1
Q
Front
A
Back
2
Q
What does this presentation cover?
A
Certificate in fundamental inspection, testing and initial verification.
3
Q
Which amendment are examinations now set to in this presentation?
A
BS 7671:2018 Amendment 2 (2022).
4
Q
Which main reference book is used throughout this presentation?
A
IET Guidance Note 3 (the brown book).
5
Q
How is the text colour-coded in the presentation?
A
Green = chapters/paragraphs/diagrams/tables in GN3; Red = page numbers in GN3; Blue = examination information and hints.
6
Q
How many questions are in the online multiple-choice exam?
A
30 questions.
7
Q
How long is the online multiple-choice exam?
A
60 minutes.
8
Q
Is the online multiple-choice exam open book or closed book?
A
Open book (GN3).
9
Q
What are the two parts of the practical assessment?
A
1) Inspection and test of a simulated installation. 2) Completion of an Electrical Installation Certificate for the simulated installation.
10
Q
How long is allowed for the practical inspection and test of the simulated installation?
A
120 minutes total.
11
Q
How many exam questions cover safe isolation?
A
3 questions.
12
Q
How many exam questions cover the requirements for initial verification?
A
2 questions.
13
Q
How many exam questions cover completing an initial inspection?
A
3 questions.
14
Q
How many exam questions cover safe testing and commissioning?
A
4 questions.
15
Q
How many exam questions cover testing prior to being energised?
A
7 questions.
16
Q
How many exam questions cover testing?
A
7 questions.
17
Q
How many exam questions cover completion of electrical installation certificates and associated documentation?
A
4 questions.
18
Q
Which legislation is listed under general requirements as statutory legislation?
A
Health and Safety at Work Act; Management of Health and Safety at Work Regulations; Electricity at Work Regulations; Provision and Use of Work Equipment Regulations; Construction (Design and Management) Regulations; Building Regulations.
19
Q
Which publications are listed as non-statutory regulations and publications?
A
Memorandum of Guidance on the Electricity at Work Regulations; BS 7671; IET Guidance Note 3; GS 38 and other guidance from HSE; British or European Standards.
20
Q
What three key safety considerations are listed in GN3 section 1.1?
A
1) Knowledge of the installation and the test equipment. 2) Suitable test equipment. 3) Condition of test equipment.
21
Q
Which standards are given for suitable test equipment?
A
BS 61010 and BS 5458.
22
Q
Which HSE guidance is referenced for the condition of test equipment?
A
GS 38.
23
Q
What testing situations need special safety consideration?
A
Test voltages over 50 V (such as insulation resistance testing) and live testing (such as loop and RCD testing).
24
Q
What is required competence based on?
A
Sound knowledge and experience, inspection and testing skills, qualifications/professional body membership, understanding of responsibilities, and knowing what action to take on discovering danger.
25
What is the purpose of initial verification?
To verify that electrical equipment is of the correct type and to the relevant standard or equivalent, has been correctly selected and erected, and is not damaged or defective.
26
Who may sign an Electrical Installation Certificate in a multiple-signature arrangement?
Separate signatures may be provided for design, construction, and inspection & testing.
27
What documents accompany a multiple-signature Electrical Installation Certificate?
A Schedule of Inspections and a Schedule of Test Results.
28
To whom is the Electrical Installation Certificate issued?
The person ordering the work.
29
When is a Minor Electrical Installation Works Certificate used?
Where the work does not include the provision of a new circuit, such as extensions to existing circuits or replacement of accessories.
30
Is a Minor Electrical Installation Works Certificate a stand-alone certificate?
Yes. It includes the test results and one is issued for each item of work.
31
To whom is a Minor Electrical Installation Works Certificate issued?
The person ordering the work.
32
What information is required when assessing the general characteristics of an installation?
Maximum demand; number and type of live conductors; earthing arrangement; nominal voltage; nature of current and supply frequency; prospective short-circuit current at origin; external earth fault loop impedance (Ze); type and rating of overcurrent protective device at origin.
33
What additional information may be required in diagrams, charts and tables?
Type and composition of circuits; method used for shock protection; location of devices for isolation and switching; items vulnerable to test.
34
What is the purpose of the initial inspection?
To confirm that the requirements of BS 7671 have been met.
35
When must the initial inspection be carried out?
Before energising new installations.
36
What two conditions must new installations satisfy before energising?
