Electrical safety

Following some construction work in a house, an exposed live wire with no insulation is sticking out from a wall. What is the greatest hazard?

Feb/March 2016

Following some renovation work in a house, a live wire without insulation is left sticking out of a wall. What is the biggest danger?

Feb/March 2016

In this circuit, a component at X automatically prevents the wiring from overheating if a fault develops. Which row shows the components that are suitable?

Feb/March 2017

In this circuit, a component at X gives automatic protection to the wiring against overheating when a fault occurs. Which row shows components that are suitable?

Feb/March 2017

A kettle carries a current of $10\,\text{A}$ and is safeguarded by a $13\,\text{A}$ fuse. The kettle’s owner changes the $13\,\text{A}$ fuse for a $3\,\text{A}$ fuse. What will occur when the kettle is switched on?

Feb/March 2019

An appliance circuit contains a $5\,\text{A}$ fuse. What is the function of the fuse, and in which wire is it connected?

Feb/March 2020

Which electrical component is placed in series with an electric circuit to prevent damage from a very large current?

Feb/March 2021

A student is using a laptop computer. The student sees that the cable linking the laptop power adapter to the mains electricity supply is damaged, as shown in Fig. 10.1.

Feb/March 2021

A man crosses a carpet. By friction with the carpet, he becomes negatively charged. What occurs when he touches a metal object that is connected to the Earth?

Feb/March 2023

The current in a kettle is 10\,A, and a 13\,A fuse protects the kettle. The kettle owner changes the 13\,A fuse to a 3\,A fuse. What occurs when the kettle is switched on?

Feb/March 2023

To switch a mains appliance on and off safely, into which wire should a switch be connected?

Feb/March 2024

A domestic circuit has a $30\,\text{A}$ fuse fitted. It safeguards the wiring when the current in the circuit becomes too large. In which wire is the $30\,\text{A}$ fuse placed, and what happens to it when it operates?

May/June 2016

A domestic circuit has a $30\,\text{A}$ fuse. It safeguards the wiring when the current in the circuit becomes too large. In which wire is the $30\,\text{A}$ fuse fitted, and what happens when it functions?

May/June 2016

A rod carrying negative charge is brought near one side of a metal sphere. The opposite side of the sphere is connected to earth. Which diagram shows how charge is distributed on the metal sphere?

May/June 2016

A domestic circuit contains a $30\,\text{A}$ fuse. This protects the wiring if the current in the circuit becomes too large. Which wire is the $30\,\text{A}$ fuse fitted into, and what happens when it blows?

May/June 2016

A domestic circuit is fitted with a $30\,\text{A}$ fuse. It safeguards the wiring when the current in the circuit becomes too large. In which wire is the $30\,\text{A}$ fuse placed, and what happens when it works?

May/June 2016

A domestic circuit has a 30 A fuse. It safeguards the wiring when the current in the circuit becomes too large. In which wire is the 30 A fuse placed, and what happens when it blows?

May/June 2016

A circuit-breaker is intended to protect a circuit that normally carries a current of $2\,\text{A}$. The length of time needed to break the circuit varies with the current, as the graph shows. What occurs when the current in the circuit is $2\,\text{A}$ and what occurs when the current is $18\,\text{A}$?

May/June 2017

An electric heater is connected to the mains supply by means of a fused plug. The current in the heater is $10\,\text{A}$. The cable fitted to the heater is rated at $15\,\text{A}$. The fuses that can be chosen are rated at $1\,\text{A}$, $3\,\text{A}$, $5\,\text{A}$ and $13\,\text{A}$. Which fuse should be chosen?

May/June 2019

Which components are intended to improve the safe operation of a mains electrical supply?

May/June 2019

A basic wiring diagram for an electric cooker is shown. Why is there a wire that connects the cooker’s metal case to earth?

