Based on C&G2382 - BS7671:2018 (Amendment 2:2022) Electrical Regulations Mock Exam (FULL MOCK: 60 questions - 120 minute time limit)
BS7671 Electrical regulations mock test (use Amendment 2:2022 regs book) - 60 questions from a large question bank (to be completed within 120 minutes time limit). Regs book answer locations shown in feedback, (hint often provided if you choose wrong answers).
The choice of the type of wiring system and the method of installation shall consider all except
Load current
Nature of the location
Voltage
Short-circuit current
Equipment may not be fixed
On covers which can inadvertently be removed
On equipment mouldings
On or in skirting-board trunking
On or in steel cable trunking
When conductors are identified by the number zero, it;
Identifies the neutral conductor
May not be used
Identifies the protective conductor
Identifies the line conductor
Potential sources of electromagnetic disturbances include all except for
Batteries
Rectifiers
Electric motors
Discharge lighting
Where protection is provided against overload and not fault current the device providing protection may be
an Inverse time lag protective device
a 30mA RCD
a BS 88-2 fuse
a RCD with a maximum rating of 300mA
A 1500V DC voltage between conductors is classified as being
Band II
Band I
ELV extra low voltage
RLV reduced low voltage
An interrupting device shall be installed in such a way that it can be easily recognised and effectively operated where necessity for immediate interruption of the supply, is termed as
Emergency control
Environmental condition
Accessibility of electrical equipment
Protective equipment
For a shower installed without a basin
Zone 1 is increased to 1.20m
Zone 2 applies
Zone 2 is 0.6m from the water-outlet
Zone 0 does not apply
For a construction site, reduced low voltage is the preferred protection method for all except
Portable hand lamps in confined locations
Portable hand lamps
Local lighting up to 2kW
Portable hand tools
Three phase 4-wire system including a PEN conductor has only
Three live conductors
Four live conductors
Two live conductors
Three conductors
Maintainability should be a consideration when assessing
The reliability of equipment
Installation erection scheduling
The cost of repair
The time taken for repair
For Electric Vehicle charging, Mode 2 charging socket-outlets should not exceed
32A
13A
20A
16A
During inspection of a part of an installation that requires testing that part shall normally
Be disconnected from the supply
Have current using equipment operating
Be connected to the normal supply
Have current using equipment connected
Any intended departure from BS 7671
Shall not result in a degree of safety less than that when complying with BS 7671
Is not allowed
May lessen the resulting degree of safety
Does not need to be noted on the electrical test certificate
A supplementary bonding conductor with mechanical protection connecting two extraneous-conductive parts shall have a minimum c.s.a. of mmsq
2.5
4.0
1.5
16
Where screened signal cables are common to several buildings supplied from a TT system, a copper bypass equipotential bonding conductor shall have a minimum c.s.a. of
16 mmsq
10 mmsq
6 mmsq
25 mmsq
The co-ordination between fault current and overload protective devices is that the overload protective device can withstand without damage
The energy let through by the fault current protective device
The overload current of the circuit
The nominal voltage rating of the fault current protective device
The design current of the circuit
When a PEI is in island mode, all live conductors shall be
Disconnected from the DNO supply
Switched independently
Connected to the public supply
Connected in parallel with the public supply
The Maximum earth fault loop impedance Zs for a BS 3036 fuse rated at 30A and 0.4s disconnection time is
1.04 ohms
2.2 ohms
1.77 ohms
2.68 ohms
Which one of the following is not a characteristic of the supply
The nature of fault and harmonic currents
Frequency
Prospective short-circuit current
Earth fault loop impedance external to the consumer's TN installation
BS 7671 states that installations shall have an adequate level of immunity against
Electromagnetic disturbances
Unexpected circumstances
Flooding
Earth tremors
RCD for the protection against the risk of fire shall have a rating not exceeding
300mA
30mA
10mA
100mA
For device coordination between upstream fuse and downstream circuit breaker the following condition should apply
the minimum pre-arcing I(sq) t value of the fuse should be higher than the maximum let through I(sq) t value of the circuit breaker.
the peak let-through current of the fuse should be lower than the instantaneous tripping current of the circuit breaker.
the minimum pre-arcing I(sq) t value of the circuit breaker should be higher than that of the fuse.
selectivity in case of short circuit is verified by comparison of the I(sq) t values on the inlet side.