They must be correctly selected and erected, and not damaged so as to impair safety.
37
What should happen during construction regarding inspection and testing?
Appropriate inspection and testing should be conducted and recorded during construction, and the results form part of the Electrical Installation Certificate.
38
What documentation should be provided to the inspector before completion?
The recorded inspection and test results that form part of the Electrical Installation Certificate.
39
What does BS 7671 provide as a minimum for initial inspection?
A list of items that must be inspected as a minimum.
40
Where is the inspection schedule contained?
Within the Electrical Installation Certificate.
41
Whose responsibility is it to ensure the items covered by each inspection heading are met?
The inspector's responsibility.
42
What should be done with test results?
They should be compared with the relevant criteria.
43
What is the correct sequence of tests listed in GN3?
Continuity; insulation resistance; polarity; earth fault loop impedance (and PFC); RCD (and functional tests).
44
Which tests are classed as dead tests?
Continuity of protective conductors including main and supplementary bonding; continuity of ring final circuit conductors; insulation resistance; site-applied insulation; protection by separation of circuits; protection by barriers and enclosures (provided during erection); insulation of non-conducting floors and walls; polarity.
45
Which tests are classed as live tests?
Earth electrode resistance; earth fault loop impedance (Ze and Zs); prospective fault current; RCD testing (additional protection); phase sequence; functional tests including RCDs.
46
Define basic protection.
Protection against electric shock under normal conditions.
47
Define fault protection.
Protection against electric shock under fault conditions.
48
What is an exposed-conductive-part?
A conductive part of electrical equipment that can be touched and is not normally live, but can become live under fault conditions.
49
What is an extraneous-conductive-part?
A conductive part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation.
50
What is an earthing conductor?
A protective conductor connecting the main earthing terminal to an earth electrode or other means of earthing.
51
What is a main protective bonding conductor?
A protective conductor used for main equipotential bonding.
52
What is a supplementary protective bonding conductor?
A protective conductor used for supplementary equipotential bonding.
53
What is a circuit protective conductor (CPC)?
A protective conductor connecting exposed-conductive-parts of equipment to the main earthing terminal.
54
What is the safe isolation sequence given in the presentation?
Select a voltage indicating device; prove it works; test the circuit(s) intended to be isolated; if live, isolate and re-test; lock off and remove fuses as necessary; retain the key; post warning signs; re-prove the voltage indicator.
55
Which instrument is used to test continuity of protective conductors?
A low resistance ohmmeter.
56
How is continuity of protective conductors performed?
Between the ends of the conductors.
57
What should a continuity reading include if the test leads are not nulled?
The resistance of the conductor plus the resistance of the test leads.
58
What does a bonding continuity reading represent when the test leads are nulled?
The resistance of the bonding conductor only.
59
How are circuit protective conductors tested according to the presentation?
Using a low resistance ohmmeter by either Method 2 (long lead) or Method 1 (R1 + R2).
60
In circuit protective conductor Method 2, what does the reading represent?
R2, the resistance of the circuit protective conductor.
61
In circuit protective conductor Method 2, what must be done to eliminate parallel paths?
Disconnect as necessary to eliminate parallel paths.
62
In circuit protective conductor Method 1, what does the reading represent?
R1 + R2, where R1 is the resistance of the line conductor and R2 is the resistance of the circuit protective conductor.
63
What is used in circuit protective conductor Method 1 at the distribution board?
A temporary link between line and CPC.
64
How can the Method 1 setup also be used for a polarity check at a socket?
By operating the switch: with the switch closed there is continuity; with the switch open the circuit reads open circuit, confirming the switch is in the line conductor.
65
What is the purpose of the continuity test of ring final circuit conductors?
To confirm continuity of the ring, detect faults in the ring circuit, and also confirm polarity.
66
What is the result obtained from the special 3-step ring final circuit test?
R1 + R2.
67
What is step 1 of the ring final circuit continuity test?
Identify opposite legs of the ring and measure line-line (r1), neutral-neutral (rn), and CPC-CPC (r2).
68
Which ring final circuit readings are recorded in step 1?
r1, rn and r2 end-to-end readings.
69
For a 2.5 mm² / 1.5 mm² twin and earth ring, how does r2 compare with r1?
The CPC end-to-end value r2 will be approximately 1.6 times higher than the line end-to-end value r1.
