Tuesday 12 July 2011

2391 exam preparation




This Section is highlight the areas covered by the 2391 syllabus. Student are expected to
have knowledge of all that is in the syllabus.
Requirements for the Level 3 Level 3 Certificate in the Certification of Electrical
Installations (inspection, testing and certification of electrical installations) (2391-10)
For this qualification, candidates will be required to complete the following assessments:
A written assessment covering outcomes 1-3
A practical assessment
It will be graded pass or fail.
Duration: 2.5 hours
No of questions: 26
This written paper is in two sections. Section A consists of 20 short answer questions
worth 60 marks (1 hour approximately). Section B will consists of 6 structured questions
worth 90 marks (1.5 hours approximately).
Here is the Break down of the examination content.
Section Outcome Unit Title Number of
items
Approximate
percentage %
1 Preparation for
inspection
and testing
3 6
Section A 2 Inspection 2 4
3 Testing 15 30
1 Preparation for
inspection
and testing
Section B 2 Inspection 6 60
3 Testing
Total 26 100

Technical knowledge of the inspection, testing and certification of electrical
installations
The aim of this unit is to enable the candidate to develop the necessary technical
knowledge and understanding about the inspection, testing and certification of electrical
installations.
It is recommended that 15 hours should be allocated for this unit. This may be on a full
time or part time basis.
This unit will be assessed by written examination.
Learning Areas
There are three areas to this unit. These include a knowledge and understanding of:-
Preparation for inspection and testing
Inspection
Testing
Preparation for inspection and testing
The candidate will be able to:
State the need for and the purpose of initial verification and periodic inspection and testing
State the information required to correctly conduct the inspection and testing of an
installation
State the statutory and non-statutory requirements and relevant guidance material that
apply to the activity of inspecting and testing of electrical installations
State the need to comply with statutory and non-statutory requirements, and guidance
material for particular locations and environments in which electrical installations are
installed
State the information to be contained on Certificates and Inspection Reports and how the
information is recorded on all certificates as indicated in BS 7671 (current edition).

Inspection
The candidate will be able to:
State the human senses that may need to be employed during the inspection of an
installation
Refer to and identify the items to be checked during the inspection process for given
systems and locations as detailed in BS 7671 (current edition)
State the particular requirements for a periodic inspection of an electrical installation as
defined in BS 7671 (current edition)
State the need to establish the extent and limitation of a Periodic Inspection Report, with
the client and any relevant third parties, prior to commencing the inspection, and the need
to record these details on the Periodic Inspection Report.
State the requirements of the Electricity at Work Regulations for safe inspection and
testing in terms of those
carrying out the work
using the installation and the building during the inspection and testing.
Testing
For each topic the candidate will be able to:
Instruments
State the need for instruments to be regularly checked and the need for their compliance
with the requirements of BS 7671 (current edition) and HSE Guidance Note GS 38
List the correct instruments, their characteristics and the appropriate scale to carry out
each test and explain the reasons for each choice
State the recommended sequence of tests and the reasons for that sequence
Protective Conductors
State the requirements which need to be considered for protective conductors in terms of
a) earthing conductors
b) main protective bonding conductors
c) supplementary protective bonding conductors
d) circuit protective conductors

Describe the need for, and methods of verifying, the continuity of protective conductors
and the interpretation of results
State the relationship between conductor length, CSA and resistance
State the effect of temperature on a conductor
Ring Circuits
State the effect on measured resistance when cables are connected in parallel
Describe the need for, and methods of, verifying the continuity of ring final circuit
conductors and the interpretation of results
Insulation Resistance
Explain, by example, the effect on insulation resistance and test results of
a) cables connected in parallel
b) variation in cable length
Compare the differences between measurements taken for insulation resistance and
conductor resistance, stating the order of magnitude that would be expected in each case
State the preconditions required for the performance of insulation testing
State the precautions to be taken before testing insulation resistance
Describe methods of testing insulation resistance
State the required test voltages and minimum values of insulation resistance for
installations operating at various voltages
State the particular requirements for insulation resistance testing of circuits incorporating
surge protection devices (SPDs) or sensitive electronic devices, to include disconnection
and the test voltage to be applied where disconnection cannot be achieved.
Electrical separation/SELV
Describe the tests to verify the separation of SELV circuits
State the particular requirements for protection by electrical separation (NOT SELV)

