The fundamental principles stated in BS 7671 for protection against overvoltage are given in Chapter

1.   ?    13
2.   ?    40
3.   ?    47
4.   ?    51.

Which one of the following is listed under exclusions from the scope of BS 7671?

1.   ?    Saunas.
2.   ?    Swimming pools.
3.   ?    Highway power supplies.
4.   ?    Lightning protection

Which one of the following sets of regulations is non-statutory?

1.   ?    Electricity Safety, Quality and Continuity Regulations
2.   ?    Electricity at Work Regulations.
3.   ?    Building Standards Regulations.
4.   ?    BS 7671 Requirements for Electrical Installations.

Protection against direct contact can be achieved by

1.   ?    limiting the current which can pass through the body
2.   ?    ensuring all extraneous parts are at equal potential
3.   ?    automatic disconnection of the supply during earth fault conditions
4.   ?    separation of the supply and load by means of isolating transformer.

Low voltage as defined in BS 7671 has a value not exceeding

1.   ?    250 V a.c.
2.   ?    650 V a.c.
3.   ?    1000 V a.c.
4.   ?    1500 V a.c.

The part of a fuse which is designed to melt when the fuse operates is defined as the fuse

1.   ?    wire
2.   ?    element
3.   ?    link
4.   ?    carrier

An external influence categorised as AG1 applies to a

1.   ?    quarry
2.   ?    factory
3.   ?    house
4.   ?    workshop

In order to prevent 'nuisance tripping' of the protective devices for circuits supplying equipment such as electrical welding sets and x-ray machines

1.   ?    the minimum size (mm²) of the circuit protective conductor should be 10 mm²
2.   ?    surge divertors should be fitted at each item of equipment
3.   ?    type D circuit breakers to BS EN 60898 should be fitted
4.   ?    cartridge fuses to BS 1361 type 1 should be fitted.

When designing supplies and circuitry for a large IT equipment complex, consideration must be given to

1.   ?    protective conductor currents
2.   ?    direct current feedback
3.   ?    fault leakage current
4.   ?    the creation of a non-conducting location.

The total number of fused spurs that may be connected into a domestic final ring circuit is

1.   ?    six
2.   ?    equal to the total number of socket outlets
3.   ?    equal to half the number of socket outlets
4.   ?    unlimited.

For household installations, the maximum floor area that may be served by a single 30 A ring final circuit using socket outlets to BS 1363 is

1.   ?    20 m²
2.   ?    100 m²
3.   ?    200 m²
4.   ?    unlimited.

An industrial type fuseboard supplies the following:

4 x 3 phase motors (TP)
2 x 3 phase space heaters (TP-N) 4 x single phase ring final circuits 2 x single phase lighting circuits.

Excluding the supply cables, the number of live conductors enclosed within the fuse board would be

1.   ?    21
2.   ?    28
3.   ?    32
4.   ?    40.

The required current carrying capacity of a three-phase circuit conductor has been determined as 22 A. Using the appropriate cable selection table, which one of the following is the correct minimum conductor size for three single-core thermoplastic-covered, heavy duty, mineral insulated cables (copper conductors and sheaths) installed in flat touching formation on a perforated cable tray?

1.   ?    1.0 mm²
2.   ?    1.5 mm²
3.   ?    2.5 mm²
4.   ?    4.5 mm²

The essential information required at the design stage of an electrical installation is the

1.   ?    purpose for which the installation is intended
2.   ?    nomination of the main contractor
3.   ?    nomination of the electrical contractor
4.   ?    duration of the contract.

Electric shock may occur through direct or indirect contact. Which one of the following statements identifies the difference between such conditions for electric shock?

1.   ?    Direct contact results from touching a live part, but indirect contact occurs when touching a part made live by a fault.
2.   ?    Direct contact results from touching a part made live only by a fault but indirect contact results from touching a live part.
3.   ?    Selection of BS 88 parts 2 & 6 circuit protective devices prevents direct contact, whereas BS EN 60309 socket outlets will offer protection against indirect contact.
4.   ?    Using a 230 V electric drill fitted with a three-core flexible cord will offer protection against direct contact, but a 230 V Class II electric drill will not offer protection against indirect contact.

To provide protection against electric shock Class II equipment relies on basic insulator and

1.   ?    bonding
2.   ?    connection of exposed metalwork to the protective conductor
3.   ?    precautions in the fixed wiring of the installation
4.   ?    supplementary insulation.

Class II electrical equipment will provide protection against

1.   ?    direct contact
2.   ?    indirect contact
3.   ?    short circuit
4.   ?    overloading.

The maximum permissible earth fault loop impedance on a TN system for a socket outlet, used for hand held equipment and protected by a 20 A fuse to BS 3036, is

1.   ?    1.10 Ω
2.   ?    1.78 Ω
3.   ?    1.85 Ω
4.   ?    2.70 Ω

In the event of an earth fault, the shock protection requirements of final circuits supplying stationary equipment are satisfied when disconnection occurs within

1.   ?    0.4 s
2.   ?    1.0 s
3.   ?    1.8 s
4.   ?    5.0 s.