May/June 2019

An electric heater is connected to the mains supply by means of a fused plug. The current in the heater is $10\ \text{A}$. The cable fitted to the heater is rated at $15\ \text{A}$. The fuses available have ratings of $1\ \text{A}$, $3\ \text{A}$, $5\ \text{A}$ and $13\ \text{A}$. Which fuse is the correct choice?

May/June 2019

Which components are intended to improve the safe operation of a mains electrical supply?

May/June 2019

A basic circuit diagram for an electric cooker is shown. Why is a wire used to connect the cooker’s metal casing to earth?

May/June 2019

Fig. 10.1 depicts a desktop computer linked to the mains supply through a plug that contains a fuse.

May/June 2019

What is the purpose of a fuse in an electrical circuit?

May/June 2022

What is the purpose of a fuse in an electrical circuit?

May/June 2022

What is the purpose of a fuse in an electrical circuit?

May/June 2022

A microwave oven is built with a metal case and runs from a 240 V electricity supply.

May/June 2022

Fig. 5.1 depicts a kitchen tap that delivers instant boiling water. Cold water flows across an electric immersion heater inside the tap. Water boils at $100\,^{\circ}\text{C}$.

May/June 2022

A double-insulated electrical appliance has to be connected to the electricity supply in a safe way. Which statement is correct?

May/June 2023

Which of the following statements about electrical safety is correct?

May/June 2023

An electric heater has a metal frame. The heating element is linked to the live and neutral wires of an a.c. supply, while the metal frame is connected to the earth wire. Which row shows the correct arrangement for the fuse and the switch?

May/June 2023

The metal casing of an electrical appliance is connected to earth. What is the reason for this?

May/June 2024

In a mains electric circuit, where should a fuse be connected?

May/June 2024

Four statements concerning safety in the design of electrical products are given. Which ones are correct?

May/June 2024

Two electrical appliances are linked to the mains supply. The cable for one appliance has an earth wire included. The cable for the other appliance does not require an earth wire.

May/June 2024

State the fault in Fig. 9.1 and describe the hazard it shows.

May/June 2024

A mains-operated radio is a double-insulated appliance. Which statement is true?

May/June 2025

A vacuum cleaner powered from the $240\,\text{V}$ mains has an output power of $2700\,\text{W}$. Which fuse would be appropriate in the plug of the vacuum cleaner?

May/June 2025

A $240\,\text{V}$ vacuum cleaner operated from the mains has a power output of $2700\,\text{W}$. Which fuse would be suitable for fitting in the plug of the vacuum cleaner?

May/June 2025

In which mains electric wires are the fuse and the switch fitted?

May/June 2025

Fig. 8.1 shows an electric fan heater on a bathroom wall, powered from the mains.

May/June 2025

Suggest why a pull cord is safer than a push switch for use with a fan heater in a bathroom.

May/June 2025

Two electrical appliances are linked to the mains supply. The lead attached to one appliance contains an earth wire. The cable connected to the other appliance does not require an earth wire. What is one reason for this difference?

Oct/Nov 2016

An electric kettle has a metal outer casing. The kettle’s cable includes a wire linked to the earth pin of the plug. Which hazard does this protect against?

Oct/Nov 2016

A washing machine that is electrically powered is safeguarded by an earth wire. Which section of the washing machine should this earth wire be attached to?

Oct/Nov 2016

What is the purpose of a fuse in an electrical circuit?

Oct/Nov 2016

For what reason is a fuse used in an electrical circuit?

Oct/Nov 2016

An electric kettle is enclosed in a metal outer case. Its cable includes a wire linked to the earth pin of the plug. What danger is this intended to prevent?

Oct/Nov 2016

Two electrical appliances are linked to the mains supply. The lead attached to one appliance contains an earth wire. The lead attached to the second appliance does not require an earth wire. What is one reason for this difference?

Oct/Nov 2016

Fig. 9.1 illustrates the electric circuit used for a fan heater. Air is forced past the heater by the fan. A motor, which is connected to a 24 V d.c. supply, drives the fan.

Oct/Nov 2016

Fig. 9.1 shows a gardener mowing wet grass with a powerful electric mower.