70
What is step 2 of the ring final circuit continuity test?
Cross-connect line leg 1 to neutral leg 2 and line leg 2 to neutral leg 1, then measure between line and neutral at the sockets.
71
What should the line-neutral readings at the sockets be during ring test step 2?
Substantially the same at each socket, typically within 0.05 Ω.
72
How is the expected value for line-neutral cross-connect readings calculated?
(r1 + rn) / 4.
73
Is the expected line-neutral cross-connect value recorded?
No, it is used as an expected check value and is not recorded.
74
Where will the line-neutral cross-connect reading usually be higher?
At spurs.
75
What is step 3 of the ring final circuit continuity test?
Cross-connect line leg 1 to CPC leg 2 and line leg 2 to CPC leg 1, then measure between line and CPC at the sockets.
76
What should the line-CPC readings at the sockets be during ring test step 3?
Substantially the same at each socket, typically within 0.05 Ω.
77
How is R1 + R2 for a ring final circuit calculated?
(r1 + r2) / 4.
78
Which measured value is recorded as R1 + R2 for a ring final circuit?
The highest value measured at the sockets during the line-CPC cross-connect check, probably at a spur.
79
At which stage would an open circuit in the line, neutral or CPC ring be identified?
Step 1.
80
What must be done if an open circuit is identified during ring testing?
It must be rectified before commencing steps 2 and 3.
81
What is the important limitation during a periodic inspection regarding ring faults?
You have no remit for fault finding or rectification; you are only reporting on the condition of the existing installation.
82
At which ring test steps would a polarity problem normally be identified?
Steps 2 or 3, but especially step 3 in the example given.
83
What happens in the example where line and neutral are reversed at one socket?
Step 2 may not show a problem, but step 3 (line-CPC cross-connect) would show an open circuit at that socket.
84
What happens if the ring legs are cross-connected incorrectly during testing?
The readings at the sockets start low, rise gradually to the midpoint of the ring, then fall again.
85
How is incorrect cross-connection of ring legs corrected?
Go back and swap the legs around correctly.
86
What is the objective of insulation resistance testing?
To ensure the integrity of insulation.
87
Which instrument is used for insulation resistance testing?
An insulation resistance tester.
88
What minimum insulation resistance is required for SELV and PELV circuits?
0.5 MΩ when tested at 250 V DC.
89
What minimum insulation resistance is required for circuits up to and including 500 V?
1.0 MΩ when tested at 500 V DC.
90
What minimum insulation resistance is required for circuits above 500 V?
1.0 MΩ when tested at 1000 V DC.
91
What does the presentation say about circuits less than 2 MΩ?
They will require further investigation.
92
What precautions should be taken before carrying out insulation resistance tests?
Remove all current-using equipment, remove or isolate all electronic devices such as dimmers, and remove or isolate other equipment that may give false readings such as neon indicators.
93
Between which conductors should insulation resistance tests be made?
1) Between live conductors. 2) Between live conductors and earth.
94
How should switches and protective devices be set for insulation resistance testing?
Switches closed and protective devices in/closed where applicable.
95
What should be done after operating two-way switches during insulation resistance testing?
Retest after operating the two-way switches.
96
When should the single-phase live-conductor-to-live-conductor insulation resistance test be carried out?
Before equipment is connected.
97
At what test voltage may a live-conductors-to-earth insulation resistance test be carried out after equipment has been connected?
250 V DC.
98
What is acceptable where sensitive devices cannot be isolated during insulation resistance testing?
Link line and neutral together and test between the linked line/neutral and CPC.
99
If all devices are isolated, how should insulation resistance to earth be checked?
Test line to CPC and neutral to CPC separately.
100
What is acceptable for devices such as dimmers when carrying out R1 + R2 checks?
They may be linked out for the R1 + R2 checks and then reconnected after the insulation resistance tests.
101
In a full installation insulation resistance test, how will the overall measured value compare with individual circuit values?
It will always be lower than the lowest insulation resistance value of any individual circuit.
102
What is the purpose of a dead polarity test?
To prove that single-pole protective devices break the phase conductor only, that single-pole switches break the phase conductor, and that polarity at sockets and other accessories is correct.
103
Which instrument is used for live polarity testing?
A GS38-compliant voltage indicating device.
104
Between which points is live polarity testing applied in the presentation?
Between incoming line and earth.
