To which one of the following electrical installations does BS 7671 apply?
1. Installations at mines and quarries.
2. Caravans and their sites.
3. Public transmission systems.
4. Off-shore installations.
To which one of the following electrical installations does BS 7671 NOT apply?
1. Agricultural and horticultural premises.
2. Systems for transmission of energy to the public
3. Construction sites.
4. Caravans and their sites.
Which one of the following installations would NOT be within the statutory control of an authoritative body?
1. Petrol filling station.
2. Caravan site.
3. Theatre.
4. Domestic dwelling.
An a.c. voltage of 120 V between conductors is classified as
1. ELV
2. LV
3. SELV
4. RLVS
The type of distribution known as PME is a
1. TT system
2. TN system
3. TN-S system
4. TN-C-S system
BS 7671 low voltage a.c. between conductors as voltage
1. below 250
2. below 1000 but above 50
3. above 50 but below 500
4. above 250 but below 1000
A building constructed solely of wood would have an external influence category of
1. CA1
2. CA2
3. CA3
4. CA4
When considering the compatibility of a large three-phase a.c. motor, installed with other equipment within an installation, it is important to avoid
1. overvoltages occurring within the installation
2. undervoltages being created within the installation
3. high frequency oscillations
4. the neccessity for aditional connections to earth
An assessment MUST be made of the harmful effects upon other electrical services when installing
1. fluctuating loads such as welding transformers
2. automatic fire alarm circuits
3. emergency lighting circuits
4. SELV supplies
A final circuit is the wiring between
1. supply company's fuse and the energy meter
2. main switch and the distribution board
3. distribution board and current using equipment
4. supply company's fuse and the remotest outlet point
Distribution fuseboards for final circuits in large factories and commercial premises should be positioned
1. close together
2. in accessible positions
3. near to the centre of the loads
4. near to the supply intake
To take account of the Harmonic current that may be present in the three-phase and neutral cable supplying an office block having a large quantity of IT equipment, the designer may require
1. surge divertors to be fitted across each phase to neutral
2. discharge resistors to be fitted to each item
3. the mains cable to have two neutral cores included
4. protection of the supply cable by an r.c.d having an operating current of 500 mA.
When carrying out an installation supplied by a TN-C-S system, it is essential to consult the
1. Secretary of State for Energy or Secretary of State for Scotland
2. Local Electricity Supplier
3. Local Authority
4. Electricity Supply Regulations (1988).
Which one of the following is NOT a characteristic of the supply?
1. Nominal voltage
2. Frequency
3. Earth loop impedance
4. Emergency switching
Which one of the following situations may give rise to a risk of `Direct Contact'?
1. A 13 amp plug with a broken cover.
2. A metal bulkhead fitting which is secure, but ineffectively earthed.
3. A difference in ground potential adjacent to an earth electrode.
4. A steel conduit installation in which couplings and bushes are left loose.
An example of an exposed conductive part is a
1. water pipe
2. metal sinktop
3. gas pipe
4. metal switch plate
Protection against both direct and indirect contact can be provided by a SELV. One suitable safety source of supply would be a
1. 50 V storage battery
2. 230 V diesel generator
3. 230/110 V single-phase generator
4. 230/50 V auto-transformer.
Where a circuit forms part of a TN system, the maximum permissible earth fault loop impedance (Z,) for a 30 A socket outlet circuit used for portable equipment and protected by a 13S 1361 fuse is
1. 1.0 Ω
2. 1.2 Ω
3. 1.5 Ω
4. 2.0 Ω
In the event of an earth fault, the shock protection requirements of final circuits supplying 230 V stationary equipment are satisfied when disconnection occurs within
1. 0.4 s
2. 1.0 s
3. 1.8 s
4. 5.0 s
The result of the earth fault loop impedance (Zs) being higher than allowed in BS 7671 is that the
1. short-circuit current will not operate the protective device
2. current rating of the protective device must be increased
3. current rating of the protective device must be reduced
4. cable will be damaged before the protective device will operate under earth fault conditions
One item of electrical equipment likely to need additional protection against thermal effects is a
1. fluorescent luminaire
2. tungsten filament lamp luminaire
3. single pole dimmer switch
4. consumer unit housing rewirable fuses.
