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WorksheetsEAL ELEC3/04a: Planning/preparing/designing - OSG required
Total questions: 99
Worksheet time: 51mins
Which of the following statutory requirements is most important when planning an installation?
Health and Safety Act 1974
BS 7671 Wiring Regulations
Building Regulation 2000
Electricity at Work Regulation 1989
Which of the following is an important consideration regarding the movement of vehicles and adequate flood lighting?
safe access and egress
training facilities
adequate welfare facilities
a safety policy
According to the Electricity at Work Act 1989 when can you carry out a ‘live’ repair?
only if you are supervised
only if you feel that you are ‘competent’ to do so
never, you are not allowed to
only if you are experienced
As fitted, drawings form part of the:
fitting element
timetabling element
scheduling element
completion element
Band 1 and Band 2 cabling can be enclosed in the same enclosure if:
they are insulated to the highest voltage present
at 90° to each other
separated by metal divisions
wrapped around each other
What kind of drawing is this?
block
schematic
detail
layout
Which document details the duties of employers to employees in providing a safe place of work?
IET Wiring Regulations
Building Regulations
Electricity at Work Regulations
Health and Safety at Work Act.
Ignoring BS 7671 would most likely cause:
an electrical fire
a real fire
a solid fuel fire
a gas fire.
Removing all elements of electrical supply to a piece of equipment in order to ensure the safety of those working on it is one definition of:
emergency switching
functional switching
safe isolation
switching for mechanical maintenance.
Cutting off the full load electrical supply to a piece of equipment in order to ensure the safety of those working on it is one definition of:
emergency switching
functional switching
switching for isolation
switching for mechanical maintenance.
The rapid disconnection of the electrical supply to remove or prevent danger is one definition of:
emergency switching
functional switching
switching for isolation
switching for mechanical maintenance.
Switching electrical equipment in normal service is:
emergency switching
functional switching
switching for isolation
switching for mechanical maintenance.
Looking at the diagram, the numbers 2, 3 and 4 represent:
service meter, meter tails, service fuse
service head, meter tails, service fuse
service head, service meter, service fuse.
The maximum working temperature of PVC/PVC thermoplastic is:
40°C
50°C
60°C
70°C.
A light fitting or small spot light must be fixed at an adequate distance from:
combustible material
combustible walls
combustible ceilings
combustible joists.
Which of the following CANNOT be used as an isolator?
switch
circuit-breaker
semi-conductor (electronic device)
switch disconnector.
What equipment type does this symbol relate to:
Class I
Class II
Class III
Class IV.
Three factors that would affect the choice of wiring system would include:
temperature
animals and plants
architect
impact damage
Additional protection applies to:
cables located within metal enclosures
SWA
cables embedded >50 mm
cables embedded <50 mm
special locations
What is the normal size and rating of a lighting cable and protective device?
6 mm² and 6 A
2.5 mm² and 6 A
4 mm² and 6 A
1.5 mm² and 6 A
Equipment installed in a flour mill needs to be protected against entry of particles such as:
dust stopped through IP protection
dust stopped through fault protection
dust stopped through basic protection
dust stopped through additional protection
The protection provided by insulating live parts is called:
extraneous conductive parts
basic protection
exposed conductive parts
fault protection
The typical cabling for use in electrical installations in domestic premises would be:
SWA
PVC/PVC
MICC
PVC single
Ladder racking is a system for:
allowing access to storage racks
allowing multiple section extension ladders
supporting armoured cables
supporting vertical cable basket systems
The type of wiring for use in a factory with high ambient temperatures is:
PVC insulated and sheathed
PVC insulated cables in galvanized conduit
mineral insulated metal sheathed
rubber insulated in PVC conduit
Mineral insulated cables are sometimes provided with an overall covering of PVC to:
make the cable waterproof
protect the cable from sunlight and harmful rays
prevent corrosion of the sheath
make the cable suitable for use in low ambient temperatures
Where would it be unsuitable to use a rate of rise temperature type heat detector?
