Re-take - Useful Information for 2394 :

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Test 3 ,

Section A .. Q/As PS this one has my full attention.

The questions in sample test 2394-302 are repeated below with sample answers , and comments and advice where appropriate .

1 c ) State what must be verified when inspecting electrical equipment , during an initial verification .

A)
Equipment is to British Standards
Equipment is correctly selected and erected
Equipment is not damaged

Com ) The question refers to the inspection of electrical equipment and NOT to the inspection . BS-7671: refer specifically to what must be verified when inspecting electrical equipment .

((( Equipment is installed to the requirements of BS-7671: ))) is an acceptable alternative to ((( correctly selected and erected ))) as this is a requirement of The Wiring Regulations . it is NOT an acceptable alternative to ((( Equipment is to British Standards ))) but reference to European or International standards’ would also be acceptable .

 

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Test 4

Section A

The questions in sample test 2394-302 are repeated below with sample answers , and comments and advice where appropriate .

2 c ) List two labels that would normally be present on a newly completed domestic installation

A) :30:
Next inspection notice .
Earthing and bonding notice .

Com) The key word in this question is ((( normally ))) The examiner is looking for labels that are ((( normally ))) present on a new domestic installation . Answers that include labels that , under certain conditions are present , but are not ((( normally ))) present would not be acceptable .

Again , because the question has asked for two answers , only the first two answers given by the candidate would be considered .

An RCD notice would also be an acceptable answer .

 

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Section A
The questions in sample test 2394 & 2395 are repeated below with sample answers , and comments and advice where appropriate .

3 c ) (i) List the measurements to be taken , at the main switch of a three-phase TN-S system , in order to determine the installation prospective fault current ( Ipƒ )

A) :30:
L1 to L2
L1 to L3
L2 to L3

Com ) There is no need to carry out any other tests to determine ( PFC ) because on a three-phase system the largest fault current will be due to a symmetrical short-circuit , that is a short-circuit between all line conductors at the same time . A test between line conductors is an acceptable approximation . if additional tests were included in the answer then this would not make the answer invalid .

The measurement of L1 to N , L2 to N and L3 to N would be an acceptable Alternative method ( see answer 3 c (ii) below

3 c (ii) Explain how the recorded value of prospective fault current ( Ipƒ ) is determined following the test in c (i) above

A ) The highest value of the three measurements :30:

Com ) 3 c (i) and (ii) are linked and the answer to (ii) is dependent on the test method used in (i) if the answer to (i) was to measure between L and N then this answer would be ((( the largest value x 2 ))) if the answer to (i) included tests to earth then this answer must state ((( the largest line to neutral value x 2 )))

 

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-&-s Guidance on Sitting the e-vole multiple choice examination

Effective methods of answering questions

In order to have the best chance of success it is essential to read the question carefully and make sure you understand what is being asked . The answers provided will include one correct answer and understanding the question is key to selecting the right response .

Based on their experience candidates sometimes believe that the answer they want to give is not included in the choices .
In such instances the best approach is the consider the options given and select the one which is most appropriate for the question .:30:

One of the key features of the system is the ability to flag a question where you are unsure of the answer .
This is registered by the system and a flag indicator is placed next to the question .
This allows you to identify and return to flagged questions at any time during the exam .

 

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Wording of Questions :6:

Direct measurement
This indicates that a test is required and the results are not to be established by using a CALCULATION . :13:

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 starting how to determine the value by calculation using Zs = Ze + ( R[SUP]1[/SUP] + R[SUP]2[/SUP] ) will result in no marks being awarded for the answer .

 

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State : Don’t go overboard with the word (( State )) ▼ ▼ ▼ Please read the Q ) :30:

This means the answer is expected to be a short statement, not a long or rambling paragraph.
The response to this type of question may even be just a single word or group of words which may not need to be a complete sentence .

Example .. (( just a single word )) (( group of words ))

1 a (iii) State the title given in law to the inspector whilst carrying out the inspection of an electrical installation
A) Dutyholder ... (( just a single word ))

Com) This question refers to the requirements of The Electricity at Work Regulations and the term (( Dutyholder )) refers to anyone having a duty of care to others .

5 a (ii) State the document that specifies the requirements for the test leads .
A) Leads to GS-38 . .... (( group of words )) PS This is not rambling paragraph.

2 a (ii) State the test voltage to be applied for the insulation résistance test .
A) 500 volts ... PS This is not rambling paragraph.

2 a (iii) State the effect on the value of insulation résistance produced by cable length .
A) As length increases résistance decreases ... PS This is not rambling paragraph.

Com ) An alternative answer includes as length decreases résistance increases .
Alternative terms such as higher or lower are acceptable .

