Re-take - Useful Information for 2394 :

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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 )

 

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2.5mm[SUP]2[/SUP] / 1.5mm[SUP]2[/SUP] twin T&E cable 22m long . if you look at O.S.G. Table 11 you will see that the résistance of a copper 2.5mm[SUP]2[/SUP] conductor has a résistance of 7.41mΩ per metre

Résistance of the Line-conductor will be : 7.41 x 22 / 1000 = 0.163Ω
divide the largest conductor by the smallest to find the ratio of the conductors .. ( how much bigger is the larger conductor ) 2.5 ÷ 1.5 = 1.67

2.5mm[SUP]2 [/SUP]conductor is 1.67 x larger than the 1.5mm[SUP]2 [/SUP] conductor ; therefore , it must have 1.67 x less résistance than 1.5mm[SUP]2 [/SUP] conductor .
if you now multiply the résistance of the line conductor by 1.67 : 0.163 x 1.67 = 0.27Ω this is the résistance of the 1.5mm[SUP]2 [/SUP] conductor

You can check this by looking at O.S.G. Table 11 you can see that the résistance of 1.5mm[SUP]2 [/SUP] copper is 12.10mΩ per metre . Therefore , 22 metres of 1.5mm[SUP]2 [/SUP] copper will be : 22 x 12.10 / 1000 = 0.266Ω

your final check ; if you look in O.S.G. Table 11 , for the résistance of a 2.5mm[SUP]2[/SUP] / 1.5mm[SUP]2[/SUP] twin T&E cable will see that it has a résistance of 19.51mΩ per metre , and that 22 metres of it will have a résistance of : 22 x 19.51 / 1000 = 0.429Ω .

The résistance value of the 2.5mm[SUP]2[/SUP] is 0.163Ω ....... 2.5mm[SUP]2 [/SUP] copper will be 7.41 x 22 / 1000 = 0.163Ω
The résistance value of the 1.5mm[SUP]2[/SUP] is 0.266Ω ....... 1.5mm[SUP]2 [/SUP] copper will be : 22 x 12.10 / 1000 = 0.266Ω

if you add them together ( 0.163Ω + 0.266Ω = 0.429Ω ) Finally ; 0.429 is the résistance of your 2.5mm[SUP]2[/SUP] / 1.5mm[SUP]2[/SUP] measured as one cable .

 

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Common problems : ( IR ) :icon_bs:

• Low-résistance résistance could be found if a building has been unused for a period of time , due to the installation being affected by dampness in the accessories .

• Low-résistance résistance readings will also often be found where a building has been recently-plastered . :35:

 

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Earthing :
All electrical circuits in a installation must have a protective-earth-conductor ( PE ) , commonly referred to as the circuit-protective-conductor

 

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Test 1 , trouble downloading in forum .

Section A .... Please read the Question carefully ←

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

1 a (ii) State two non-statutory publications to which the inspector may refer whilst carrying out an inspection and test of an electrical installation .

A) BS-7671:2008(2011) and IET Guidance Note 3 .
Com ) Because the question has asked for two answers , only the first two answers given by the candidate would be considered . Other Guidance Notes would be acceptable but the most relevant is Guidance Note 3 .

The On-Site Guide is a perfectly acceptable alternative answer .

 

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Test 2 ,

Section A

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

1 b) State the scope of the Minor Electrical Installation Works Certificate ... ( MEIWC )

A) Alteration or addition to an existing circuit .

Com ) A key part of this answer is the reference to ((( an existing circuit ))) An alteration or addition to an existing installation is NOT within the scope of a Minor Electrical Installation Works Certificate

Any description covering the essential points ((( alteration or addition and existing circuit ))) would get the marks .