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Sample Questions - C&G 2382 17th Edition
1 o/c1 BS 7671 does not apply to
a equipment of aircraft
b
photovoltaic systems
c marinas
d fairgrounds.
Answer a
See Part 1: Scope, Regulation 110.2.
Installations that are excluded (out of scope) from BS 7671 (110.2):
1.
2.
3.
Systems for the distribution of electricity to the public
Railway traction equipment, rolling stock and signalling equipment
Equipment of motor vehicles, except those to which the requirements of the Regulations concerning caravans or
mobile units are applicable
4. Equipment on board ships covered by BS 8450
5. Equipment of mobile and fixed offshore installations
6. Equipment of aircraft
7. Those aspects of mines and quarries specifically covered by Statutory Regulations
8. Radio interference suppression equipment, except so far as it affects safety of the electrical installation
9. Lightning protection of buildings covered by BS EN 62305
10. Those aspects of lift installations covered by relevant parts of BS 5655 and BS EN 81-1
11. Electrical equipment of machines covered by BS EN 60204
12. Electric fences
13. The DC side of cathodic protection systems complying with the relevant part(s) of listed standards
14. The circuit voltage is greater than 1,000 VAC, or 1,500 VDC
2
a
b
c
d
o/c1 - Which of the following electrical installations is not covered by BS 7671:
photovoltaic systems.
agricultural and horticultural.
low voltage generating sets.
public electricity distribution.
3 o/c1 BS 7671 applies to
a
equipmentpn board ships
b
lightning protection of buildings
c
lift installations
d prefabricated buildings (προκατασκευασμένα κτίρια)
Answer dSee Part 1, Chapter 11, Scope. Option d, prefabricated buildings, is listed in
Regulation 110.1,
4 oc1 BS 7671 requires protection against electric shock to be provided , by basic
and fault protection. One method common to both is
a the use of RCDs
b the use of Class H equipment
c preventing current from passing through any person or livestock
d the use and implementation of equipotential bonding.
Chap 13 131.2.2
Protection Against Shock
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1. Basic Protection - Limit the current flow to a person
 Insulation of Live Parts (416)
 Class II equipment (412)
 Barriers and Enclosures (416.2)
 Non conducting location (418.1) restricted to trained personnel
 Obstacles and placing out of reach (417)
 Electrical Separation (413, 418.3) also (411.6)
Basic Protection where supervised by a skilled or instructed person
 Non-conducting Location (418.1)
 (No earth contact at sockets)
 Earth Free local equipotential bonding (Faradays Cage)
 Obstacles
 Placing out of Reach
 Electrical separation from more than one item of electrical equipment (common neutrals in IT
systems)
2. Fault Protection (Indirect Contact)
 Automatic Disconnection of supply (ADS)
 SELV, PELV, FELV
 The use of RCDs
 Class II equipment
3. Limit the current flow through a person Basic and Fault protection)
 SELV, PELV, FELV, RLV (414,411.8)
 Earth free protective earth bonding zone (418.2)
5 o/c2 Which of the following would be defined as a live part?
a Earthing conductor
b Line conductor
c Exposed-conductive-part
d PEN conductor
Answer b See Part 2: Definitions.
6 o/c 2 - A protective conductor connecting exposed conductive parts of equipment to
the main earth terminal is a:
a equipotential bonding conductor.
b main bonding conductor.
c earthing conductor.
d circuit protective conductor
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7 o/c2 Protection against electric shock under single-fault conditions is defined
as
a
overload protection
b fault protection
c
basic protection
d
undervoltage protection.
Answer b
See Part 2: Definitions.
8 o/c3 The effectiveness of protective measures (προστατευτικά μέτρα)
should be considered with regard to
a
external influences
b safety services
c maintainability (συντηρησιμότητα)
d compatibility.
Answer c See Part 3: Assessment of general characteristics, Regulation 341.1.
