Worksheets312 - Electrical supplies to the property
Total questions: 47
Worksheet time: 24mins
What is the role of a transformer in the electrical generation process?
To decrease the voltage
To increase the voltage
To convert AC to DC
To store electrical energy
what voltage does a transformer increase the electromotive force?
10,000 volts to 100,000 volts
22,000 volts to 400,000 volts
50,000 volts to 500,000 volts
30,000 volts to 300,000 volts
Why does electricity need to be transmitted at very high voltages?
To reduce power loss through power lines
To increase the speed of transmission
To decrease the cost of electricity
To improve the quality of electricity
What are the typical voltages of a supergrid ?
400kV and 275kV
132kV and 33kV
11kV and 400V
230V and 400V
What is the role of sub-stations in the National Grid?
They generate electricity.
They transform the electrical supply down to 11kV.
They increase the electrical supply to 400kV.
They store electricity for later use.
At what voltage is electricity finally distributed to customers?
11kV
132kV
400V
230kV
How is electricity distributed to customers after being transformed to 400V?
Through overhead power lines.
Via an underground supply.
By wireless transmission.
Through solar panels.
What voltage supply will enter a dwelling at the mains intake ?
110V
230V
240V
120V
What type of fuse is provided by the supplier?
Low breaking capacity (LBC) fuse
Medium breaking capacity (MBC) fuse
High breaking capacity (HBC) fuse
Standard fuse
What is the purpose of the sealed energy meter mentioned?
To regulate voltage
To measure consumption
To provide backup power
To control the current
What are the two conductors in the supply cable mentioned ?
Live and ground
Live and neutral
Neutral and earth
Phase and earth
What is the purpose of equipotential bonding arrangements in a system?
To increase voltage
To prevent electrical shock
To reduce current
To enhance conductivity
Where does the earth cable start in the supply to the property?
At the main earth terminal (MET)
At the consumer unit
At the supplier’s fuse
At the copper pipe
What does the main earth terminal (MET) connect to?
Only the consumer unit
Only the extraneous metal conductors
All components requiring an earth
Only the copper pipes
What is the primary purpose of the earth cable?
To provide a zero-volt path for fault current to flow to earth
To increase the voltage in a circuit
To act as a main power conductor
To disconnect the circuit during a fault
What is another term for the earth cable?
Protective conductor
Main conductor
Insulating wire
Voltage regulator
What does equipotential bonding ensure?
All metal parts are at the same potential or voltage
All circuits are disconnected
Voltage is increased in the system
Only one part is earthed
Why is it important for the consumer unit to have an earth?
So each circuit can have its own earth
To increase the current flow
To reduce the circuit's efficiency
To disconnect the circuit
In electrical terms, what is it called when a person is in contact with live exposed parts of an electrical system?
Indirect contact
Direct contact
Insulated contact
Grounded contact
What is the electrical term for contact of persons or livestock with exposed-conductive parts that have become live under fault conditions?
Direct contact
Indirect contact
Live contact
Fault contact
What does TN-S stand for in earthing systems?
Terra (earth) Neutral – Separate
Terra (earth) Neutral – Combined – Separate
Terra Terra
Terra (earth) Neutral – Combined
Which earthing system is represented by Terra Terra?
TN-S
TN-C-S
TT
TN-C
What is the significance of understanding earthing systems for a plumber?
It helps in designing water systems.
It indicates how the earth is connected and is important during testing and inspection of the circuit.
It is used for calculating water pressure.
It helps in choosing the right pipe material.
In a TN-S system, where does the earth start?
At the main switch
At the outer sheathing of the supply cable
At the gas meter
At the water service pipe
What is the size of the main earthing connection in a TN-S system as shown in the diagram?
16mm²
10mm²
20mm²
5mm²
In a TN-C-S system, where does the earth connection start?
At the consumer unit
At the incoming supplier’s fuse
At the main earth bar
At the copper cold water supply
What is required for a TT earthing arrangement?
A metal gas pipe
An earth rod
A water service pipe
A gas meter
What does CSA stand for in the context of cable sizing?
Cable Size Area
Cross-sectional Area
Conductor Size Area
Circuit Size Area
What is the minimum CSA for bonding conductor sizes on a TT system?
4mm²
5mm²
6mm²
7mm²
Where are three-phase supplies normally used?
Residential homes
Industrial and commercial properties
Small offices
Rural areas
What is the voltage step down from and to in a substation transformer for three-phase supplies?
11kV to 400V
10kV to 300V
12kV to 500V
9kV to 350V
What type of coils are used in a substation transformer for three-phase supplies?
Square and Circle
Delta and Star
Triangle and Hexagon
Circle and Square
What is the potential difference between any two of the three phases in a three-phase supply?
230V
400V
500V
600V
In which type of property is it unlikely for a domestic plumber to encounter a three-phase supply?
Commercial properties
Residential homes
Industrial buildings
Medical facilities
Who should be contacted to carry out three-phase electrical work?
A domestic plumber
A competent electrician
A construction worker
A building inspector
Which of the following is NOT a typical location for three-phase supplies?
Retail or office buildings
Factories or manufacturing plants
Residential homes
Hospitals
Why is it important to contact a competent electrician for three-phase electrical work?
It is extremely dangerous
It is very expensive
It is time-consuming
It is unnecessary
What is the voltage level of the substation transformer shown in the diagram?
11 kV/400 V
10 kV/500 V
12 kV/450 V
9 kV/350 V
Which phase is connected to the 400 V three-phase and neutral load in the diagram?
Brown phase
Black phase
Grey phase
Blue phase
What is the color code for the phase (live) wire in single-phase 230V installations?
Blue
Brown
Green
Yellow
In single-phase 230V installations, what color is used for the neutral wire?
Red
Black
Blue
Grey
What are the colors used for the earth wire in single-phase 230V installations?
Red and Yellow
Green and Yellow
Blue and Black
Brown and Grey
For three-phase 400V installations, what is the color code for L1?
Black
Grey
Brown
Blue
What was the color code for the live wire in single-phase installations before 2004?
Blue
Red
Brown
Black
In three-phase installations before 2004, what color was used for L2?
Yellow
Blue
Red
Brown
What year did the harmonisation of cable colour codes occur?
2004
1999
2010
1995
What is the purpose of the warning label in the diagram?
To alert about different colour codes
To indicate voltage levels
To show installation date
To provide safety instructions