Oct/Nov 2016

An appliance is connected to a mains supply. The circuit also has a switch and a fuse. Which circuit diagram shows the fuse in the correct location?

Oct/Nov 2017

An appliance is linked to a mains supply. Its circuit also includes a switch and a fuse. Which circuit shows the fuse placed in the correct position?

Oct/Nov 2017

An appliance is connected to the mains supply, and the circuit also includes a switch and a fuse. Which circuit shows the fuse placed in the correct position?

Oct/Nov 2017

A fuse or a circuit-breaker may be used to protect electrical cables from large currents that could lead to overheating. If a fuse is fitted, where should it be placed, and if a circuit-breaker is fitted, where should it be placed?

Oct/Nov 2018

A fuse or a circuit-breaker may be used to protect electrical cables against large currents that might make them overheat. If a fuse is fitted, at what point should it be connected, and if a circuit-breaker is fitted, at what point should it be connected?

Oct/Nov 2018

A fuse or a circuit-breaker may be used to protect electrical cables against large currents that could lead to overheating. If a fuse is used, where should it be placed, and if a circuit-breaker is used, where should it be placed?

Oct/Nov 2018

A fuse or a circuit-breaker may be used to protect electrical cables from large currents that could lead to overheating. If a fuse is used, where should it be placed, and if a circuit-breaker is used, where should it be placed?

Oct/Nov 2018

A fuse or a circuit-breaker may be used to protect electrical cables from large currents that could lead to overheating. If a fuse is used, at what point should it be connected, and if a circuit-breaker is used, at what point should it be connected?

Oct/Nov 2018

A fuse or a circuit-breaker may be used to protect electrical cables against large currents that might lead to overheating. If a fuse is used, where should it be placed, and if a circuit-breaker is used, where should it be placed?

Oct/Nov 2018

At what position should a fuse be connected in a mains electric circuit?

Oct/Nov 2019

At what point must a fuse be connected in a mains electric circuit?

Oct/Nov 2019

In a mains electric circuit, where should a fuse be connected?

Oct/Nov 2019

In a mains electric circuit, where should a fuse be placed?

Oct/Nov 2019

At what point should a fuse be placed in a mains electrical circuit?

Oct/Nov 2019

In a mains electric circuit, where should a fuse be connected?

Oct/Nov 2019

An electrical appliance runs from a mains supply. During normal operation, the appliance takes a current of $3\,\text{A}$, although this current momentarily increases to $4\,\text{A}$ when the appliance is first switched on. The cable connected to the appliance is made to handle currents of up to $6\,\text{A}$. A fuse is fitted to protect the circuit. What rating should the fuse have?

Oct/Nov 2020

An electrical appliance is supplied by a mains supply. The appliance usually draws a current of $3\,\text{A}$, although this current momentarily increases to $4\,\text{A}$ when the appliance is turned on. The cable connected to the appliance is intended to carry currents up to $6\,\text{A}$. A fuse is fitted to protect the circuit. What rating should the fuse have?

Oct/Nov 2020

An electrical appliance is supplied by a mains supply. During normal operation, the appliance takes a current of $3\ \text{A}$, although at the moment it is switched on the current momentarily increases to $4\ \text{A}$. The cable connected to the appliance is intended to carry currents up to $6\ \text{A}$. A fuse is fitted to protect the circuit. What should the fuse rating be?

Oct/Nov 2020

Fig. 10.1 depicts a metal kettle being used to heat water. It is plugged into the mains power supply, and its metal casing is earthed. A defect makes the live wire come free and touch the metal case, as shown.

Oct/Nov 2020

State and explain why electrical sockets and plugs used outside in a garden have to be different from those that can be used safely in a room inside a house.

Oct/Nov 2020

Which circuit includes a fuse?

Oct/Nov 2021

The metal casings of electrical appliances are linked to an earth wire. Which statement is not correct?