9 o/c 3 - When assessing (αξιολογώντας) the frequency and quality of maintenance of
an installation the person responsible for the operation and/or maintenance of the
installation shall be:
a
B
c
d
consulted. (συμβουλευτικός)
informed.
invoiced.
named.
10 Oc3 With reference to the nature of the supply, which one of the following
can be determined by calculation, enquiry (έρευνα) or measurement?
a
The maximum demand of the installation
b
The rating of the circuit protective device
c
The prospective short-circuit current at the origin of the installation
d The csa of the tails
reg 313.1
11 oc3 To ensure continuity of supply to one part of the installation in the event of
failure of another part, one approach is
a
for a separate circuit to be installed for each part
b to use protective equipotential bonding
c
to install larger fuses
d
to install a 100 mA S type RCD.
314.2
12 oc3 When making an assessment (αξιολόγηση) of the frequency and quality of
maintenance, a factor to be considered is that
a
b
power factor is monitored
protective measures for safety remain effective c
starting currents are at a minimum
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d
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unbalanced loads need to be checked more frequently.
13 o/c4 Where the measure (μέτρο) of automatic disconnection of supply is
employed,(χρησιμοποιείται) fault protection may be provided by
a
protective earthing only
b
protective equipotential bonding only
c
protective earthing and protective equipotential bonding
d electrical separation.
Answer d See Part 4: Protection for safety, Regulation 411.1.
Fault Protection (Indirect Contact)
 Automatic Disconnection of supply (ADS)
 SELV, PELV, FELV
 The use of RCDs
 Class II equipment
SELV - Safety (Separated) Extra-Low-Voltage
Extra-Low-Voltage system (i.e. normally not exceeding 50 V a.c. or 120 V ripple-free d.c.) which is
electrically separated from earth and from other systems in such a way that a single fault cannot give
rise to an electric shock.
PELV - Protective extra low-voltageAn extra low-voltage system which is not electrically separated
from earth but which otherwise satisfies all the requirements for SELV.
14 o/c 4 Which of these is not is not suitable for a SELV
system
a Engine driven generator
b Auto step up transformer
c BS 3535 safety ransformer
d Lead - acid battery
15 10 o/c 4 - Which of the following items does not offer ‘basic’
protection:
a a circuit protective conductor.
b a socket outlet.
c a lampholder.
d equipotential bonding conductors.
16 o/c 4 - A 230V circuit is protected by a 20A Type B circuit-breaker to BS
EN 60898. The minimum value of fault current to ensure compliance with
maximum disconnection times:
a 80A.
b 100A.
c 125A.
d 150A.
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17 o/c 4 Max Zs for a TT system with a 300mA RCD
1667 ohms
500 ohms
167 ohms
100 ohms
18 o/c 4 When protecting against burns (εγκαύματα) a metallic part intended to be
touched but not hand held shall be limited to a maximum temperature of:
a 70 ºC.
b 75 ºC.
c 80 ºC.
d 85 ºC.
Table 3.1 Allowable surface temperatures for accessible parts
(taken from [Table 42A] of BS 7671: 1992)
Max. Temp (°C)
Part
Surface material
Hand held
Metallic
55
Non-metallic
65
Metallic
70
Non-metallic
80
Metallic
80
Non-metallic
90
May be touched but not held
Need not be touched in normal use
19 o/c 4- Correct co-ordination (ορθός συντονισμός) between circuit
conductors and an overcurrent protection device is achieved when:
a In exceeds the lowest current carrying capacity Iz.
b In is less than the design current Ib.
c Ib is less than Iz.
d Iz is lower than or equal to Ib
Iz
is the current carrying capacity of the cable in the situation where it is installed
Ib
is the design current, the actual current to be carried by the cable
In
is the rating of the protecting fuse or circuit breaker
I2
is the operating current for the fuse or circuit breaker (the current at which the fuse blows or the
circuit breaker opens)
Ca
is the correction factor for ambient temperature
Cg
is the correction factor for grouping
Ci
is the correction factor for thermal insulation.

