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WorksheetsElectrical Safety Quiz CH41
Total questions: 90
Worksheet time: 48mins
What is the fundamental rule of protection against electric shock according to BS EN 61140?
Hazardous-live parts shall be accessible and hazardous-live under normal conditions.
Hazardous-live parts shall not be accessible and accessible conductive parts shall be hazardous-live under normal conditions.
Hazardous-live parts shall not be accessible and accessible conductive parts shall not be hazardous-live, both under normal conditions and under single fault conditions.
Hazardous-live parts shall be accessible but not hazardous-live under single fault conditions.
According to 4.10.1 of BS EN 61140, what does protection under normal conditions involve?
Fault protective provisions only.
Basic protective provisions and fault protective provisions.
Enhanced protective provision only.
No specific provisions are required under normal conditions.
What does Chapter 41 specify regarding protection against electric shock?
It specifies the types of electrical installations only.
It specifies the requirements for the application and coordination of additional protection in certain cases.
It specifies the requirements for the application and coordination of basic protection and fault protection of persons and livestock.
It specifies the requirements for the application of enhanced protective provisions under single fault conditions.
Which of the following is NOT a permitted condition for protective measures under the external influence according to 410.3.3?
Automatic disconnection of supply.
Double or reinforced insulation.
Electrical separation for the supply to one item of current-using equipment.
Use of non-insulated equipment.
What is the commonly used protective measure in electrical installations?
Reinforced insulation.
Extra-low voltage (SELV and PELV).
Automatic disconnection of supply.
Manual disconnection of supply.
According to Section 410.3.5, who is allowed to use the protective measures specified in Section 417?
Any person
Skilled persons only
Skilled persons or persons under the supervision of skilled persons
Unskilled persons
What can be omitted for fault protection according to 410.3.9?
Metal supports of overhead line insulators attached to the building and out of arm's reach
All exposed-conductive-parts
Basic insulation of live parts
Supplementary bonding connections
What is NOT a requirement for basic protection as per 411.2?
Compliance with one of the provisions for basic protection described in Section 416
Use of Class II equipment
Automatic disconnection of supply
Protective earthing
What does an RCM produce when a preselected value of residual current is reached, as noted in the NOTE under 411.1?
A visual signal only
An audible signal only
Both an audible and visual signal
A physical disconnection of the circuit
Which of the following is NOT listed as an example of extraneous-conductive-parts in Regulation 411.3.1.2?
Metallic water installation pipes
Metallic gas installation pipes
Overhead metallic structural parts of the building
Plastic water installation pipes
According to the note in Regulation 411.3.1.2, when are non-metallic pipes within a building that are connected to metallic pipes unlikely to require protective bonding?
When they enter a building and are not connected to metallic pipes
When they are used for gas installation only
When they do not normally require protective bonding as they are unlikely to be extraneous-conductive-parts
When they are connected to the main earthing terminal
What must be obtained if an installation serves more than one building and the above requirement shall be applied to each building, as per the text?
Consent of the owner or operator of the cable
A detailed report of the installation
Approval from the local government
A new cable installation permit
What is the maximum disconnection time stated in Table 41.1 for final circuits with a rated current not exceeding 32 A supplying only fixed connected current-using equipment?
There is no maximum disconnection time specified
The same as for circuits with a rated current of 63 A with one or more socket-outlets
It is not specified in the provided text
It is provided in Regulation 411.3.2.2
What is the maximum disconnection time for a TT system with a voltage over 400 V AC?
0.2 s
0.1 s
1.0 s
5.0 s
In a TN system, what is the maximum disconnection time allowed for a distribution circuit for a voltage between 230 V and 400 V AC?
1 s
5 s
0.2 s
0.4 s
According to the table, for which system is disconnection not required for protection against electric shock but may be required for other reasons, such as protection against thermal effects?
TN
TT
Both TN and TT
Neither TN nor TT
What additional protection is required for socket-outlets with a rated current not exceeding 32 A in locations where they are liable to be used by persons of any age, by BA1, BA3 or children (BA2, BA3)?
RCD with a rated residual operating current not exceeding 30 mA
RCD with a rated residual operating current not exceeding 32 A
RCD with a rated residual operating current not exceeding 5 s
No additional protection is required
Which of the following is an exception to the requirement of additional protection by means of an RCD for socket-outlets used outdoors?