Omission of devices for protection against overload is NOT permitted for
1. secondary circuits of current transformers
2. circuits which supply fire extinguishing, devices
3. exciter circuits of rotating machines
4. circuits which supply emergency lighting
The nominal rating of an overcurrent protective device should be
1. not less than the design current
2. greater than the current carrying capacity of the conductors
3. 1.45 times the load current
4. equal to the prospective short-circuit current.
As a means of isolation in a circuit it is NOT permissible to use a
1. double-pole switch fuse
2. fireman's switch
3. linked switch
4. semi-conductor device
Which one of the following may be used to provide emergency switching for an electric motor?
1. A key switch latched in the ON position.
2. A plug and socket outlet.
3. A switch fuse with a removable handle.
4. A device which latches in the OFF position.
Suitable precautions shall be taken where either a reduction in voltage or a loss and subsequent restoration of voltage
1. is a routine event
2. could cause danger
3. occurs infrequently
4. will not cause danger.
Within a paper mill having a conduit wiring system, insulation fault protection must be provided using an RCD having a residual operating current not exceeding
1. 30 mA
2. 300 mA
3. 500 mA
4. 750 mA
Which one of the following is NOT a classification of external influences?
1. Current rating
2. Environmental conditions.
3. Construction of building.
4. Utilisation.
Fig. 1 shows a run of 20 mm rigid insulating conduit. The maximum distance between horizontal and vertical supports respectively is
1. 0.75 m : 1.99 m
2. 1.5 m : 1.75 m
3. 1.75 m : 2.00 m
4. 2.00 m : 2.00 m
If a cable is totally enclosed in Thermal Insulation for a distance of 2 m, the correction factor (C) will be
1. 0.5
2. 0.55
3. 0.68
4. 0.81.
Diversity factors may be applied to a circuit which is
1. not expected to be continually fully loaded
2. designed to carry its maximum load continually
3. supplying thermostatically controlled water heaters
4. supplying thermal storage heaters
Where an installation incorporates an r.c.d., the label at the origin of the installation must indicate that the maximum period between tests on the r.c.d. is
1. quarterly
2. half-yearly
3. annually
4. bi-annually
All fuses and circuit breakers shall have an indication of the
1. name of the manufacturer
2. intended application
3. model or BS number
4. intended nominal current.
Where a TT system is in use, the preferred protective device is a
1. residual current device
2. circuit breaker
3. cartridge fuse link
4. disconnecter.
Which one of the following is excluded as a protective earth electrode?
1. Underground structural metalwork embedded in foundations.
2. Welded metal reinforcement of concrete embedded in the earth.
3. Earth plates.
4. Metalwork of public water services
A steel earthing conductor mechanically protected, but not protected against corrosion is buried in soil. The minimum size of the earthing conductor is
1. 4.0 mm²
2. 16 mm²
3. 25 mm²
4. 50 mm²
For a general domestic installation connected to a TT or TN system, and protected by a residual current device, the product of the rated residual current ( I∆n) and the earth fault loop impedance (Zs ) shall NOT exceed
1. 0.5 V
2. 5V
3. 50 V
4. 500 V.
Where a socket outlet of rating 32 A or less is used to supply portable equipment outdoors, supplementary protection to reduce direct contact risk must be provided by means of a
1. fuse having a suitable time/current characteristic
2. Type B circuit breaker to BS EN 60898
3. residual current device having the specified characteristics
4. switch-disconnector to BS EN 60947-3.
Socket outlets supplying 230 V equipment used in the garden MUST be protected by a residual current device. This device is fitted because the equipment is being used
1. within the equipotential zone
2. where the earth loop impedance Z, is above 500 Ω
3. where the overload tripping time exceeds 5 seconds
4. outside the equipotential zone.