kitchen
dining room
hallway
garage
An appropriate wiring method for an underground feed to a remote building would be a:
metal conduit installation
trunking and tray installation
PVC cables
PVC/SWA cables
An appropriate wiring system for a three-phase industrial installation would be:
PVC cables
PVC conduit
one that meets the requirements of Part 2 of the IET Regulations
one that meets the requirements of Part 5 of the IET Regulations
Which wiring system is non-ageing and will ensure that the space between its conductors is kept the same even if flattened?
mineral insulated
SWA
PVC/PVC
PVC singles
Which conductor uses the principle of total internal refraction?
FP cable
fibre-optic
mineral insulated
PVC/PVC flat profile cable
An alternative to mineral insulated cable that does not require specialized tools would be:
FP
fibre-optic
SWA
PVC flex
Which of the following is the most appropriate containment system for industrial high current applications?
busbar systems
flexible conduit
cable tray
power track
Which of the following would be most appropriate regarding offsetting the adverse effects of vibration?
PVC conduit
plastic conduit
metal conduit
flexible conduit
Which of the following apply to electrical equipment in bathrooms?
supplementary bonding
index protection
earthing
additional protection
The maximum floor area that a ring circuit can feed is:
50 m²
75 m²
100 m²
25 m²
Combining a copper cable with an aluminium crimp will result in:
increased fault current
lower termination resistance
dissimilar metal corrosion
an explosion
Single core non-armoured cables (apart from bonding conductors) must always be installed:
in free air partially covered
in conduit or trunking
secured with plastic clips
in cavity walls
A non-fused spur from a ring may feed:
any number of socket outlets
any number of fixed appliances
one single or twin socket outlet
two fixed appliances
An A1 type circuit is associated with:
2.5 mm with 30/32 A fuse
4 mm radial with protective device
1.5 mm radial with 20 A fuse
4 mm ring with 20 A fuse
Ten 1.0 mm single conductors are to be drawn into a conduit. Use Table E3 of the On-Site Guide to find the sum of the cable factors for these cables.
16
30
160
300
A three-metre length of conduit with two bends is to contain the ten 1.0 mm cables. Determine the size of conduit required using Table E4 of the On-Site Guide.
16 mm
20 mm
25 mm
32 mm
Ten 2.5 mm single conductors are to be drawn into a conduit. Use Table E3 of the On-Site Guide to find the sum of the cable factors for these cables.
16
30
160
300
A three-metre length of conduit with two bends is to contain the ten 2.5 mm cables. Determine the size of conduit required using Table E4 of the On-Site Guide.
16 mm
20 mm
25 mm
32 mm
Ten 1.5 mm solid PVC cables are to be drawn into trunking. Use Table E5 in the On-Site Guide find the sum of the cable factors for these cables.
80
60
40
20
Ten 2.5 mm solid PVC cables are to be drawn into trunking. Use Table E5 in the On-Site Guide to find the sum of the cable factors for these cables.
116
117
118
119
Refer to Tables E1 and E2 of the On-Site Guide and by applying cable and conduit factors, work out how many 4 mm² cables can be inserted into a 25 mm piece of conduit used in a short straight run.
14
13
12
11
Additional protection is applicable to which of the following?
HRC fuse
re-wireable fuse
RCBO
CB
Which of the following will not operate if the line conductor bypasses the load and shorts out against the neutral conductor?
HRC fuse
RCD
RCBO
CB
An Industrial welder would need to be protected by:
an RCD
a Type C circuit-breaker
a Type D circuit-breaker
a HBC fuse
Coordination of fuses during fault or overload conditions is known as:
diversity
diverging
discrimination
deviation
A circuit-breaker has two modes of operation:
overload due to thermal effect or short circuit due to a magnetic trip
overload due to a magnetic trip or short circuit due to thermal effect
overload due to a chemical reaction or short circuit due to a magnetic trip
overload due to a thermal trip or chemical reaction due to a magnetic trip.