Ib < = In < = Iz and I2 < = 1.45 x Iz
20 o/c4 - Correct co-ordination between conductors and the circuit overcurrent
protective device is achieved when:
On_Disc
a
b
c
d
16
In is less than Ib.
In does not exceed Iz.
Ib > 1.45 IZ.
Ib exceeds IZ.
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21 o/c 4 Except for equipment for which an appropriate product standard specifies
requirements, a luminaire φωτιστικό shall be kept at an adequate επαρκής distance
from combustible εύφλεκτα materials. Unless otherwise recommended by the
manufacturer, a small spotlight or a projector rated at over 100 W and up to 300 W
shall be installed at the following minimum distances from combustible materials.
a 0.3M
b 0.5M.
c 0.8M. (422.3.1)
d 1.1M
The above figure shows minimum distance from a lighted object (m). Regulations 422.3.1 and 422.4.2 give the following minimum distances
at which spotlights and projectors shall be installed from combustible εύφλεκτα materials:
(1) rating up to 100 W - 0.5 m
(2) rating over 100 W up to 300 W - 0.8 m
(3) rating over 300Wup to 500W- 1.0m.
22 o/c4 A 6A BS EN 61009 RCBO with a maximum value of earth fault loop
impedance of 1.92
is type
a
A
b
B
c
C
d
D.
Answer d
See Part 4: Protection for safety, Regulation 411.4.7, Table 41.3.
MCB Type
B
C
D
Minimum trip value
3 In
5 In
10 In
Maximum trip value
5 In
10 In
20 In
Example: MCB 6A. for type D maximum Zs = 230/(20*6) = 1,92Ω
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23 Oc4 An undervoltage device has operated and restoring the supply may cause
danger. The reclosure of this device should be
a
automatic when under the supervision of a competent person
b
manually operated
c
possible only with the use of a key or tool
d automatic with time delay.
Answer bSee Part 4: Protection for safety, Regulation 445.1.5.
445.1.5 Where the reclosure of a protective device is likely to cause danger, the reclosure
shall not be automatic.
24 o/c4 A SELV source can be derived from which one of the following?
a
Double-wound transformer
b Autotransformer
c
Safety isolating transformer
d Step-up transformer
414.3
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25 o/c4 In locations with increased risks of fire, motors which are automatically
or remotely controlled, or which are nolt continuously supervised, shall be
protected against excessive temperature by
a
a protective device that is automatically reset b
a protective device with manual reset
c
electronic monitoring equipment that resets
d
electronic monitoring equipment that restarts the motor.
422.3.7
26 oc4 A BS 88-6 32 A fuse with U0 of 230 V has a maximum tabulated Zs for 5
seconds disconnection of
a 0.36 ohm
b 1.04ohm
c 1.44ohm
d 1.84Qohm
table 41.4
27 o/c5 - When cables are placed directly in the ground they should be buried at a
depth:
a sufficient to avoid damage. b
of not less than 1.0 m.
c sufficient to allow easy access. d
of not less than 1.5m.
γύρω στ
28 o/c 5 Which of the following may be used to provide emergency switching for a
motor:
a a plug and socket.
b a luminaire connection device.
c a device which latches in the OFF position.
d d a key switch.
29 o/c 5 - BS 5839 deals with the system design, installation and servicing of: a
low power supply sources.
b emergency escape lighting. c
fire alarms.
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d generator supply sources.
30 o/c 5 An industrial board supplies 4
x TP motors
2 x TP&N motors
4 x single phase ring circuits
2 x single phase lighting circuits
how many live conductors are there.
(40)
31 o/c5 A cable concealed in a wall outside the prescribed zones at a depth of
less than 50 mm must
a
not be installed
b
be enclosed in unearthed conduit
c be enclosed in earthed metallic conduit
d be protected by a 500 mARCD.
Answer c See Part5: Selection and erection of equipment, Regulation 522.6.6.