 

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List : Don’t go overboard with the word (( List )) ▼ ▼ ▼ Please read the Q ) :30:

This means you should produce (( a simple list of items (( or )) actions ))

The answer should be similar to that produced for the “ state “ question , However , on this occasion the items would be expected to follow a sequence and form a (( List )) is used to indicate this requirements .

Example ..

2 c ) (( list )) two labels that would normally be presented on a newly completed domestic installation .

A )
• Next inspection notice
• Earthing and bonding notice Etc

1 d ) (( List )) five characteristics of the supply which must be recorded on an Electrical Installation Certificate .

A)
• Earthing arrangements
• Number and type of live conductors
• Nominal voltage
• Nominal ƒrequency
• PFC

Com) Because the question has asked for five answers , only the first five answers given by the candidate would be considered .

:svengo: Acceptable answers must be those characteristics that are recorded on an Electrical Installation Certificate under the heading “ Supply characteristics and Earthing Arrangements “

“ Type of earthing “ , “ external earth fault loop impedance “ , Ze “ , “ ac/dc “ , “ Nature of supply “ would gain a mark but only is none of the other answers given by the candidate included items from that section .

“ Protective device “ , “ main fuse “ and “ earth loop impedance “ would not score marks because they are VAGUE .

 

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Explain : Don’t go overboard with the word (( Explain )) ▼ ▼ ▼ Please read the Q ) :30:

We are not Story telling here . :svengo:

Explain briefly : This requires a brief explanation ; (( usually no more than one or two sentences )) it does not require paragraphs of explanation and the word (( briefly )) is used to indicate this requirement .

3 a ) Explain , in detail , why an earth fault loop impedance test would need to be carried out an existing circuits after the changing of a consumer unit within a domestic installation .

A) Existing circuit protective devices have been removed and new protective devices have been fitted . The characteristics of the new devices are likely to be different from previous devices . Therefore it must be confirmed that the earth fault loop impedance is low enough so that the required disconnection times will be MET .

Com ) The question asks for an explanation (( in detail )) so the description needs to be comprehensive if full marks are to be awarded , Answers that referred to disconnection and re-connection of conductors and the reliability of those connections would score marks .

3 b (i) Explain : why the earthing conductor in an installation must be disconnected from the MET when measuring Ze
A) To remove parallel earth paths so that the intended fault path can be confirmed to be reliable

Com ) if the parallel earth paths are not removed during the test then the reliability of the test result is in DOUBT .

3 b (ii) Explain : why the earthing conductor is connected to the MET when measuring prospective earth fault current .
A ) This is the condition that exists at the time of a fault and therefore is the only way to determine the maximum fault current to earth when carrying out the test .

Com) In this case the purpose of the test is to determine the maximum prospective earth fault current . This will occur when the installation is energised and all earthing arrangements are in place , so the test must be carried out under these conditions .

 

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Please read the Q ) carefully Q/As :30:

Describe :
These questions often relate to test procedures and you are required to demonstrate your knowledge of the test process . Look at the number of MARKs available to give you an indication of how much detail you need to go into .

Describe , in detail :
This indicates that a more detailed answer is required and again the number of MARKs available for the question gives an indication of the depth of the answer required

A series of short bullet pointed statements is a very effective method of providing an answer , but remember that all necessary information must be included

Section B ... Extracts for the Source Document
Remember that the answers to the following questions must relate to the scenario contained in the Source Document .. Extracts for the Source Document

5 ( a ) i , ii , iii .

5 ) The circuit for the three phase saw bench is installed to the local isolator for the saw .
a) A test of earth fault loop impedance is to be carried out on the saw circuit .
:→ i) State the test instrument to be used .
A ) Use an earth fault loop impedance tester

5 a (ii) State the document that specifies the requirements for the test leads
A) Leads to GS-38

5 a (iii) Describe : in detail , how the test would be carried out
• Supply on
• Local isolator off
• Access live terminals in the local isolator
• At the incoming terminals of the local isolator test
o L1 to isolator earthing terminal
o L2 to isolator earthing terminal
o L3 to isolator earthing terminal
• Close the local isolator cover
• Record highest result

Com ) The structure of this question is intended to help the candidate identify all relevant information .

A list has been used to answer a ) iii) because it is easy to write down , easy to check and time efficient . Each statement must include sufficient information to make it clear how the test would be carried out . it is not necessary to include the instrument title and lead requirement as part of this answer as they have already been identified in i) and ii) above

This test is carried out between each line conductor and the isolator earthing terminal . if a candidate described the isolator earthing terminal as “ the earthing terminal “ , “ earth “ , or “ the cpc “ this would also gain the marks .