Socket-outlets with a rated current not exceeding 32 A in other locations
Mobile equipment with a rated current not exceeding 32 A for use outdoors
Socket-outlets where a suitably documented risk assessment undertaken with the involvement of a skilled person (electrically) determines that RCD protection is not necessary
All socket-outlets require RCD protection without exception
For circuits with luminaires in domestic (household) premises, what is the rated residual operating current not to be exceeded for the RCD providing additional protection?
30 mA
32 A
5 s
100 mA
What is the primary factor on which the integrity of the earthing of the installation in a TN system depends?
The type of electrical devices used
The reliability and effective connection of the PEN or PE conductors to Earth
The distance between the electrical installation and the power supply
The brand of the electrical installation components
In a TN system, if the neutral point or midpoint of the power supply system is not available or accessible, what should be done?
A protective device should be installed
A line conductor should be earthed
The system should be converted to a different type of earthing system
The installation should operate without earthing
Under what condition can a single conductor serve both as a protective conductor and as a neutral conductor in a fixed installation?
If the installation is in an outbuilding of a dwelling
If the requirements of Regulation 543.4 are satisfied
If the installation uses RCDs exclusively for fault protection
If the installation is temporary
What is Zs in the context of the characteristics of the protective devices and circuit impedances?
The minimum voltage factor
The nominal AC rms or ripple-free DC line voltage to Earth
The impedance in ohms (Ω) of the fault loop comprising
The protective conductor between the point of the fault and the source
Which of the following types of protective device may be used for fault protection according to Regulation 411.4.5?
A fuse
An RCD
An overcurrent protective device
Both B and C
An RCD shall not be used in which type of system?
TN-S system
TN-C-S system
TT system
TNC system
What is the maximum value of earth fault loop impedance Zs used to satisfy the requirements of Regulation 411.3.2.2, assuming a nominal voltage (Uo) of 230 V AC, corresponding to a disconnection time of 0.4 s?
1.0 Ω
2.0 Ω
0.35 Ω
0.8 Ω
What is the correct value of Zs (ohms) for a general purpose (gG) circuit application with a rating of 10 amperes according to Table 41.2-?
4.65
2.43
1.68
7.80
According to Table 41.2-, for fuses to BS 88-3 fuse system C with a rating of 45 amperes, what is the maximum earth fault loop impedance (Zs) allowed?
0.57
0.91
0.36
1.93
For fuses to BS 3036 with a rating of 60 amperes, what is the value of Zs (ohms) as per Table 41.2-?
0.40
1.04
0.56
2.43
What is the Zs (ohms) value for fuses to BS 1362 with a rating of 13 amperes according to Table 41.2-?
15.6
2.30
1.68
0.56
What is the maximum earth fault loop impedance (Zs) for a Type B circuit-breaker rated at 32 amperes according to BS EN 60989?
1.37 ohms
0.87 ohms
0.69 ohms
0.55 ohms
According to BS EN 61009-1, what is the maximum earth fault loop impedance (Zs) for a Type C RCBO rated at 63 amperes?
0.35 ohms
0.22 ohms
0.55 ohms
0.44 ohms
For a Type D circuit-breaker of 10 amperes rating, what is the maximum earth fault loop impedance (Zs) as per BS EN 60989?
1.82 ohms
1.09 ohms
0.68 ohms
0.55 ohms
What is the correct Cmin value used to determine the maximum earth fault loop impedance (Zs) values in Table 41.3?
(a)
According to the note in Table 41.3, when should the circuit loop impedances not exceed the values given in the table?
When the line conductors are at the appropriate maximum permitted operating temperature.
When the line conductors are at the initial assumed temperature.
When the line conductors are at a different temperature than tested.
When the line conductors are at the appropriate assumed initial temperature.
What is the maximum earth fault loop impedance (Zs) for a general purpose (gG) fuse rated at 10 amperes according to BS 88-2 - fuse systems E (bolted) and G (clip in)?
12 ohms
6.8 ohms
4.0 ohms
2.8 ohms
For fuses to BS 88-3 fuse system C rated at 5 amperes, what is the maximum earth fault loop impedance (Zs) value?
3.9 ohms
14.6 ohms
1.6 ohms
3.2 ohms
According to the table, what is the maximum earth fault loop impedance (Zs) for fuses to BS 3036 rated at 20 amperes?
1.51 ohms
2.51 ohms
3.64 ohms
1.07 ohms
What is the correct maximum earth fault loop impedance (Zs) for a fuse rated at 3 amperes to BS 1362?