105
Which earth electrode resistance test method is Method E1?
Using an earth electrode resistance tester (the 3-point method).
106
What must be disconnected before an E1 earth electrode resistance test?
The main earthing conductor at the MET or the electrode.
107
When is Method E1 usually performed?
Where the supply has yet to be installed.
108
Why is Method E1 not always practical?
It may require up to 30 m of exposed ground.
109
In the E1 earth electrode test arrangement, how far away should the current spike usually be?
Distance A greater than 10 times the electrode length, for example 30 m.
110
In the E1 earth electrode test arrangement, where is the first potential spike position usually placed?
At half the distance to the current spike, e.g. 15 m when A is 30 m.
111
Which earth electrode resistance test method is Method E2?
Using a stakeless earth electrode tester.
112
What type of installation is Method E2 suitable for?
Multi-electrode installations only.
113
How does the accuracy of Method E2 compare with E1 and E3?
It may not be as accurate as methods E1 and E3.
114
Which earth electrode resistance test method is Method E3?
Using an earth fault loop impedance tester.
115
What must be done before carrying out an E3 earth electrode resistance test?
Disconnect the main earth at the MET or electrode, and isolate the supply from the installation during the test.
116
What is Ze?
External earth fault loop impedance.
117
Which instrument is used to measure Ze?
An earth fault loop impedance tester.
118
What must be disconnected before performing a Ze test?
The main earthing conductor at the MET.
119
How must the supply be set during a Ze test?
It must be isolated at the main switch during the test.
120
What is the purpose of the Ze test?
To establish the suitability of the supplied earth.
121
What must be done immediately after a Ze test?
Reconnect the earthing conductor.
122
What live tests are listed together near the end of the presentation?
Prospective fault current, earth fault loop impedance (Zs), RCD test, and functional tests.
123
How may prospective fault current (PFC) be obtained?
By measurement, calculation or enquiry.
124
Which two readings are taken when determining prospective fault current?
Prospective short-circuit current (PSCC) and prospective earth fault current (PEFC).
125
Which prospective fault current value is recorded as Ipf?
The larger of PSCC or PEFC measured at the origin of the supply.
126
Which instrument is used for a prospective fault current test?
A prospective fault current test meter.
127
In what unit is PFC measured?
kA.
128
Where are PFC tests performed?
At relevant points in the installation where protective devices and switchgear are installed.
129
What requirement must protective equipment satisfy regarding PFC?
It must be able to disconnect that prospective fault current.
130
What formula is given for PFC at the origin?
PFC = Uoc / Ze.
131
In the example of a single-phase TN-C-S system with Ze = 0.03 Ω, what is the PFC?
230 / 0.03 = 7666 A.
132
What does the calculated PFC tell you about devices?
They must be capable of disconnecting that current.
133
What is the formula for Zs?
Zs = Ze + (R1 + R2).
134
Where are maximum Zs values found in BS 7671 according to the presentation?
Tables 41.2, 41.3 and 41.4.
135
What does the 0.8 or 80% rule for Zs mean?
The measured reading should be less than or equal to the maximum Zs multiplied by 0.8.
136
Where is a Zs test performed?
At the extreme end of the circuit.
137
Which instrument is used for a Zs test?
An earth fault loop impedance tester.
138
What problem can occur when carrying out a loop test on an RCD-protected circuit?
The RCD may trip.
139
How can nuisance tripping during loop testing be reduced?
Use the meter's no-trip loop function.
140
When an RCD trips during testing, what should be done before recording the result?
Repeat the test at 180° and record the slowest time.
141
What maximum expected operating time is given for an RCD at x1 rated residual current?
300 ms.
142
What maximum operating time is shown at x1 for 30 mA, 100 mA, 300 mA and 500 mA RCDs?
300 ms for all of them.
143
What should Zs test results be compared with?
The maximum permissible values in BS 7671.
144
What must PFC results be checked against?
Whether the protective devices can disconnect that value.
145
What is used to test protection by barrier or enclosure provided during erection?
A BS test finger, 12 mm diameter by 80 mm long.
146
What IP ratings are shown on the slide for protection by barrier or enclosure provided during erection?
IP4X and IP2X.
147
Which forms does the candidate have to complete in the second part of the practical assessment?
Electrical Installation Certificate, Schedule of Circuit Details, and Schedule of Test Results.
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