A CB rated at 40 A will trip:
only when a short circuit occurs
only when an overload occurs
when an overload, short circuit or earth fault occurs
when 41 A flows through it.
An RCD rated at 30 mA will trip:
when enough current flows to earth
through an earth fault or an overload
through an overload, short circuit or earth fault
when 30 mA flows.
What type of CB is associated with commercial applications especially fluorescent lighting?
Type 3
Type B
Type C
Type D
Which device will detect an imbalance between line and neutral, overloads and all types of overcurrent faults?
RCD
RCBO
CB
BBC
A fuse protects:
the person
the switch
the cable
the load
An RCD protects:
the person
the switch
the cable
the load
A value that ensures that a circuit-breaker can withstand a fault current is known as:
breaking capacity
rating
thermal constraint
shock protection
Which earthing system is not recommended for petrol stations, caravans and marina pontoons?
TN-S
TT
TNC
PME
What is the maximum tabulated value of Zₑ for a TN-C-S system?
(a)
Which earthing system due to the possibility of high Zₑ values must have additional protection?
TN-S
TT
TN-C-S
PME
Which uncommon earthing system is used in hospitals?
TN-S
IT
TNC
PME
What supply system uses a PEN conductor?
TT
TN-S
IT
TN-C-S
Which earthing system uses an earth electrode and is common in rural areas?
TN-S
TT
TN-C-S
PME
The metalwork that does not form part of an electrical installation is called:
extraneous conductive parts
basic protection
exposed conductive parts
fault protection
Which of the following is an extraneous conductive part?
metal casing of a washing machine
metal switch back plate
metal casing of an electric motor
metal casing of a gas pipe
A current that goes beyond the rated value in an otherwise healthy circuit is one definition of:
earthing
bonding
overload
short circuit
What is the maximum disconnection time for TT earthing systems > 32 A?
5 s
1 s
0.2 s
0.4 s
A TN-S earthing system operates through the:
earthing electrode
PEN conductor
supply cable armouring
earth itself
Earthing ensures that:
a low resistance path, will safeguard that the PFC is high and ensure disconnection is quick
a high resistance path, will safeguard that the PFC is high and ensure disconnection is quick
a low resistance path, will safeguard that the PFC is low and ensure disconnection is slow
a high resistance path, will safeguard that the PFC is low and ensure disconnection is quick
Which of the following symbols represents the external earth loop impedance value?
Zx
Zs
Ze
ZT
Which of the following symbols represents the total earth loop impedance value?
Zx
Zs
Ze
ZT
The protection provided by equipotential bonding and automatic disconnection of the supply is called:
extraneous conductive parts
basic protection
exposed conductive parts
fault protection
Equipotential bonding is carried out to:
earth all equipment
earth all exposed conductive parts
link all extraneous conductive parts
stop fuses operating
Which earthing system changes line to earth faults to line to neutral faults?
TN-S
TT
TN-C-S
IT
A TN-S earthing system will follow which path?
CPC, main earthing terminal, supply armouring back to the transformer
earth electrode, CPC, main earthing terminal back to the transformer
main earthing terminal, CPC, PEN conductor, back to the transformer
CPC, high impedance load, main earthing terminal back to the transformer.
Which earthing system has to be earthed itself along its various supply routes?