13 ohms
22.0 ohms
3.64 ohms
16.8 ohms
According to Note 2, when should the circuit loop impedances given in the table not be exceeded?
When the circuit conductors are at the appropriate maximum permitted operating temperature.
When the circuit conductors are at a temperature below the maximum permitted operating temperature.
When the circuit protective conductors are at the appropriate assumed initial temperature.
When the circuit protective conductors are not at the appropriate assumed initial temperature.
What types of protective device shall be used according to 411.5.2, with one being preferred over the other?
A fuse and an RCD
An RCD and an overcurrent protective device
An overcurrent protective device and a voltage regulator
A voltage regulator and an RCD
According to 411.5.3, what is the maximum value of R_A x I_Δn for the disconnection time to be compliant?
50 V
100 V
200 V
230 V
What is the maximum earth fault loop impedance Z_s for a rated residual operating current of 300 mA for non-delayed and time delayed 'S' Type RCDs to BS EN 61008-1 and BS EN 61009-1 for U_0 of 230 V, as shown in Table 41.5?
1667 ohms
167 ohms
500 ohms
100 ohms
What should Z_s be less than or equal to, according to 411.5.4, when an overcurrent protective device is used?
I_a x U_0 x C_min
R_A x I_Δn
U_0 x C_min
I_Δn x C_min
What is the value of C_min for a low voltage supply given in accordance with the Electricity Safety, Quality and Continuity Regulations as amended?
0.95
0.90
0.85
0.80
In an IT system, live parts shall be insulated from Earth or connected to Earth through what means to handle a high impedance fault?
A) A sufficiently high resistance
B) A direct connection to the neutral point or midpoint of the system
C) An artificial neutral impedance
D) All of the above
According to Regulation 411.6.2, what is the maximum touch voltage limit in AC systems to ensure safety?
A) 25 V
B) 50 V
C) 75 V
D) 100 V
Which of the following monitoring devices and protective devices may be used in IT systems according to 411.6.3?
A) Insulation monitoring devices (IMDs)
B) Residual current monitoring devices (RCMs)
C) Insulation fault location systems (IFLS)
D) All of the above
If an IT system is designed not to disconnect in the event of a first fault, what should indicate the occurrence of the first fault?
A) An insulation monitoring device (IMD)
B) A residual current monitor (RCM)
C) A visual and/or audible alarm system
D) A communication protocol
What additional system may be provided to indicate the location of a first fault from a live part to exposed-conductive-parts or Earth according to 411.6.4?
A) An insulation fault location system according to BS EN 61557-9
B) A residual current device (RCD)
C) A touch voltage limitation device
D) A direct current system
What is the nominal voltage not exceeding for Functional extra-low voltage (FELV) systems in AC and DC respectively?
50 V AC or 120 V DC
25 V AC or 60 V DC
100 V AC or 240 V DC
75 V AC or 150 V DC
According to the document, for what reason might the combination of provisions be known as FELV?
Because it is used for high voltage circuits only
Because it is used for remote-control services
Because it is used for circuits containing equipment such as transformers, relays, remote-control switches, contactors insufficiently insulated with respect to circuits at a higher voltage
Because it is used for circuits that are fully insulated and do not require any additional protection
What is the maximum resistance (in ohms) allowed between the earth electrode and the protective conductor to the exposed-conductive-parts for automatic disconnection of the protective device to occur?
0.5 Ohms
1 Ohm
5 Ohms
10 Ohms
What does the factor 2 in the formulae take into account in the event of the simultaneous occurrence of two faults?
The need for a faster disconnection time
The possibility of a fault in a different circuit
The simultaneous occurrence of two faults, the fault may exist in different circuits
The resistance of the protective conductor
What should basic protection be provided by according to Regulation 411.8.2 for reduced low voltage systems?
Basic insulation according to Regulation 416.1 corresponding to the maximum nominal voltage of the reduced low voltage system given in Regulation 411.8.1.2.
Barriers or enclosures in accordance with Regulation 416.3.
Automatic disconnection of supply as described in Regulation 411.3 to 411.6.
A transformer with at least simple separation between windings as per Regulation 414.3.
What is the maximum nominal voltage of reduced low voltage circuits according to Regulation 411.8.1.2?