In order to reduce the effects of eddy currents when conductors enter a ferrous enclosure, they should be so arranged that
1. each conductor of an individual circuit takes approximately the same value of current
2. they are not individually surrounded by the ferrous material
3. they are terminated in the correct phase sequence
4. they are physically separated from conductors of other circuits within the enclosure.
Starters incorporating overcurrent protection must be provided for electric motors having a rating exceeding
1. 3.7 W
2. 37 W
3. 0.37 kW
4. 3.7 kW.
A non flame propagating wiring system having a maximum internal cross-section of 710 mm²
1. need not be internally sealed
2. must be internally sealed
3. need only be sealed if passing through an insulating partition
4. must be internally sealed if passing through a brick wall.
Electrical equipment installed in Zones 1, 2 and 3 of communal baths or communal showers, where water jets are likely to be used for cleaning purposes, shall have a minimum degree of protection against external influences of
1. IPX3
2. IPX4
3. IPX5
4. IPX6.
The minimum protection required for SELV equipment in a hot air sauna room is
1. IP24 or IPX4B
2. IPX5 or IP55
3. IPX3 or IP3X
4. IP2X or IPXXB
Where the rating of fixed and movable plant on a construction site is above 3.75 kW, the supply voltage must NOT exceed
1. 50 V
2. 110 V
3. 230 V
4. 400 V.
In agricultural premises, heating appliances shall be fixed so as to maintain an appropriate distance from livestock. In the absence of manufacturer's guidance, a radiant heater used in the vicinity of livestock should be placed at a distance of NOT less than
1. 0.5 m
2. 1.5 m
3. 2.0 m
4. 2.5 m
In an area where there is no vehicle movement on a caravan park, the minimum height for overhead cables is
1. 3.5 m
2. 6.0 m
3. 7.5 m
4. 8.0 m.
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
In 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 legible diagram, chart or table relating to an installation must be provided to indicate the
1. route followed by each circuit
2. earth fault loop impedance of the supply
3. capacity of each distribution board
4. type and composition of each circuit
An r.c.d. protected socket outlet circuit is connected to a TT earthing system. Operating the r.c.d.'s integral test button will verify
1. the continuity of the main earthing conductor
2. the effectiveness of the earth electrode
3. the continuity of final circuit protective conductors
4. that the internal mechanism of the device operates
Where a given test result fails to comply with BS 7671 Part 7, the procedure to adopt after the fault has been rectified is that
1. the test and those that follow should be repeated
2. the whole sequence of tests should be repeated
3. only the test that indicated the fault should be repeated
4. the test that indicated the fault and those tests which may have been influenced by the fault that preceded it should he repeated
When testing a 230 V installation, the minimum value of insulation resistance to earth with all fuses in place and all the phase conductors connected together is
1. 0.5 Ω
2. 1 Ω
3. 0.5 MΩ
4. 1 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 lead
4. existing equipment meets BS and BS EN standards
On completion of a new installation, an electrical Installation Certificate should be signed by
1. the owner or manager of the factory
2. a competent person or persons
3. the legal department representing the owner of the premises
4. the main building contractor.
The frequency of periodic inspection and testing for an installation shall be determined by the
1. supply company recommendations
2. installation's maximum demand
3. nature of the supply
4. type of installation.
When carrying a fault current of 205 A, a 60 A protective device to BS 3036 should operate in
1. 0.1 s
2. 0.4 s
3. 5.0 s
4. 500 s.
The external influence having a classification of AD7 indicates
1. humidity
2. immersion in water
3. dust in the atmosphere
4. high levels of vibration.
A Minor Works Certificate should be issued
1. when an additional circuit is connected to an existing installation
2. for new installations connected to single phase supplies of 100 A or less
3. for alterations or additions that do not
  extend to the provision of a new circuit
4. for new installations limited to domestic applications only

City & Guilds 2381 - Sample Paper 2