32 o/c5 Which of the following is the symbol for a "class P" thermally protected
independent lamp ballast permitted for mounting on a flammable surface?
Answer c
See Part 5: Selection and erection of equipment, Regulation 559.7 and Table 55.2.
33 o/c5- A permanent warning notice must be fixed at or near the point of connection
of every earthing conductor to an earth electrode bearing the words:
a Safety Electrical Connection – Do Not Remove.
b Earth Bonding – Danger.
c Safety Electrical Earth – Do Not Remove.
d Electrical Connection – Danger.
34 o/c5 - Cables and equipment in circuits feeding motors shall be suitable for a
current of at least:
a the full-load current rating of the motor.
B half the full-load current rating of the motor.
C twice the full-load current rating of the motor.
d four times the full-load current rating of the motor.
35 o/c5 - Accessible street furniture enclosures containing live parts shall only be
opened using a:
On_Disc
a
b
c
d
20
key or tool.
ladder.
insulated screwdriver.
harness.
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36 o/c5 An RCD that is installed for protection against the risk of fire where
combustible materials are stored shall be
a
installed at the farthest point of the circuit
b
installed at the origin of the circuit
c
arranged to switch line conductors
d rated at 500mA.
Answer b
See PartS: Selection and erection of equipment, Regulation 532.1.
Where a 30 mA RCD is installed upstream of a residual current monitor (RCM),
the rating of the RCM shall not exceed
Answer b
See Part 5: Selection and erection of equipment, Regulation 559.4 and Table 55.2.
37 o/c5 A firefighter's switch shall be provided in the low voltage circuit
supplying exterior electrical installations and interior discharge lighting operating
at
a
a voltage exceeding low voltage
b low voltage
c voltage band II d
medium
voltage.
537.6.1
38 Where a 3-core cable, with cores coloured brown, black and grey, •:
as a switch wire for two-way or intermediate control, the
terminations of the conductors shall be identified using
a
red, blue and yellow tape
b
black tape only on each core
c brown tape on the black and grey cores
d self-colour tape only.
514.4.4
is used
39 o/c5 A radial final circuit feeding socket-outlets supplying several items of
data processing equipment has a total protective conductor current in normal
service of 18 mA. This circuit must have a high integrity protective conductor
a of cross-sectional area less than 1 mm2
b connected as a ring
c controlled by an isolator
d enclosed in insulated conduit only.
543.7.2.1
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40 oc5 When selecting equipment for an installation, the person who makes the
final decision over its safety would be the
a representative of a regional supply company
b representative of a national inspection body
c designer or other person responsible ΜΕΛΕΤΗΤΗΣ
d inspector and tester.
Sec511 511 .2
41 oc 5 The minimum information contained on a periodjc inspection and testing
notice would be the
a
date of inspection and inspector's name
b date of next inspection and client's name
c date of last inspection and date of next inspection
d company's address and date of next inspection.
514.12.1
42 o/c6 612.3.2 - The minimum insulation resistance between conductors for an
extra-low voltage circuit is:
a 0.25 MΩ.
b 0.5 MΩ.
c 1.0 MΩ.
d 2.0 MΩ
43 o/c 6 - With regard to determining the frequency of periodic inspection and
testing of an installation, which of the following does not need to be considered:
a results of previous reports.
b the installation use.
c the frequency of maintenance.
d the quality of the test instruments.
44 o/c 6 - Which of the following statements is incorrect:
a periodic inspection is carried out to check for heat arising from an installation
defect.
b a schedule of inspections and test results must accompany a periodic inspection
report.
c periodic inspection and testing must be carried out by a fully qualified electrician.
d where possible, results from previous inspection and testing must be taken into.
45 o/c6 - BS 7671 recommends that continuity testers shall be capable of having a
no-load voltage between:
a 4V and 24V d.c. or a.c.
b 4V and 24V d.c.
c 24V and 250V a.c.
d 24V and 250V d.c. or a.c.