110 V AC rms between lines (three-phase 63.5 V to earthed midpoint).
55 V AC rms between lines (three-phase 63.5 V to earthed midpoint).
110 V AC rms between lines (single-phase 55 V to earthed midpoint).
55 V AC rms between lines (single-phase 55 V to earthed midpoint).
What is the disconnection time for fault protection by automatic disconnection of supply in reduced low voltage systems according to Regulation 411.8.3?
The disconnection time does not exceed 1 s.
The disconnection time does not exceed 5 s.
The disconnection time does not exceed 7 s.
The disconnection time does not exceed 10 s.
According to Regulation 411.7.5, what must every plug, socket-outlet, luminaire supporting coupler (LSC), device for connecting a luminaire (DCL) and cable coupler in a FELV system have?
A protective conductor contact and be dimensionally compatible with those used for any other system in the same premises.
A protective conductor contact and not be dimensionally compatible with those used for any other system in the same premises.
No protective conductor contact and be dimensionally compatible with those used for any other system in the same premises.
No protective conductor contact and not be dimensionally compatible with those used for any other system in the same premises.
According to TABLE 4.1.6, what is the maximum earth fault loop impedance (Zs) for a 3-phase circuit with a 20 ampere rating and a disconnection time and Uo of 63.5 V?
0.60 ohms
0.34 ohms
0.30 ohms
0.77 ohms
What is the maximum earth fault loop impedance (Zs) for a single-phase circuit with a 32 ampere rating and a disconnection time and Uo of 55 V as per TABLE 4.1.6?
0.16 ohms
0.38 ohms
0.42 ohms
0.48 ohms
As per the notes in the document, the circuit loop impedances are determined using a value for factor Cmin of:
0.95
0.90
0.85
1.00
Which of the following is NOT a source of supply to a reduced low voltage circuit as mentioned in section 411.8.4?
A double-wound isolating transformer complying with BS EN 61558-1 and BS EN 61558-2-23
A motor-generator set having windings providing isolation equivalent to that provided by the windings of an isolating transformer
A source independent of other supplies, e.g., an engine-driven generator.
A single-wound transformer with no isolation properties
What is the purpose of double or reinforced insulation according to section 412.1.1?
To allow any change that could impair the effectiveness of the protective measure.
To provide basic protection by basic insulation and fault protection by supplementary insulation.
To connect the neutral (star) point of transformers and generators to Earth.
To ensure that electrical equipment can be dimensionally compatible with other systems.
According to section 412.1.2, where this protective measure is to be used as the sole protective measure, what should not be allowed?
Changes that could impair the effectiveness of the protective measure.
The use of a protective conductor contact.
The connection of the midpoint of the secondary windings of single-phase transformers to Earth.
The use of electrical equipment having basic insulation only.
Which regulations should electrical equipment comply with when having basic insulation only, as per section 412.2.1.2?
What symbol identifies electrical equipment that should have double or reinforced insulation (Class II equipment) according to section 412.2.1.1?
Where should the symbol indicating double or reinforced insulation be fixed, as mentioned in section 412.2.1.3?
On the interior of the enclosure only.
On the exterior of the enclosure only.
On both the exterior and interior of the enclosure.
On the protective conductor contact.
What should the insulating enclosure contain according to section 412.2.2.1?
All conductive parts separated from live parts by basic insulation
Only conductive parts that are necessary for operation
All mechanical joints and connections
Any replacement by metallic screws or other fixing means
According to section 412.2.2.2, what is required if the insulating enclosure must be traversed by mechanical joints or connections?
The connections should be insulated with a barrier
The connections should be arranged to not impair protection against shock in case of a fault
The connections should be marked as protective conductor (PE) terminals
The connections should be connected to a protective conductor
What is NOT allowed to be connected to a protective conductor as per section 412.2.2.4?
Conductive parts enclosed in the insulating enclosure
Conductive parts necessary for the operation of the equipment
Conductive parts that are marked as protective conductor (PE) terminals
Conductive parts that are not necessary to run through the enclosure
What is the minimum rated voltage of the cable(s) for wiring systems to meet the requirements of 412.2.4.1?
Less than the nominal voltage of the system
At least 300/500 V
Exactly 300/500 V
More than 500 V
What type of protective measure is described in section 413.1.1?
Protective bonding
Electrical separation
Automatic disconnection of supply
Double or reinforced insulation
According to the document, what is the maximum voltage allowed for the separated circuit in electrical separation to comply with Regulations 413.3.2 to 413.3.6?
1000 V
500 V
600 V
750 V
What must be visible throughout any part of their length liable to mechanical damage in flexible cables?