For an IT installation supplying offices harmonic currents in a three phase circuit may require
An increased c.s.a for the neutral conductor
Insulation monitoring devices
An RCD rated at 400mA
Use of a separate protective device for each circuit
Protection against transient overvoltages shall be provided where the consequence caused by overvoltage could result in all except
Affect a small group of co-located individuals
Interruption of commercial activity
Interruption of public services
Serious injury
A single-core 90degC thermosetting cable has an aluminium conductor. For the calculation of the effects of fault current for a disconnection time up to 5s the value of K is
94
115
197
88
Protective devices against undervoltage are selected as follows except
Voltage harmonics
Indirect operating undervoltage release
Automatic re-closing when the voltage is restored
Direct operating undervoltage release
A firefighter's switch shall be installed at a height from the ground not more than 2.75m with
ON and OFF positions in letters not less than 10mm high
Labelling visible
The unit coloured yellow
lockable ON position
A cable coupler shall be arranged so that the connector of the coupler is fitted to
The end of the cable remote from the supply
A system providing mechanical protection
The supply side of the circuit
A system that is protected by a fuse
Where a residual current monitor RCM is installed downstream of an RCD the RCM is recommended to have a rated residual actuating current not exceeding
0.5 of the RCD
0.66 of the RCD
0.33 of the RCD
Tth rated value for the RCD
A detailed inspection of an installation prior to testing is required to verify that installed equipment is satisfied all except
Suitable for minimum test values
Correctly selected and erected
In compliance with Section 511
Not visibly damaged or defective
Which one of the following is not characteristic of the supply
The nature of fault and harmonic current
Frequency
Earth fault loop impedance external to the consumer's TN installation
Prospective short-circuit current
The connecting cable to a caravan pitch socket-outlet shall be with an allowance of 2m a maximum continuous length of
25m
15m
10m
35m
For high density livestock rearing life support system shall take into account all except
Means of monitoring peak energy demand
A secure source of back-up supply
Temperature and supply voltage monitoring where power ventilation is necessary
Selectivity of the main circuits supplying ventilation
For thermosetting insulated cable buried direct in the ground with an ambient temperature of 10 degC the appropriate rating factor to be used is
1.07
1.02
1.12
0.9
For a ring final circuit protected by 32A overcurrent protective device BS 7671 states as a rule of thumb that the total floor area being served is limited to
100 metres squared
75 metres squared
50 metres squared
125 metres squared
Diversity can be considered in a circuit which is
Not expected to be fully loaded continually
Carrying it's maximum load continually
Supplying night operating storage heaters
Not in constant use as designed to be a back-up supply circuit
When deciding on the frequency of maintaining an installation during it's intended life which one of the following is not essential requirement
The reliability of equipment should have a life of at least 10 years
Any protective measures for safety remain effective and not diminished
The person or body responsible for the operation/maintenance shall be consulted
Any periodic inspection and testing may be readily and safely carried out
For a bare (105 degreeC) M.I cable operating in an ambient temperature of 50 degC the rating factor Ca to be used is
0.84
0.8
0.75
0.91
Testing by the method of simulating a fault condition would be used when testing
An RCD
Earth electrode resistance
Insulation of non-conducting floor
Insulation resistance
When it's not reasonably practicable to disconnect surge protective devices when testing insulation resistance the test voltage used for a 230V circuit and the minimum acceptable value of insulation resistance is
250V DC 1M ohms
250V DC 0.5M ohms
B 250V DC 0.1M ohms
500V DC 0.5M ohms
In Zone 3 of a hot air sauna equipment must withstand a minimum temperature of 125degC while insulation and sheaths of cables must withstand a minimum temperature of degC
170
150
165
155
For marinas and seashore locations the minimum degree of protection for equipment installed on a pier against water slashes and ingress of small objects is
IPX4 and lP3X
IPX6 and IP3X
IPX4 and IP2X
IPX6 and IP2X
For energy efficiency the designer should take into account all the following except
Efficiency of protective devices
Reduction of energy losses
Use of energy
Load energy profile
In locations where there are risks of fire due to the nature of processed or stored materials the enclosures of electrical equipment shall be prevented from exceeding under fault conditions the temperature degC is
115
95
85
100
For a 400V installation with Category III equipment the required minimum rated impulse voltage in kV for overload protection is
6
2.5
10
4.0
Copper conductors between Type 1 SPDs and the OCPDs to live conductors shall have c.s.a not less than
6 mmsq
10 mmsq
16 mmsq
4 mmsq
When selecting a SPD for protection which one of the following is not a parameter to be considered
Earth leakage current
Voltage protection level
Continuous operating voltage
Nominal discharge current
A steel earthing conductor is buried in soil. It is neither protected against corrosion or mechanical damage. It's minimum cross-sectional area shall be
50 mmsq