TN-S
TT
PME
IT
What device is described here: The ‘It’ rating must be equal to or above the normal operating current of the circuit?
a. a fuse
b. fuse-board
c. distribution board
d. junction box
What device is described here: The ‘It’ rating must be equal to or above the normal current carrying capacity of the protective device?
a. cable
b. switch
c. load
d. consumer unit
Calculate the total current demand for a domestic lighting circuit if it contains 20 × 100 W GLS filaments and the factor for diversity is 66%.
a. 7.8 A
b. 8.69 A
c. 6 A
d. 5.7 A
When cabling is routed through insulation, the rated:
a. current carrying ability will be decreased
b. current carrying ability will be increased
c. current carrying ability will stay exactly the same
d. current carrying ability will be doubled per metre
If voltage drop in a final circuit is found to be excessive the corrective action is to:
a. limit the time the load is connected
b. boost the voltage through a transformer
c. increase the size of the supply cable
d. decrease the size of the supply cable
Which of the following is correct regarding earth fault loop impedance?
a. Zs can be obtained by enquiry
b. Ze can be obtained by enquiry
c. Zs can be obtained by calculation
d. Zs can be obtained by measurement
One disadvantage of using the tabulated values of Ze in the On-Site Guide is:
they are hard to read
the values could be high
the values are unreliable
the values could be low
When checking earth loop impedance values which of the following can be used directly without correction?
BS 7671
wiring regulations
GN3
On-Site Guide
A domestic cooker rated at a maximum load of 60 A is controlled by a cooker control unit, which does not have a 13 A socket outlet. Using Table A1 of the On-Site Guide, and after allowing for diversity, calculate the design current.
20 A
25 A
18 A
30 A
Correction factors as applied to de-rate system cables are:
thermal insulation, grouping, re-wireable fuses and ambient temperature
outside insulation, grouping, re-wireable fuses and ambient temperature
using SWA cable, grouping, re-wireable fuses and ambient temperature
thermal insulation, bare wires, re-wireable fuses and ambient temperature
Which of the following should be recorded regarding the PFC?
the prospective short circuit current
the prospective earth fault current
the highest value PFC at the point of supply
the higher value PFC at the furthermost point of the circuit
Why is thermal constraint particularly important when installing with PVC flat profile cable?
it is cheap in comparison to other types
its CPC is smaller than the live conductors
its CPC is bigger than the live conductors
its CPC does not come with earthing sleeving
To ensure the effective operation of the overcurrent protective devices, the earth fault loop path must have:
a 230 V supply
very low resistance
fuses or CBs in the live conductor
very high resistance
Shock protection ensures that:
a. the protective device operates within a specified time
b. the actual loop impedance values are less than specified
c. the PFC is low enough to operate the protective devices in time
d. the circuit is switched off in time.
According to IET Regulation 411.3.2.2 all final circuits not exceeding 32 A in a building supplied with a 230 V TN supply shall have a maximum disconnection time not exceeding:
a. 0.2 s
b. 0.4 s
c. 5.0 s
d. unlimited.
The current demand of ten 65W fluorescent tubes connected to a 230 V supply is:
a. 5.08 mA
b. 5.09 A
c. 150 W
d. 650 W.
Use the On-Site Guide (Appendix A) to calculate the assumed current demand of a cooker having 4–3 kW boiling rings and a 2 kW oven connected to a 230 V supply. The cooker control unit includes a socket outlet.
a. 60.86 A
b. 30.26 A
c. 25.25 A
d. 10 A.
The total current demand of a lighting circuit in an individual household is calculated to be 5 A. The current demand applying the diversity factor given in Table A2 of the On-Site Guide will be:
a. 3.3 A
b. 3.75 A
c. 4.5 A
d. 5.0 A
The volt drop in mV per ampere per metre of a two-core single-phase 6.0 mm cable as given in Table F5 (ii) of the On-Site Guide is:
a. 18
b. 11
c. 7.3
d. 4.4.
The volt drop in mV per ampere per metre of a two-core single-phase 10.0 mm cable as given in Table F5 (ii) of the On-Site Guide or Table 3.13 of this book is:
a. 18
b. 11
c. 7.3
d. 4.4.
With respect to the volt drop values, which of the following applies?
volt drop value is less if cable size is increased
volt drop value is bigger if cable size is increased
volt drop value is less if cable size is decreased
volt drop value is less if cable size is bigger