If the wrong test was described in the answer , such as R + R test and the results is then added to Ze , then no marks would be awarded . The question specifically asks for an earth fault loop impedance test and not any test method that could be used to determine Zs

Answers that include dangerous procedures would score zero marks :13:

 

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This is You’re Q ) :30:

Consider the number of marks available for the question or part-question . This provides a valuable indication of the depth of the answer required
a question which carries one mark will require a much simpler answer than one for which fifteen marks are available .

Take a little longer to read the question carefully to ensure you are quite clear about what is required

Structure of the Exam

Each paper is divided into two sections, Section A and Section B.

Section A of each paper has three questions which are often divided into a number of parts ( a , b , c , and i) ii) iii) and so on ) with each part of the question relating to a different leaning outcome . The number of marks available for each part of the question is shown on the paper and this can be used to indicate how long to spend on your Answer .

Section B also has three questions, but these relate to the scenario contained within a “ Source Document “
These questions may also be divided into parts but often relate to a single learning outcome .

Candidates are expected to display an in-depth knowledge of the particular subject . Typical examples include describing a test-procedure or evaluating test-results.

Show all Calculations :

Again the examiner is trying to help you score as many marks as possible . Where a calculation is required and the only thing offered by the candidate is the numerical answer , then if it is wrong , the candidate would score no marks . if the candidate includes each step of the calculation then marks will be awarded for each correct step . it is always in your best interest to show all stages of the process .

Exam conditions you are under pressure . ... little longer to read the question
Where relevant , remember to show the applicable units which apply to your answer . e.g. V , Ω , kA . etc

Take your Q from this . Written Exams . What can go Wrong in my Q/As :wink_smile:

You are expected to be able to describe the procedures for carrying out activities . ( INCLUDING ) the inspection and testing of installations and circuit’s ( Take your Q ) ►►► These descriptions should follow the format given in IET Guidance Note 3

▼▼▼▼▼ learn by mistakes’
Common errors when answering questions that relate to the scenario are :

• not obtaining permission for isolation or for testing to proceed
• no isolation procedure mentioned when it is appropriate
• no instrument and lead check carried out
• incorrect procedures described , such as not being able to describe the ((( three steps in IET Guidance Note 3 ))) for ring-final-circuit continuity
• not describing the test process in the correct sequence
• failure to consider the safety aspects necessary for the testing process
• failure to reinstate the installation safety once testing is complete
▼▼▼▼▼ learn by mistakes’
Common errors .
A common area for error is the application of the ((( rule of thumb ))) to the maximum tabulated values of earth-fault-loop-impedance ( these maximum values will be given in the scenario or question information ) in order to compare these with the measured values . When candidates do not correctly apply the ((( rule of thumb ))) , it shows they are unable to correctly identify compliance with BS-7671: and therefore no marks are awarded .

 

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▼▼▼▼▼ learn by mistakes’
Common errors when answering questions : :30:


((( No instrument and lead check carried out ))) The full monty Q/As ..Please read the Questions , -&-s will obviously , designed to trap the unwary :icon_bs:

((( lead check carried out )))
((( No instrument check carried out )))

Q) Which publication specifically indentifies the requirements for (( test leads and probes )) to be used when carrying out tests at 230V a.c.
• a) BS-7671:
• b) HSE Guidance GS-38 ***
• c) Electricity at Work Regulations
• b) Provision and Use of Work Equipment Regulations

Q) Test instruments should be calibrated in accordance with the manufactures’ instructions to ensure accurate test results . In addition to calibration which of the following should be carried out and recorded .
• a) Regular confirmation of the instrument’s compliance with BS-7671:
• b) Extension of the instrument warranty period
• c) Regular instrument accuracy checks ***
• d) Closed circuit voltage checks

Com) Regular instrument accuracy checks are required to ensure the instrument continues to ((( provide accurate results ))
Your Q ) ► As identified in GN-3 , 4.2. if regular checks are not carried out it may result in the need to re-inspect and test earlier installations , once an instrument defect is identified .

Q) Which of the following is the maximum voltage above which test leads must comply with the requirements of GS-38
• a) 25V a.c.
• b) 25V d.c.
• c) 50V a.c. ***
• d) 50V d.c.

Com) Where the test voltages are (( ≤ 50V a.c. )) the requirements for GS-38 compliant leads is not necessary where the short-circuit fault current is unlikely to cause a high energy flashover . Test current for this test is (( ≥ 200mA ))

Q) Which of the following requirements from GS-38 applies to test equipment which requires more than one test lead .
• a) The leads must be at least in in length
• b) The leads must have a csa of at least 1.5mm[SUP]2 [/SUP]
• c) The leads must be colour coded for identification ***
• d) The leads must be permanently attached to the instrument

Com) Item ( c ) is the only one the listed items described in ((( GS-38 )))

 

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Show all Calculations : :45:

Again the examiner is trying to help you score as many marks as possible . Where a calculation is required and the only thing offered by the candidate is the numerical answer , then if it is wrong , the candidate would score no marks . if the candidate includes each step of the calculation then marks will be awarded for each correct step . it is always in your best interest to show all stages of the process .