Special Installations and Locations
Describe the requirements for circuits in prescribed special installations and locations, by:
a) identifying the installations and locations to which special requirements apply
b) demonstrating the ability to make reference to the appropriate requirements in each
case
c) identifying the requirements in relation to specific areas and installations from given
information.
IP Code
State the appropriate minimum degree of protection required for given applications as
identified within the IP classification BS EN 60529
Polarity
Describe the need for and methods of testing used to identify correct polarity
Earth Electrodes
Differentiate between the requirements for testing of earth electrodes for RCD protected
TT systems and electrodes for transformers and generators
Earth Fault Loop Impedance
Describe the earth fault loop impedance paths for the following systems
a) TN-S
b) TN-C-S
c) TT
Describe methods of determining earth fault loop impedance in terms of
a) the tests used for measuring actual earth fault loop impedance
b) methods of calculation of earth fault loop impedance from given data and
measurement of conductor impedance
Given maximum tabulated values of earth fault loop impedance, verify that measured
values are acceptable, taking into account conductor operating and ambient temperatures.

Residual Current Devices (RCCBs/RCBOs)
Describe methods of testing the correct operation of RCDs, independent of in-built test
facilities.
State the applications for various RCD ratings
Prospective Fault Current
Describe methods of determining prospective fault current in terms of
a) prospective short circuit current
b) prospective earth fault current
Explain the importance of selecting protective devices appropriate to the prospective fault
current.
Phase Sequence
Describes the requirements for checking phase sequence in terms of
a) the purpose of checking correct phase sequence
b) test methods used to check phase rotation
Voltage Drop
Describe the methods of verifying voltage drop compliance with BS 7671 in terms of
measuring circuit impedance and calculation.

Practical application of the inspection, testing and certification of electrical
installations
The aim of this unit is to enable the candidate to develop the necessary technical practical
skills about the inspection, testing and certification of electrical installations. Demonstrate a
practical application of the testing inspection, testing and certification of electrical
installations
It is recommended that 15 hours should be allocated for this unit.
Practical Activities
The candidate will be able to:
Select the correct instruments or settings and appropriate scales or ranges to carry out
tests
Check and prove instruments and leads for safety and function
Given the information required carry out the inspection and testing of an installation to the
requirements of BS 7671
Complete a Periodic Inspection report, as given in BS7671, including two Schedules of
Test Results
Carry out an inspection of installation components and record deviations and complete a
Schedule of Inspections
The test rig and inspection and testing equipment
To carry out these inspection and testing practical assessments, simulated installations
should be constructed in accordance with the diagrams given in the Assessment Guide for
Centres.
The test rigs should be located in an area of adequate space and light. All connections
must be directly to the accessories, rather than simulated, and allowance should be made
for the replacement of connections as they become worn.
The test equipment provided by the centre must meet the requirements of BS 7671 and
HSE document GS 38.
To ensure that the candidate has to make a selection from the equipment provided, there
should be a greater range of test instruments available than is actually required to carry
out the tests.
The test instruments for Assessment 4 must include a voltage indicator, with the
necessary proving equipment, to test for correct isolation.

To simulate ‘real’ conditions the test rig must be connected to a 400V three-phase and
neutral supply.
Test procedure
The candidate should be given
a. the appropriate results sheet for the assessment
b. a selection of hand tools where required, to carry out the test of the installation
c. a range of test instruments including those required to complete the tests.
Candidate identification and other relevant information should be completed on the
appropriate result sheet prior to the commencement of each test.
The candidate will be expected to record all relevant information and test results for all
circuits on the appropriate results sheet.
The tests and performance assessment
Consideration should be given to the Electricity at Work Regulations throughout the
assessment process, and it should be made clear to the candidate that failure to observe
appropriate safe working practices will result in the assessment being stopped.

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