To prevent the spread of fire where a wiring system passes through elements of building structures, any holes must be sealed. Which one of the following is not a requirement for such sealing materials? It

1.   ?    shall be compatible with the material of the wiring system.
2.   ?    shall prevent thermal movement of the wiring system.
3.   ?    shall be removable without damage to the existing cable.
4.   ?    shall resist relevant external influences to the same degree as the wiring system.

An overcurrent occurring in a circuit which is electrically sound is defined as

1.   ?    design current
2.   ?    overload current
3.   ?    shock current
4.   ?    short-circuit current.

The requirements for overload current protection are fulfilled when

1.   ?    Ib = 15A, In = 20A, Iz = 18A
2.   ?    Ib = 20A, In = 15A, Iz = 15A
3.   ?    Ib = 10A, In = 15A, Iz = 18A
4.   ?    Ib = 2.5A, In = 10A, Iz = 8A

A short-circuit current is defined as an overcurrent occurring in a circuit when a

1.   ?    heavy overload occurs
2.   ?    fuse blows
3.   ?    fault of negligible impedance occurs between phase conductors
4.   ?    fault occurs between phase and protective conductors.

A device intended, for reasons of safety, t cut off all or part of an installation from every source of electrical energy provides

1.   ?    functional switching
2.   ?    isolation
3.   ?    switching off for mechanical maintenance
4.   ?    emergency switching.

A section of a factory requires urgent non-electrical repairs to a machine. The type of switching provided to allow this work to proceed would be switching for

1.   ?    mechanical movement
2.   ?    mechanical maintenance
3.   ?    emergency
4.   ?    safe operation.

Under-voltage protection would be require where loss and subsequent restoration of voltage may cause the

1.   ?    unexpected operation of protective devices
2.   ?    burning out of lamps
3.   ?    unexpected restarting of machinery
4.   ?    malfunction of magnetic devices.

In a location where a risk of danger from fir exists due to manufacture or storage of combustible materials, enclosures of heaters shall not attain a surface temperature under normal working conditions exceeding

1.   ?    70°C
2.   ?    90°C
3.   ?    100°C
4.   ?    115°C.

For a.c., the preferred frequencies which are taken into account in BS 7671 are

1.   ?    25 Hz, 50 Hz and 60 Hz
2.   ?    50 Hz, 60 Hz and 400 Hz
3.   ?    25 Hz, 50 Hz and 250 Hz
4.   ?    50 Hz, 100 Hz and 400 Hz.

When cables are placed directly in the ground they should be buried at a depth

1.   ?    of not less than 0.5 m
2.   ?    of not less than 1.5 m
3.   ?    sufficient to avoid damage
4.   ?    sufficient to allow easy access.

In a conventional circuit arrangement where socket outlets are wired from a 13 A fused spur using flat thermoplastic (pvc) insulated cables with copper conductors the
minimum permissible conductor size is

1.   ?    1.0 mm²
2.   ?    1.5 mm²
3.   ?    2.5 mm²
4.   ?    4.0 mm².

In addition to any other correction factors that may be applied when determining the cable size for a circuit protected by semi-enclosed fuses to BS 3036, the
current rating of the fuse must be divided by

1.   ?    0.67
2.   ?    0.725
3.   ?    1.45
4.   ?    1.8.

A permanent warning notice must be fixed at or near the point of connection of every earthing conductor to an earth electrode. This notice must bear the words

1.   ?    Earth Bonding Connection, Do Not Remove
2.   ?    Safety Bonding Connection, Do Not Remove
3.   ?    Earth Electrical Connection, Do Not Remove
4.   ?    Safety Electrical Connection, Do Not Remove.

Metal enclosures for cables shall not be used as part of

1.   ?    a PEN conductor system
2.   ?    a circuit protective conductor system
3.   ?    a bonding system
4.   ?    an earth monitoring system.

The requirement that the metalwork of gas, water or other services is not to be used as a protective earth electrode does not preclude

1.   ?    its temporary use as an earth electrode
2.   ?    the permanent isolation of such metalwork
3.   ?    its use as an auxiliary earth electrode
4.   ?    the bonding of such metalwork as required.

In order to calculate the minimum value of the cross-sectional area of a protective conductor, the following information is available
Fault current = 400A, Operating time of protective device = 0.45 s Constant, k, for protective conductor material = 134

The selected cross-sectional area of the protective conductor should be

1.   ?    2.5 mm²
2.   ?    4.0 mm²
3.   ?    6.0 mm²
4.   ?    16 mm²

By employing an r.c.d. protected outlet to supply a Class II portable tool, the user is

1.   ?    protected against an earth fault in the windings of the tool
2.   ?    protected against breakage of the protective conductor of the flexible cable
3.   ?    protected against direct contact with a live conductor exposed by damage to the flexible cable
4.   ?    unable to operate the tool until the earthing circuit is complete and monitored.

Where a residual current device is used for the protection of portable equipment outside the equipotential zone, this type of protection is known as

1.   ?    auxiliary
2.   ?    supplementary
3.   ?    emergency
4.   ?    back-up.