Extracts :

Section B : Source Document
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 .. ( using you symbols’ Ω )
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

The calculation could have also been laid out as shown below

Extracts .

r[SUP]1 [/SUP] = 60 x 7.41 / 1000 = 0.445Ω .. ( using you symbols’ Ω )
r[SUP]2[/SUP] = 60 x 12.10 / 1000 = 0.726? .... PS. What have I left out !
R[SUP]1[/SUP] + R[SUP]2 [/SUP] = 0.445 + 0.726 / 4 = 0.293? .... PS. ^^^

Confirm of Compliance :

Some questions are intended to establish your ability to confirm that measured test results meet the requirements of BS-7671: In order to do this you will be expected to show what steps are taken for this process and any calculations that may be involved . You will also be expected to indentify appropriate action for any situations where the results do not meet the requirements . This will be different for initial verification ( 2394 ) compared with periodic inspection ( 2395 )

 

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Written Examination 2395-

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

Be able to test electrical installations prior to them being placed into service .

You are required to be able to :
Select the test instrument and their accessories for test to include :
Continuity
Insulation résistance
Polarity
Earth electrode résistance
Earth fault loop impedance
Prospective fault current
RCD operation
Phase sequence
Functional testing

Carry out tests in accordance with BS-7671: and IET Guidance Note 3
To include :

Continuity including
o main protective bonding conductor(s)
o circuit protective conductor(s)
o ring final circuit(s)

Insulation résistance
Polarity
External earth fault loop impedance ( Ze )
System earth fault loop impedance ( Zs )
Prospective fault current
RCD operation including additional protection
Phase sequence
Functional testing

Confirm compliance by verifying test results
Complete appropriate documentation in accordance with the BS-7671: and IET Guidance Note 3 including :

• Electrical Installation Certificate
• Schedule of Inspections
• Schedule of Test results ... Generic Schedule of Test results

 

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2395-

Outcome 6 - Understanding the requirements for testing before circuits are ((( Energised )))

You are required to be able to :
State why it is necessary to verify the continuity , to include:
Protective bonding conductor(s)
Circuit protective conductor(s)
Ring final circuit(s)

State the methods for verifying the continuity , to include :
Protective conductor(s)
Ring final circuit(s) conductors
Explain the factors that effect conductor résistance values
Specify the procedures for completing insulation résistance testing
State the effects on insulation résistance values that the following can have :
• Cables connected in parallel
• Variations in cable length

Explain why it is necessary to verify polarity
State the procedures for verifying polarity

Outcome 7 - Understanding the requirements for testing ((( Energised installations )))

You are required to be able to :
Include:
• Installations forming part of a TT system
• generators and transformers

Describe common earth fault loop paths
State the methods for verifying protection by automatic disconnection of supply
Identify the requirements for the measurement of prospective fault current
Specify the methods for determining prospective fault current
Verify the suitability of protective devices for prospective fault current
Specify the methods for testing the operation of residual current devices

State the reasons for verifying phase sequence
State the methods used to verify phase sequence
Describe the methods used to verify voltage drop
State the cause of voltage drop in an electrical installation
Determine voltage drop
State the need for functional testing
Identify items which require functional testing
State the appropriate procedures for dealing with clients during the periodic inspection process

 

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2395-

Outcome 4 – Understanding the difference between peridic inspection and initinal verification .

You are reqiured to be able to :

State the reasons for requiring a periodic inspection as identified in IET Guidance Note 3
State the need to determine the Extent and Limitations of a periodic inspection with the client and intersted third parties before work begins
Explain the application of sampling when carrying out periodic inspection and testing to include :

Factors which determine the extent of sampling
Situations where sampling may not be appropriate

Indentify the need to record agrement with the client and thiord parties on the condition report
Explain the reasons why testing may be undertaken in a diffrent order to that identified in BS-7671: for initinal verification
Indentify the considerations which need to be made during a periodic inspection to ensure the safety of the persons and livestock on the premises
State the purpose of the observations and classification codes in regards to :

• The observations to be recorded
• Appropraite recommendations to be made

State the action to be taken if a dangerous situation is identified during the periodic inspection as identified in BS-7671: and IET Guidance Note 3
Explain the action required by the inspector when the Extent and Limitions agreed may not be achived on site
Explain the difference between defects and non-compliances
Explain why fault finding and remedial work does not form part of the periodic inspection process