Oct/Nov 2021

A teacher asks, ‘Why is a fuse included in a mains circuit?’ Student 1 replies, ‘It stops the wiring from becoming too hot.’ Student 2 replies, ‘It stops us receiving an electric shock if we touch the live wire.’ Which student is correct?

Oct/Nov 2021

The current in a small electric heater is $4.0\,\text{A}$. The cable attached to the heater can carry currents of up to $10\,\text{A}$. Fuses with ratings of $1\,\text{A}$, $3\,\text{A}$, $5\,\text{A}$ and $13\,\text{A}$ are available. Which fuse should be chosen?

Oct/Nov 2021

In which circuit is a fuse included?

Oct/Nov 2021

The diagram illustrates a motor attached to an a.c. supply. The circuit is not complete. Which device must be placed between point X and point Y so that the wires do not overheat if a fault in the motor makes the current become too large?

Oct/Nov 2021

A hairdresser is using a hairdryer that has a plastic casing. He notices that no wire is connected to the plug’s earth pin. Why is an earth connection not required?

Oct/Nov 2021

An electric drill that runs from a supply voltage of $240\ \text{V}$ draws a current of $3.5\ \text{A}$. Which fuse rating should be selected to protect the drill cable?

Oct/Nov 2021

In which circuit is a fuse included?

Oct/Nov 2021

Circuit breakers and fuses are protective devices that prevent a circuit from becoming overloaded. Which statement correctly explains how a circuit breaker differs from a fuse?

Oct/Nov 2021

Why could using an electrical appliance in damp conditions be dangerous?

Oct/Nov 2021

The metal outer casings of electrical appliances are linked to an earth wire. Which statement is incorrect?

Oct/Nov 2021

The diagram illustrates a motor linked to an a.c. supply. The circuit is not complete. Which device should be placed between point X and point Y so that the wires do not overheat if a fault in the motor makes the current become too large?

Oct/Nov 2021

Circuit breakers and fuses are devices that protect a circuit against overloading. Which statement describes the difference between a circuit breaker and a fuse correctly?

Oct/Nov 2021

Name the logic gate that appears in Fig. 10.1.

Oct/Nov 2021

What is the purpose of a fuse in an electric circuit?

Oct/Nov 2022

If the insulation in a mains cable is damaged, two of the wires inside it may come into contact and create a short circuit. Which row is correct?

Oct/Nov 2022

A fuse is included in the circuit that connects a room heater to the mains electricity supply. As the fuse melts, it disconnects the circuit. Why does the fuse wire melt?

Oct/Nov 2022

Fig. 9.1 illustrates an unsafe situation involving the use of electricity in a kitchen.

Oct/Nov 2022

An electric heater is connected to the mains supply by means of a fused plug. The current in the heater is $10\,\text{A}$. The cable fitted to the heater has a rating of $15\,\text{A}$. The fuses that can be chosen are rated at $1.0\,\text{A}$, $3.0\,\text{A}$, $5.0\,\text{A}$ and $13\,\text{A}$. Which fuse should be selected?

Oct/Nov 2023

An electrical heater has a current of $5.0\,\text{A}$. It is linked to the mains supply using a flexible cable that is able to carry up to $15\,\text{A}$. The mains circuit itself can carry up to $30\,\text{A}$. Several fuses are available for protecting the heater’s cable. Which fuse would be the most suitable choice?

Oct/Nov 2023

The mains voltage is $120\ \text{V}$. Which fuse ought to be installed in an electric kettle with a power rating of $1.5\ \text{kW}$?

Oct/Nov 2024

The diagram displays the safety label fitted to an electric oven. This oven is connected to a mains electric circuit. A fuse is included in the circuit to safeguard the cabling and stop overheating if a fault occurs. At what point should the fuse be fitted, and what current rating should it have?

Oct/Nov 2024

Which component is unnecessary when using a double-insulated appliance?

Oct/Nov 2025

An electrical appliance displays a marking that shows it is double-insulated. Which statement is correct?

Oct/Nov 2025