An installation is supplied from a TT system. For such an installation all socket outlet circuits have to be protected by

1.   ?    a semi-enclosed (re-wireable) fuse
2.   ?    an earth monitoring device
3.   ?    a circuit breaker
4.   ?    a residual current device

The prospective fault circuit current at the origin of the consumer's installation must be taken into account when

1.   ?    estimating the external earth loop impedance
2.   ?    applying diversity factor to the installation
3.   ?    selecting the system of earthing for the supply
4.   ?    selecting the type of overcurrent protective device to be installed.

Cable couplers should be arranged so that the plug of the coupler is connected to

1.   ?    a circuit protected by a fuse
2.   ?    the load site of the circuit
3.   ?    a circuit having a circuit protective conductor
4.   ?    the supply side of the circuit.

A source for a safety service shall be supplied from a

1.   ?    rectifier
2.   ?    battery
3.   ?    capacitor
4.   ?    d.c. motor.

Which one of the following switching arrangements would not be suitable for preventing a standby generator from operating in parallel with a public supply system?

1.   ?    A system of locks with a single transferable key.
2.   ?    A three-position break-before-make changeover switch.
3.   ?    A three position make-before-break changeover switch.
4.   ?    An automatic changeover switching device with a suitable interlock.

In Zone 2 of a bathroom, wiring systems embedded in the walls at a depth not exceeding 50 mm shall be limited to those which supply fixed equipment in Zones

1.   ?    1 and 3
2.   ?    0, 1 and 2
3.   ?    0, 2 and 3
4.   ?    1, 2 and 3.

Equipment installed in Zone D of a hot air sauna shall be suitable for an ambient temperature of

1.   ?    70°C
2.   ?    90°C
3.   ?    125°C
4.   ?    180°C.

Which one of the following diagrams shows the correct arrangement for reduced low voltage supply for a construction site?

1.   ?    A
2.   ?    B
3.   ?    C
4.   ?    D

In agricultural premises, a residual current device may be used for protection against fire, providing the operating current does not exceed

1.   ?    30 mA
2.   ?    150 mA
3.   ?    300 mA
4.   ?    500 mA.

In a caravan park, the maximum number of socket outlets which can be protected by an rcd is

1.   ?    2
2.   ?    3
3.   ?    6
4.   ?    10.

To reduce the risk of shock from the metalwork of Class I street located equipment, protection should be by

1.   ?    non-conducting location
2.   ?    EEBAD
3.   ?    earth-free equipotential bonding
4.   ?    electrical separation

For a TT installation where a protective conductor current is likely to exceed 3.5 mA, the product of the total protective conductor current (in amperes) and twice the resistance of an installation earth electrode (in ohms) shall not exceed

1.   ?    25
2.   ?    50
3.   ?    100
4.   ?    200.

When carrying out an inspection in accordance with BS 7671, which one of the following must be inspected?

1.   ?    The presence of fire barriers.
2.   ?    The prospective short circuit current.
3.   ?    The maximum permissible voltage drop.
4.   ?    Site applied insulation.

A durable copy of a schedule relating to a distribution board should be

1.   ?    forwarded to the local supplier
2.   ?    submitted to the installation designer
3.   ?    kept within or adjacent to the distribution board
4.   ?    retained by the electrical contractor

The purpose of the integral test button of a residual current device is to check the

1.   ?    earth fault impedance
2.   ?    continuity of the earthing conductor
3.   ?    mechanical parts of the r.c.d.
4.   ?    earth electrode resistance.

Which one of the following tests should not be carried out with the supply on?

1.   ?    Insulation resistance.
2.   ?    Prospective fault current.
3.   ?    Earth fault loop impedance.
4.   ?    Operation of a residual current device.

For circuits having a nominal voltage above 500 V, the minimum insulation resistance is

1.   ?    0.25 MΩ
2.   ?    0.5 MΩ
3.   ?    1 MΩ
4.   ?    5 MΩ

No alteration, temporary or permanent, shall be made to an existing installation unless the

1.   ?    electricity supplier has been informed
2.   ?    local authority has been informed
3.   ?    existing equipment is adequate for any additional load
4.   ?    existing equipment meets BS and BS EN standards.

Before an Electrical Installation Certificate is issued for alterations or additions to any installation, any defects or omissions must be

1.   ?    recorded
2.   ?    reported to the person ordering the work
3.   ?    made good
4.   ?    noted for any future testing of the installation.

Which one of the following does not affect the frequency of periodic Inspection and Testing of an installation?

1.   ?    Formal qualifications of the Inspector.
2.   ?    The type of installation.
3.   ?    Frequency of maintenance.
4.   ?    Any external influences to which it is subjected.

Which one of the following numbers is the correct grouping factor for six circuits installed as method 3?

1.   ?    0.45
2.   ?    0.55
3.   ?    0.57
4.   ?    0.69

A 60 A BS 3036 protective device operates 5 seconds after a fault develops. The approximate value of fault current will be

1.   ?    30 A
2.   ?    60 A
3.   ?    205 A
4.   ?    500 A.

The reference for the installation method that has multicore cables having a non-metallic sheath, in surface mounted conduit, is

1.   ?    1
2.   ?    3
3.   ?    4
4.   ?    11