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Section 6
46 13 Which of the following is the designated symbol for a high pressure sodium
lamp with an internal starting device?
47 oc6 When carrying out an inspection of a new installation, it is not necessary
to verify the
a total earth fault loop impedance for each circuit
b connection of conductors
c methods of protection against electric shock
d presence of diagrams, instructions and similar information.
611.3
48 o/c7 - In a location containing a bath or shower supplementary bonding may be
omitted, παραλειφθεί amongst other conditions, where: :
a all final circuits have additional RCD protection.
b main equipotential bonding is not required.
c automatic disconnection of most final αν ήταν για all..! circuits of the
location comply with Regulation 411.3.2.
d luminaires are situated outside the Zones.
Supplementary equipotential bonding
The 17th Edition introduced a significant change for supplementary equipotential bonding. Regulation 701.415.2
states that, where the location containing a bath or shower is in a building with a protective equipotential
bonding system in accordance with Regulation 411.3.1.2, supplementary equipotential bonding may be omitted
where all of the following conditions are met:
(i) all final circuits of the location comply with the requirements for automatic disconnection in accordance with
411.3.2;
(ii) all final circuits of the location have additional protection by means of an RCD in accordance with
701.411.3.3; and
(iii) all extraneous-conductive-parts of the location are effectively connected to the protective equipotential
bonding in accordance with 411.3.1.2.
This means that the designer needs to make an assessment that all extraneous-conductive-parts of the
location are effectively connected to the protective equipotential bonding, in accordance with 411.3.1.2.
49 o/c7 For an agricultural αγροτική location, in order to provide automatic
disconnection of supply in circuits other than socket-outlet circuits, a
disconnection device shall be installed having a maximum rated residual operating
current of
a
30mA
b 100mA
c 300mA
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d 500mA.
Answer cSee Part 7: Special installations or locations, Regulation 705.411.1.
5.5.1Protective measure: Automatic disconnection of supply
705.411.1 RCDs must be provided for automatic disconnection of supply to circuits as follows (see Figure 5.1):
705.411.1
In circuits, whatever the type of earthing system, the following disconnection devices shall be
provided:
415.1.1 (i) in final circuits supplying socket-outlets with rated current not exceeding 32 A, an RCD having the
characteristics specified in Regulation 415.1.1;
(ii) in final circuits supplying socket-outlets with rated current more than 32 A, an RCD with a rated
residual operating current not exceeding 100 mA; and
(iii) in all other circuits, RCDs with a rated residual operating current not exceeding 300 mA.
50 o/c 7 - On caravan τροχόσπιτα sites, overhead conductors in areas
subject to vehicle movement shall be placed at a minimum height above
ground of:
a 2.5 m.
b 3.5 m.
c 6.0m.
d 8.0m.
7.5.2Overhead and underground distribution
708.521.1
708.410.3.5
BS 7671 states a preference for distribution by underground cables. Underground cables should be buried at a depth of at
least 0.6 m and should be routed outside any caravan pitch or away from areas where tent poles or ground anchors could be used, unless
additional mechanical protection is provided. Overhead distribution systems are allowed provided all conductors are insulated and so
erected as to be unlikely to be damaged by vehicle movement. They are required to be not less than 6 m above ground level in areas
subject to vehicle movement and 3.5 m in all other areas. Suitable warning notices should be displayed at the entrance to the site and on
supports for the overhead line and, where appropriate, attention drawn to the danger of masts of yachts or dinghies contacting the
overhead line.
51
a
b
c
d
o/c 7 - A PV convertor shall have a switch-disconnector provided on:
the a.c. side.
the d.c. side.
the a.c. and d.c. sides.
neither the a.c. nor the d.c. sides.
52 o/c 7 - Which of the following systems shall not be used to supply equipment used
in repair and alteration work on construction sites:
a TN-S.
b TN-C-S .
c TT.
d separate earth and neutral supplies.
