Worksheets312 - Electrical circuits and components
Total questions: 52
Worksheet time: 26mins
What are the typical electrical circuits found in a modern dwelling?
Ring main, Lighting, Power circuit (radial)
Solar panel, Wind turbine, Battery storage
Generator, Transformer, Inverter
Circuit breaker, Fuse, Resistor
How many ring mains are typically found in a modern dwelling?
1
2
3
4
Where are the lighting circuits typically located in a modern dwelling?
Both upstairs and downstairs
Only in the kitchen
Only in the living room
Only in the basement
What might the power circuits in a modern dwelling be used for?
Cooker, central heating, and alarm
Television, radio, and computer
Refrigerator, microwave, and dishwasher
Washing machine, dryer, and vacuum cleaner
What do consumer units house for radial and ring final circuits?
Individual MCBs
Circuit breakers
Fuses
Transformers
What is incorporated in consumer units to provide protection against earth leakage?
RCD
Fuse
Circuit breaker
Transformer
As of 2019, what material must all newly installed consumer units be made of?
Metallic
Plastic
Wood
Ceramic
What protects the consumer unit in a circuit protective device setup?
Single pole isolator
Double pole main isolator
Circuit breaker
Fuse
How are the MCBs split in the circuit protective device setup?
In a single bank
In three banks
In two banks
Randomly
What does each bank of MCBs have for protection?
Its own fuse
Its own RCD
Its own circuit breaker
Its own isolator
What types of circuits do the MCBs protect?
Only lighting circuits
Only power circuits
Ring final circuits, lights, and power circuits
Only ring final circuits
What does an RCBO combine the functions of?
An MCB and a fuse
An RCD and a fuse
An MCB and an RCD
A circuit breaker and an isolator
What is the purpose of the earth bar in a consumer unit?
To connect the live wires
To provide a path to ground for electrical safety
To distribute the neutral current
To control the circuit breakers
Which component in a consumer unit is responsible for distributing the incoming live current?
Neutral bar
Earth bar
Live in
Busbar
In a consumer unit, what is the function of the busbar?
To connect the earth wires
To distribute electrical power to circuit breakers
To measure electrical current
To provide a neutral connection
What is the primary function of circuit protective devices like MCBs?
To increase the voltage in a circuit
To permanently isolate circuits in an over-current situation
To decrease the current in a circuit
To provide power to the circuit
What does MCB stand for?
Main Circuit Board
Miniature Circuit Breaker
Maximum Current Breaker
Main Current Blocker
What is a typical use for a 6A MCB?
Heating circuits
Lighting circuits
Motor circuits
Cooling circuits
What is the maximum operating current for a residual current device (RCD)?
10mA
20mA
30mA
40mA
What happens when an RCD detects an imbalance in the circuit?
The circuit continues to operate normally.
The circuit is automatically disconnected.
The current is increased.
The voltage is reduced.
How quickly should an RCD disconnect to protect a 32A circuit?
0.2s
0.4s
0.6s
0.8s
What is the role of an RCD in the event of failure of basic protection?
It provides additional protection.
It reduces the voltage.
It increases the current.
It disconnects the power supply permanently.
What is the function of the fuse in older fuse boards?
To create the circuit from the copper busbar to the individual circuit
To provide power to the entire building
To regulate the voltage in the circuit
To act as a backup power source
Where are the fuses inserted in older fuse boards?
Into the slots on an exposed busbar
Directly into the power outlet
Into a separate fuse box
Into the main power switch
What is a characteristic of a cartridge fuse to BS 1361?
It is cheaper than semi-enclosed fuses.
It is fitted into a consumer unit like a rewireable fuse.
It cannot be replaced incorrectly.
It is used only in industrial settings.
What is a disadvantage of cartridge fuses compared to semi-enclosed fuses?
They are less reliable.
They are more expensive.
They are harder to install.
They have a lower current rating.
What does the wire diameter in a semi-enclosed fuse to BS 3036 relate to?
The voltage rating.
The physical size of the fuse.
The current rating.
The temperature rating.
What type of cables are generally flat PVC two-core and earth, depending on the circuit they feed?
Flex cables
Multicore flex
Singles cables
Consumer unit cables
Where are flex cables often found?
In consumer units
On individual appliances
In boiler controls
In gas solenoids
What is a possible use for multicore flex cables?
Connecting a gas solenoid
Wiring boiler or heating controls
Feeding consumer units
Protecting with a conduit
What type of cables may be used with mechanical protection such as a conduit?
Flex cables
Multicore flex
Singles cables
PVC two-core cables
What is the typical use of flex cables?
For underground wiring
For extension cables and leads for appliances above floor level
For outdoor lighting
For automotive wiring
Why is the correct selection of flex important?
To reduce cost
To prevent overheating
To improve signal quality
To increase flexibility
What is the wattage capacity for a 1.0mm cable ?
700w
1400w
2400w
3600w
Which appliance is suitable for a 0.75mm cable?
Lights
Central heating
Kettle/immersion
Commercial
What is the primary use of armoured cable?
To connect household appliances
To supply an incoming mains or outhouse with power
For internal wiring in homes
To connect to portable devices
What additional feature does the metal armour of the cable provide?
Electrical insulation
Aesthetic appeal
Mechanical protection
Heat resistance
What type of appliances use heat-resistant flex?
Refrigerators
Kettles
Televisions
Computers
What is the typical power rating for an immersion heater that uses heat-resistant flex?
1.0–1.5kW
2.5–3.0kW
3.5–4.0kW
4.5–5.0kW
What is the maximum temperature that heat-resistant flex can withstand without damage?
65°C
75°C
85°C
95°C
What is the typical capacity in amps for a 1.5mm twin and earth (CPC) cable?
11A
14A
18A
25A
Which domestic usage is a 6.0mm twin and earth (CPC) cable typically used for?
Lighting
Sockets
Shower
Cooker
What is the fuse rating range for a 2.5mm twin and earth (CPC) cable?
6-10 amps
16-20 amps
30-32 amps
45 amps
According to the table, which cable size is used for cookers?
1.0mm
2.5mm
6.0mm
10mm
What is the primary use of back boxes (pattress boxes) and joint boxes in electrical installations?
To decorate walls
To fix fascias or outlets and securely join cables
To increase electrical current
To reduce noise
Which of the following is an example of a back box?
Galvanised steel single recessed back box
Wooden frame box
Metal conduit box
Plastic cable tie
What material is used for a plastic surface mounted single back box?
Wood
Metal
Plastic
Glass
Which type of box is used for heating control installations?
Galvanised steel single recessed back box
Wiring centre box
Plastic surface mounted jointing boxes
Bakerlite plastic jointing boxes
What is the purpose of fascias in electrical installations?
To provide lighting
To serve as a switch plate or outlet
To generate electricity
To cool down electrical devices
Which of the following is a type of fascia with a neon indicator?
Plastic fan isolator switch
Pull cord switch for shower
Plastic unswitched fused spur
Brushed steel single switched socket outlet
Identify the fascia type used for controlling a shower.
Plastic switched fused spur
Pull cord switch
Cooker switch with socket outlet
Brushed steel single switched socket outlet
What is the purpose of using adapters in electrical fittings?
To enhance the aesthetic appearance of cables
To ensure a secure connection and prevent disconnection or abrasion
To increase the length of the cables
To reduce the electrical resistance of the cables
