and testing .
Extracts
621.2. The requirement of BS-7671: for periodic inspection and testing is for a detailed inspection comprising an examination of the installation without dismantling or with partial dismantling as required , together with the tests of Chapter 61 considered appropriate by the person carrying out the inspection and testing , The scope of the periodic inspection and testing must be decided by a competent person , taking into account the information contained in this section .

3.1. Periodic inspection and testing
621.2. The purpose of periodic inspection and testing is to provide an engineering view on whether or not the installation is in a satisfactory condition where it can continue to be used safely

GN-3 P/67
Extracts : For safety . it is necessary to carry out a visual inspection of the installation before testing or opening enclosures , removing covers etc . So far as is reasonably practicable, the visual inspection must verify that the safety of persons , livestock and property is not endangered

 

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Chief Examiner . has made some comments

2394 / 5
The inspection process is a vital part of the periodic inspection process , many conditions may be indentified during the inspection which would not be revealed by testing alone , Candidates are expected to be aware of the areas to be inspected , the actual items to be checked and the human senses to be used whilst inspecting those items . Recording the outcome for each inspection item is also a requirement of the reporting process

Candidates should be aware that the (( Schedule of Inspections )) for the periodic inspection of installations provided in BS-7671: and IET GN-3 together with the examples of items requiring inspection given in BS-7671: Appendix 6 , provides detailed information on the items of inspection for these installations , Candidates should become familiar with the items they are to consider , inspect and record and this will greatly improve both their understanding of the inspection process and their success in any related questions

 

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Confirmation of compliance

Confirmation of compliance of the installation with the requirements of BS-7671: forms part of the periodic inspection process , The source document generally identifies that all testing is carried out at an ambient temperature of 20°C :willy_nilly:

This means that test value will not be at normal operating temperature and so this must be considered and where necessary compensated for .

 

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Written Exams . 2395-
Principles , practices and legislation for the periodic inspection of electrical installations ◄◄◄

In this paper you will often be asked to provide longer answers for questions that ask you to " describe " or " explain " These are often related to inspection and / or test procedures and you are required to demonstrate your knowledge of the inspection and / or test process .
There is no such indication for this question and so the requirements must be included and so you will need to include obtaining permission and the isolation procedure in your description

For example :
Describe , in detail , the procedure for carrying out a test to confirm the continuity of the main protective bonding conductor connected to the water installation pipework ( 10mk )

There are a number of points in this question , The answer is worth 10 marks and the question asks for " detail " so a full description is required

As this examination only considers periodic inspection , you can determine that the installation is energised , You would always need to confirm that it is safe to isolate the installation or circuit and state that safe isolation is carried out . On occasions the question may state that the permission to isolate has been given or safe isolation has been carried out .

Such questions may also be preceded by a number of auxiliary questions relating to the actions required before or after the test concerned , In such cases these items would not need to be repeated in the procedure .

There is no such indication for this question and so the requirements must be included and so you will need to include obtaining permission and the isolation procedure in your description .

Option 1. ◄
Description of the process in a " Story format " :30:

" I would obtain permission from the client to isolate the installation , carry out safe isolation of the whole installation , lock off and retain the ( unique key ) I would then disconnect one end of the main protective bonding conductor . I would select a low résistance ohmmeter , check condition and function , select a suitable long test lead and null the test leads , I would connect one test lead to the disconnected main protective bonding conductor and the other lead to the far end of the conductor , Test and record the results , I would then reconnect the main protective bonding conductor before reenergising the supply "

This answer and similar variations are perfectly acceptable and you would obtain the marks for the question , However , it does rely on the procedure being written down correctly the first time without missing any steps . it involves a considerable amount of writing and it is often difficult to spot any errors during the examination when you read back through your answer .

 

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Re-cap Describe , in detail , the procedure for carrying out a test to confirm the continuity of the main-protective-bonding-conductor . Etc

Option 2 ◄
The answer can be structured as a set of ( Bullet points ) as follows

- Obtain permission to isolate the supply
- Safety isolate , lock off and retain the key ..................... " lock off and retain the ( unique key ) "
- Disconnect the main protective bonding conductor at one end
- Select a low résistance ohmmeter , check condition and function
- Select a suitable long test lead
- Null the test leads
- Connect the test leads to the disconnected bonding conductor and the far end
- Test and record the results
- Test and record the result
- Reconnect the main protective bonding conductor before reenergising the supply

There is plenty of space to write down your answer , so you can leave space between each bullet point , giving you the opportunity to add an additional line in later if you have missed a step in the process , You can also read through your answer muck quicker and identify any omissions

Additional bullet points may be added at the end if you find you have missed out some information providing they identify when the action is carried out . for example if you find you have omitted to null the test leads the final bullet point could be added as :

- Before carrying out the test the test leads should be nulled

This would then ensure that the appropriate marks are awarded for your answer .

Continues .