704.411.3.1 A PME earthing facility shall not be used for the means of earthing for an installation falling within the scope of
this section unless all extraneous-conductive-parts are reliably connected to the main earthing terminal in accordance with
Regulation 411.3.1.2.
NOTE :If the PME earthing facility is considered for use, see also BS 7375
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53 o/c 7 - In a sauna which one of the zones has no special requirements concerning
the heat resistance of the equipment:
a 1.
b 2.
c 3.
d 4.
Three zones are defined as shown in Figure 703:
(i) In zone 1: only the sauna heater and equipment belonging to the sauna heater shall be installed
(ii) In zone 2: there is no special requirement concerning heat-resistance of equipment
(iii) In zone 3: the equipment shall withstand a minimum temperature of 125 °C and the insulation and sheaths of
cables shall withstand a minimum temperature of 170 °C (see also Regulation 703.52for wiring).
54 o/c 7 - Electrical equipment installed outside in caravan parks shall be protected
against mechanical stresses to a minimum of:
a AG3.
b AD4.
c AE2.
d AD3.
708.512.2 External influences
Electrical equipment installed outside in caravan parks shall comply at least with the following external influences:
(i) Presence of water: AD4(splashes), IPX4in accordance with BS EN 60529
(ii) Presence of foreign solid bodies: AE2(small objects), IP3Xin accordance with BS EN 60529
(iii) Mechanical stress: AG3(high severity), IK08 in accordance with BS EN 62262.
55 o/c7 The maximum length of a flexible cord or cable for a caravan connection
is
a
1.8m
b
6m
c
10m
d
25m.
Answer d
See Part 7: Special installations or locations, Section 708, Fig 708, or Regulation
721.55.2.6.
The means of connection between the caravan pitch socket-outlet and the leisure accommodation vehicle should be an
assembly of the following:
- a plug complying with BS EN 60309-2;
- a flexible cable type H05RN-F ( BS EN 50525-2-21) or equivalent, with a protective conductor and having the
following characteristics:
- continuous length 25 m (±2 m)
56 oc7 In a swimming pool or other basin, the metallic covering or sheath of a wiring
system in zones 0,1 or 2 shall
a not be used
b not be earthed
c be connected to the supplementary bonding
d have reinforced insulation.
702.52 702.522.21
702.415.2
702.52
Supplementary equipotential bonding is required between all extraneous-conductive-parts and the protective conductors of
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all exposed-conductive-parts in zones 0, 1 and 2, irrespective of whether they are simultaneously accessible, in accordance with
Regulation 415.2. In zones 0, 1 and 2, any metallic sheath or metallic covering of a wiring system (e.g. conduit), either surface-run or
embedded in walls, floors etc. at a depth not exceeding 50 mm, must be connected to the supplementary equipotential bonding.
57 oc7 Electric dodgems shall only be operated at voltages not exceeding
a
120Va.c.or50Vd.c.
b 50Va.c.or120Vd.c.
c
110 V a.c. reduced low voltage
d 1000Va.c.oM500Vd.c.
740.55.9
However, placing out of arm's reach is acceptable for electric dodgems operated at extra low voltage under
special conditions.
SELV - Safety (Separated) Extra-Low-Voltage
Extra-Low-Voltage system (i.e. normally not exceeding 50 V a.c. or 120 V ripple-free d.c.) which is
electrically separated from earth and from other systems in such a way that a single fault cannot give
rise to an electric shock.
58 7 o/c 8 app7 - In the new colouring system the neutral in a three-phase a.c.
system will be:
a brown
b red
c black
d blue
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59 oc8 I2 can be greater than 1.45 lz when the overcurrent device
a
is providing overload protection
-*
b is a circuit-breaker
c
is rated at over 100 A
d
is providing fault current protection only.
App4 sec 3 (434.5.2)
60 20 A final circuit is the wiring between
a supply company's fuse and the energy meter
b main switch and the distribution board
c distribution board and current using equipment
d supply company's fuse and the remotest outlet point
App15
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