Re-take - Useful Information for 2394 :

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Q ) Explain how the inspector confirms that the installation complies with the requirements for prospective fault current protection

A) Confirm measured PFC is no greater than the breaking capacity ( or Icn ) of the protective devices

Comments
An alternative response would be : Protective device ( Icn ) is equal to or more than the measured PFC

GN-3 : P56 . The difference between the two short-circuit rating . refer to .

( Icn ) is the maximum fault current the device can interrupt safety without loss of performance .

for domestic installations the ( PFC ) is unlikely to exceed 6kA , up to which value ( Icn will equal Ics ) refer to .

 

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2395: Section B .

Remember that the answers to the following Q must relate to the scenario contained in the source document

4 a) Describe three actions the inspector can take to ensure that no danger occurs to those persons using the premises during the inspection & test .

A) inform people of the activities , use of barriers to secure work areas , use of warning signs .

Comments
Other answers could include safe isolation , avoidance of tripping hazards , not leaving covers open when unattended and so on , So any three suitable responses will be awarded marks . The responses should relate to avoiding danger to the user of the installation during the inspection & testing process . Working out of hours or when the hall is empty are not acceptable as the Q relates to the ( USERs ) whilst they are in the premises .

The examiner will mark only the first three answers provided as the question specifies three actions .

4 b) State the documents 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 .

Comments
These are the requirements identified in BS-7671: Titles used on the Standard Forms such as generic schedule of test results & Condition Report Inspection Schedule would also be accepted , Schedule of Test , Schedule of items tested etc will not attract marks .

4 c) An inspection is being carried out within the distribution board .
i) State three areas relating to the circuit breakers that are to be inspected .

A) Rating , Type , Short-circuit capacity

Comments
Other answers such as terminations , thermal damage would also be acceptable , The answers must relate to the circuit breakers & be inspection items not functional checks , Any three suitable answers will attract marks .

The examiner will mark the first three answers provided as the question specifies three areas .

4 c) ii) State what is being looked for by the inspector for each item in (i) above .

A) Correct circuit breaker rating , the correct type ( B , C , D ) is installed , the short-circuit rating is higher than the ( Ipƒ )

( Ipƒ ) prospective fault current . by Definitions' R/P.38

Comments
The answers given here must relate to the areas indentified in ( 4 c ) (i) and be in the same sequence to achieve the marks

The examiner will mark only the first three answers provided as the question specifies three areas .

4 c ) iii) State the human sense that will be used during each check in (ii) above .

A) Sight , Sight , Sight .

Comments
in this example all the checks would be carried out using the same sense and so an answer starting all three by sense of sight would be acceptable . if the terminations were used then touch would be appropriate and so no .

The examiner will mark only the first three answers provided as the question specifies three areas .

State the human sense that will be used , its here to stay . 2392 , 2394 , 2395 .

recap : R/P.29 . in the eyes of BS-7671:2011: Inspection .
Examination of an electrical installation using all the senses as appropriate .

 

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Level 3 Certificate in Initial Verification & Certification of Electrical Installation 2394-01 .
Quotes : taken .

C&Gs does not state formal candidate entry requirements .
The qualification is not intended for non-qualified electricians' and / or those who do not have experience in inspecting , testing & certifying electrical installations .

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 : Many candidates were unable to state what was meant by the BS-EN-60898 circuit breaker ratings of ( Icn & Ics )

Testing
A number of candidates incorrectly stated that the earthing and bonding conductors are disconnected before carrying out a test of Prospective Fault Current (PFC).

A number of candidates failed to identify that the test for PFC was undertaken at the supply side of the main isolator.

When describing live tests many candidates did not state the need to confirm that the test leads complied with GS-38

Level 3 Certificate in the Periodic Inspection Testing & Certification of Electrical Installation 2395-01 .
Quotes : taken .

This qualification is intended for Experience people working in the electrical industry . Etc

2395 is one of the hardest Exams to undertake . it's not a walk-in the Park .

 

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2395 :

2 c ) The lighting comprises a number of discharge luminaires .
State the alternative methods of preparing this circuit for the insulation résistance test .

A) Disconnect all luminaires or link live conductors and then test live conductors to Earth .

C ;
An alternative answer for one of these is to switch off at the local switch .

tip ; When testing insulation résistance the measurements must be taken to Earth & disconnecting & testing to a CPC will result in marks being lost .

3 a ) (i) Explain the cause of voltage drop within an installation .

A) Volt drop is a product of the conductor résistance and the load current .

C ;
The question refers to the volt 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 .

A) Measurement & Calculation .

C ;
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 the tables in Appendix 4 of BS-7671: which are generic design details for the calculation of appropriate cable sizes .