 

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Continues . 2394 / 5 ........... Exams , Time is precious Waste it Wisely . PASS :icon_bs:

Re-cap Describe , in detail , the procedure for carrying out a test to confirm the continuity of the main-protective-bonding-conductor . Etc

The second option , with the use of the bullet points , is generally quicker to comply , less prone to errors or omissions and clearly demonstrates your understanding of the test process , You can try both methods to find out which best suits you . However , Option 2 is strongly recommended .

it is important to recognise the need to carry out testing in a way that does not put yourself or anyone else at risk . Also the test must be carried out in such a manner that produces valid results ,. No marks will be awarded for an answer that describes dangerous techniques and a heavy penalty will be applied to answers that describe invalid procedures

 

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Just some Facts : Sample Test 2395-302 :mad2:

Principles , practices and legislation for periodic inspection , testing and condition reporting of electrical installations .
Periodic inspection , testing and condition reporting .

You should have the following for this assessment :
non-programmable calculator
a pen with black or blue ink
drawing instruments
one enclosed source document

General instructions
• This examination consists of six structured questions , Candidates must answer all six questions :
• Section A - three structured questions , each carrying 15 marks
• Section B - three structured scenario-based , questions each carrying 15 marks
• The terminology used in answering this paper should be in accordance with current IET Publications
• Show all calculations . if you use a calculator , show sufficient steps to justify your answers
• Write all your working out and answers in this booklet

Example .
Section A - All questions carry equal marks . A) all three questions . Show all calculations'
1) The electrical installation in a craft workshop is scheduled for a periodic inspection and test for insurance purposes

a) State two statutory documents which apply to the inspection may need to refer to relating specifically to inspection and testing

i) The questions in Sample test 2395 are repeated below with sample answers , and comments and advice where appropriate .
i) The electrical installation in a craft workshop is schedule for a periodic inspection and test for insurance purposes .

a) State two statutory documents which apply to the inspection and testing process .
A)
Electricity at Work Regulations
Health and Safety at Work Regulations ( etc ) .......... What not to write Act

Com ) Abbreviations such as EWR and HSWA are acceptable . Candidates must correctly identify whether these are an Act or Regulations in order to achieve the marks

1 b) State three non-statutory documents which the inspector may need to refer to relating specifically to inspection and testing
A)
BS-7671:
On-Site-Guide
Guidance Note 3

Com) GS-38 is an acceptable alternative so any three from these four are acceptable . Abbreviations such as . O.S.G. and GN-3 are also acceptable answers . As the question asks for three items , the examiner will only mark the first three responses

1 c) State who the inspector will consult to establish the extent and limitations of the periodic inspection and test .
A)
The client
The insurance company

Com ) The person ordering the work or the person requiring the work are acceptable alternatives to the client . Note : Read the question carefully , the main question stem specifies that the work is for insurance purposes

The response must relate to the insurance company and so other interested third parties or any other specific third party such as licensing authority etc . will not receive a mark .

 

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Written Exams 2394-302:

Please read the question , PS this has been downloaded for a Reason . Making you aware :30:

This has got my attention Q/As

Section B
State the document to be completed by the inspector and given to the client on completion of the inspection and test

A) Electrical Installation Condition Report or EICR , Schedule of Inspections , Schedule of Test Results

Com )
These are the requirements identified in BS-7671: ............ Electrical Installation Condition Report or EICR , Schedule of Inspections , Schedule of Test Results

These are the requirements identified in BS-7671: Tiles used on the Standard Forms such as generic schedule of test results and Condition Report Inspection Schedule would also be acceptable

Your Q ) What not to do , Schedule of Tests , Schedule of items tested etc Will Not Attract Marks

 

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Exam Success - Inspection & Testing 2394 & 2395 .

Section B
Remember that the answers to the following questions must relate to the scenario contained in the source document .

4 ) a) The loop length for the office ring final circuit is 60m and all the socket-outlets are connected directly into the ring . Determine showing all calculations' .

i) the expected R[SUP]1[/SUP] + R[SUP]2[/SUP] test value
A) r[SUP]1[/SUP] + r[SUP]2[/SUP] = 60 x ( 7.41 + 12.10 ) 1000 = 1.17Ω

R[SUP]1[/SUP] + R[SUP]2[/SUP] = 1.17 / 4 = 0.293Ω

Com ) There is more than one way to determine this value but any correct method would be given the marks . The use of a temperature correction factor in this calculation is not appropriate because the question asks for an expected " test " value and the Source Document states that testing is to be carried out at 20°C , which is the same temperature as that which applies to the mΩ/m values in Figure 2 .

The calculation could have also been laid out as shown below

r[SUP]1[/SUP] = 60 x 7.41 / 1000 = 0.446Ω
r[SUP]2[/SUP] = 60 x 12.10 / 1000 = 0.726Ω
R[SUP]1[/SUP] + R[SUP]2 [/SUP] = 0.446 + 0.726 / 4 = 0.293Ω ... ( 0.446 + 0.726 = 1.172 ÷ 4 = 0.293Ω )