The color coding of the wires
The insulation resistance value
The basic insulation
The cable itself
What is required for protection by extra-low voltage provided by SELV or PELV?
Limitation of voltage to the upper limit of voltage Band 2
Protective separation of the SELV or PELV system from all circuits other than SELV and PELV circuits
No need for basic insulation between the SELV system and Earth
The use of SELV or PELV according to Section 414 is not considered a protective measure
What is the upper limit of voltage for SELV or PELV systems according to the document?
50 V AC or 120 V DC
100 V AC or 200 V DC
75 V AC or 150 V DC
60 V AC or 130 V DC
Is the use of SELV or PELV according to Section 414 considered a protective measure in all situations?
Yes
No
According to Regulation 414.2, protection for basic protection and fault protection is deemed to be provided where the nominal voltage does not exceed the upper limit of which voltage Band?
Band I
Band II
Band III
Band IV
As per Regulation 414.2, which of the following is NOT a requirement for basic protection and fault protection to be deemed provided?
The supply is from one of the sources listed in Regulation 414.3.
The conditions of Regulation 414.4 are fulfilled.
The system is supplied from a higher voltage system by equipment which provides at least simple separation.
The system is supplied from a low-voltage system that does not meet the requirements for SELV and PELV sources.
What is the maximum voltage for a DC system with batteries, where the battery charging and floating voltages exceed the battery nominal voltage, as specified in Regulation 414.2 NOTE 3?
75 V AC
120 V DC
150 V DC
50 V AC
Regulation 414.3 states that sources for SELV and PELV systems may include a safety isolating transformer in accordance with which BS EN standards?
BS EN 61558-2-6 or BS EN 61558-2-8
BS EN 61046-2
BS EN 61558-2-15
BS EN 61439-1
According to Regulation 414.4.1, SELV and PELV circuits shall have basic insulation between live parts and other SELV or PELV circuits, and what additional protection?
Protective separation from live parts of circuits not being SELV or PELV
Double or reinforced insulation or by basic insulation and protective screening for the highest voltage present
Connection to Earth or to an earthed protective conductor within the source itself
All of the above
According to Table 4.1.6, what is the maximum earth fault loop impedance (Zs) for a 5 disconnection time and Uo of 55 V for a circuit-breaker with a rating of 10 amperes to BS EN 60898 and the overcurrent characteristics of RCDs to BS EN 61009-1 Type B?
1.21 ohms
0.52 ohms
1.05 ohms
0.60 ohms
What is the maximum earth fault loop impedance (Zs) for a 5 disconnection time and Uo of 63.5 V for a general purpose (gG) fuse to BS 88:2 with a rating of 32 amperes?
0.38 ohms
0.16 ohms
0.48 ohms
0.95 ohms
Which of the following is a source of supply to a reduced low voltage circuit as per Regulation 411.8.4?
A double-wound isolating transformer complying with BS EN 61558-1 and BS EN 61558-2-23
A single-wound isolating transformer complying with BS EN 61558-1
A battery storage system
A photovoltaic power generator
What is the factor for correction of the circuit loop impedances given in the table, as noted in NOTE 1?
0.95
0.75
1.05
0.85
What is the purpose of double or reinforced insulation according to section 412.1.1?
To provide basic protection and fault protection by basic insulation and supplementary insulation, respectively.
To allow for dimensional compatibility with other systems.
To connect the neutral (star) point of transformers and generators to Earth.
To support the weight of luminaires and cable couplers.
Which of the following is NOT a requirement for circuits as per section 411.8.5?
Every plug, socket-outlet, and luminaire supporting coupler (LSC) should have a protective conductor contact.
Devices for connecting a luminaire (DCL) and cable coupler should not be dimensionally compatible with those used for any other system in the same premises.
The protective conductor contact should not be dimensionally compatible with those used for any other system in the same premises.
Low voltage systems should have a protective conductor contact.
According to section 412.2.1.3, what must electrical equipment with uninsulated live parts have?
Basic insulation only.
Reinforced insulation applied in the process of erecting the electrical installation.
A connection to Earth for the neutral (star) point of transformers and generators.
A protective conductor contact that is dimensionally compatible with other systems.
What symbol identifies electrical equipment that has double or reinforced insulation according to section 412.2.1.1?
A symbol referring to BS EN 60417: Class II equipment.
A symbol referring to BS EN 61439 series.
A symbol indicating supplementary insulation only.
A symbol indicating basic insulation only.