3 b ) (i) A radial circuit has a load current ( Ib ) of 28A at 230V a.c. and has a combined live conductor résistance of ( 0.16Ω ) at ( 20ºC ) Determine the voltage drop for this circuit , Show all calculations ◄

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

C ;
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 volt 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:

A) Maximum volt drop = 230V x 5% = 11.5V ... As 5.376V is equal to or less than 11.5V so complies

C ;
Alternative calculations such as : maximum volt drop = 5% drop = 5.376 / 230 x 100 = 2.3% which is less than 5%
may be used & will attract the same marks .

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 , marled accordingly , candidate 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 .

 

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Q/As 2394:
in order to undertake the inspection & testing of an electrical installation a person must be a ;
Competent person
Principle person
Duty person
Registered person

.. take your best shot . R/P/389 under the heading of (i) (ii) (iii) . Competent persons will , as appropriate to their functions

Regulation 16 of the Electricity at Work Regulations requires persons to be competent to prevent danger .
As such danger can occur when carrying out an inspection & test on an electrical installation , the inspector is required to be competent , this is further reinforced in GN-3 as certification & reports are required to be signed by a competent person .

 

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Q/As
The term " Dutyholder " used in the Electricity at Work Regulations refers to the person :
making the final payment on completion of the work
responsible for the electrical installation
reviewing the documents
ordering the work

Electricity at Work Regulations identifies anyone taking control of , or responsibility for , an electrical system as a Dutyholder ( Memorandum of Guidance Regulation 3 item 55 ) Dutyholder.s have a duty to ensure the safety of themselves and others .

 

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Q/As 2394:
Which of the following identifies the correct process for safe isolation of a circuit protected by a circuit breaker

Switch off , post notices
Switch off , lock off , post notices
Switch off , confirm isolation , post notices
Switch off , lock off , confirm isolation , post notices

All of the steps listed in option are required to complete isolation and to ensure the circuit is safe to work on .

 

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Q/As 2394:

Work is to be carried out on an installation which includes a Solar ( PV supply system ) Which of the following must be carried out before isolating the ( DNO ) supply to the installation

Isolate the Solar PV supply .
Disconnect the installation loads .
Closes all the switches .
Disconnect the bonding conductors .

Solar PV system's generate even at low light levels and to ensure the safety of the inspector and those persons in the vicinity the system must be isolated .
Solar PV system's are an alternative source of supply . Although many Solar PV system's will shut down automatically following loss of supply . this should never be taken for granted and isolation of the PV system should always be carried out .

 

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Q/As 2394:

A test of earth fault loop impedance is to be carried out in an area which is accessible to the public , Which of the following is not a suitable method of protecting the public from the risk of electric shock . .. PS the word is NOT

Barriers .
Warning signs .
Safe isolation .
Restricting access .

Safe isolation is not appropriate in this instance as the test is a live test and so has to be carried out with the supply connected .

 

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Q/As

Work is to be carried out at the distribution board supplying a multi-storey office building , which of the following must be placed out of service , to ensure the safety of the users , before the safe isolation of the distribution board is carried out .

General lighting circuits.
Air conditioning system .
Lifts to all floors .
Burglar alarms .

The client's agreement to isolate the lift supplies must be obtained and the lift's taken out of service to prevent persons being trapped in the lifts when the supply to the distribution board is isolated .

 

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Q/As 2394 .
Who is most at risk when an Inspector fails to isolate a lighting circuit before removing a luminaire cover to carry out an inspection .

The inspector .
Other operatives .
The general public .
The client .

As the work is being carried out by the inspector and the other persons listed are unlikely to have access to the luminaire the inspector is at most risk when isolation is not carried out prior to dismantling .

 

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Q/As 2394 .

Which publication specifically identifies the need for electrical installations to be safe for use and maintained in that condition .

HSE Guidance GS-38
Electricity at Work Regulations
The Health & Safety at Work ( etc ) Act
Electricity Safety , Quality & Continuity Regulations .

Regulation 4 of the Electricity at Work Regulations requires electrical systems to be installed and maintained so far is reasonably practical to prevent danger .

 

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Q/As 2394 .

Which publication specifically indentifies the requirements for test leads & probes to be used when carrying out tests at 230V a.c.

BS-7671
HSE Guidance GS-38
Electricity at Work Regulations
Provision and Use of Work Equipment Regulations

HSE GS-38 provides guidance on the test equipment used for circuits with rated voltages not exceeding 650V

 

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Q/As 2394 .

Which test is used to confirm the correct connection of a three-phase socket-outlet .

Phase sequence .
Insulation résistance
Earth fault loop impedance .
Operation of residual current devices .

A three - phase socket-outlet should be confirmed as having correct Phase sequence to ensure the correct connection of any equipment plugged into it . The other test listed will confirm the compliance of the circuit .

 

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Q/As 2394 .

Which test is required to confirm the correct operation of a 30mA RCBO installed to provide additional protection .

Phase sequence .
Insulation résistance
Earth fault loop impedance .
Operation of residual current devices .

The operation of the RCD component of the RCBO must be tested to confirm correct operation , as required in GN-3 .