40 mmsq
35 mmsq
25 mmsq
Supplementary bonding conductors without mechanical protection connecting exposed or extraneous-conductive parts shall have a minimum c.s.a. of
4 mmsq
2.5 mmsq
6 mmsq
1.5 mmsq
the CENELEC European standards harmonization, for post 1995, sets the permitted tolerance of voltage at
+10%/-6%
+10%/-10%
+6%/-6%
+6%/-10%
Emergency lighting shall comply with the following BS standard
BS5266
BS3676
BS5839
BS7375
Fire Alarm systems shall comply with the following BS standard
BS5839
BS3676
BS5266
BS7375
Relating to technical issues for Prosumer electrical installations, combined short circuit protection shall take account of all possible fault current magnitudes except
Conductor insulation values
Various operating modes
Location of fault
Possible combinations of power supplies
A building having the shape and dimensions which facilitate the spread of fire has a classification
CB2
BE1
BA1
CA2
A single-pole switching device may switch only the neutral conductor for
Connection of a lighting control device
PELV circuits
RCD protected circuits
SELV circuits
Means for emergency switching off shall be
One single action
Appropriately coloured
Clearly labelled
Resettable
BS 7671 defines gangways with restricted access as having all except
Yellow warning markings
Marking by appropriate signs
Doors which allow easy evacuation
No access to unauthorised persons
To which one of the following AC circuits does a maximum disconnection time of 5s apply
TN-C-S system 230v 40A circuit
TT system 400v 32A circuit
TT system 230v 6A circuit
TN-S system 400v 16A
To which one of the following AC circuits does a maximum disconnection time of 1s apply
TT system 16A distribution circuit
TT system 230v 16A circuit
TN-C-S system 63A distribution circuit
TN-S system 400v 16A
To which one of the following AC circuits does a maximum disconnection time of 0.4s apply
TN-S system 230v 16A circuit
TT system 230v 32A circuit
TN-C-S system 63A distribution circuit
TN-S system 400v 40A circuit
To which one of the following AC circuits does a maximum disconnection time of 0.2s apply
TT system 230v 16A circuit
TN-C-S system 230v 32A socket circuit
TN-C-S system 63A distribution circuit
TT system 230v 40A circuit
The cross-sectional area of conductors shall be determined by each of the following except
The earthing system
The maximum temperature
The electromagnetic stresses
The admissible voltage drop
BS 7671 states the nature of demand is determined by knowledge of all except
Averaged hourly demand
Daily and yearly variation of demand
Special conditions (harmonics)
Anticipated future demand if specified
An accessory with female contacts attached to the end of a flexible cable remote from the supply is known as
Connector
Plug
Electrode
Adaptor
Agricultural and horticultural premises as defined in BS 7671 include all except
Farmhouse
Cattle sheds
Greenhouses
Animal products storeroom
Which one of the following is not characteristic of the supply for a installation
The earth fault loop impedance of a TN system
External Impedance
The prospective short-circuit current at the origin of the installation
The nature of the current and frequency
Which one of the following is not an appropriate source for safety services
Fused spur on a ring circuit
Primary cells
Storage batteries
Separate independent electrical supply feeder
When protecting against undervoltage any delay in the opening or re-closing of a contactor shall not impede instantaneous disconnection by
A control device or a protective device
A surge device
Discrimination
A manual isolator
Where particular risks of fire exist due to the nature of stored materials and in the presence of dust, every luminaire shall be provided with an enclosure
With a degree of protection of at least IP5X
Class 2 rating
With a degree of protection of at least IP4X
Class 1 rating
A device not suitable for emergency switching is
Plug and Socket
Remote control of Circuit breakers
Manually operated switching devices
Combination of single action devices
For Prosumer installations combined short-circuit protection, the designer must take all the following into account excluding
use of the installation
location of the fault
combination of power supplies connected
various operating modes
In Prosumer installations, readings taken with an Earth Fault Loop Impedance tester may be adversely affected by which on of the following specific items of equipment
Inverters
electric car chargers
large motors
electric power meters
Determination of Ring and Radial circuit arrangements can be found in Appendix
15
14
11
10
A two-core 4.0mmsq 70 degC thermoplastic insulated armoured cable is installed using reference method C, supplying 230V 30A with circuit of length 10 metres. The calculated voltage drop is
3.3v
6.5v
3.8v
6.9v
For energy efficiency the designer should consider all of the following except
Time efficiency during installation
Determination of load profile
Power factor correction
Cross-sectional area of conductors
For the classification of external influences, the code for Fauna hazard is
AL2
CB2
AN2
AM2
For a bathroom, supplementary protective equipotential bonding may be installed in the bathroom
Either inside or outside preferably close to the point of entry of extraneous-conductive parts
Shall not be installed with a RCD protected circuit
Only inside
Only outside
For a PV system, a Type 1 SPD Impulse current shall be
not less than 12.5kV
less than 125kV
less than 12.5kV
more than 125kV
Every installation before being put into service should be given a
Inspection and test to verify compliance with regulations