Electrical safety

An electric hairdryer and an electric heater are linked to the mains supply, as illustrated in Fig. 7.1. The cable from the heater to the mains supply contains a live wire, a neutral wire and an earth wire.

May/June 2015

The diagram illustrates the wiring of a three-pin mains plug. It contains an error in the diagram. What is the error?

May/June 2016

An electrical appliance is connected to a wall socket. The plug has a fuse. What is the fuse’s main purpose?

May/June 2018

A fuse is one type of protection used in an electrical circuit.

May/June 2018

The cable for an electric cooker has a live wire, a neutral wire and an earth wire. When the cooker is operating properly, in which wires are the currents the same?

May/June 2019

The manufacturer of an electrical heater says that no more than one heater should be linked to the mains wiring through a single fuse. With just one heater in the circuit, the current is $9\,\text{A}$. The fuse rating is $10\,\text{A}$. Even though this warning is given, a second identical heater is connected, as shown. When the switch is closed, the fuse blows. The fuse is then changed for a $20\,\text{A}$ fuse. What occurs when the switch is closed?

May/June 2019

Fig. 6.1 shows the fuse fitted inside the plug of a hairdryer.

May/June 2019

The details printed on the rear of an electric room heater are: rating $220$-$240\,\text{V}$ $\sim 50\,\text{Hz}$ $4.2\,\text{A}$ What fuse rating would be appropriate for this room heater?

May/June 2021

A three-pin mains plug includes a fuse. A double-insulated device is attached to the plug by a cable. Which part of the plug is not linked to the cable?

May/June 2021

A metal kettle is connected to a mains socket using a plug that has a suitable fuse fitted. The kettle’s cable becomes damaged, and the fuse blows. Why does the fuse blow?

May/June 2022

The diagram illustrates a hairdryer. Which statement gives the reason that the hairdryer does not need an earth wire?

May/June 2022

A filament lamp is positioned above a polished metal surface, as shown in Fig. 8.1.

May/June 2023

What safety precautions should be followed when wiring an electric kettle with a stainless-steel outer casing?

May/June 2024

What does the earth wire in a plug connected to an appliance do?

May/June 2024

Fig. 5.1 shows a section of a circuit with a $240\,\text{V}$ a.c. mains supply linked to a lamp and two heaters with resistances of $40\,\Omega$ and $60\,\Omega$.

May/June 2024

Fig. 6.1 illustrates part of a mains circuit containing three lamps and a heater.

May/June 2025

A car’s headlamp circuit contains a $7\,\text{A}$ fuse. What is the function of the fuse?

Oct/Nov 2016

A house’s a.c. mains electricity system has three wires: live, neutral and earth.

Oct/Nov 2016

What is the reason that the metal casings of electrical appliances are earthed?

Oct/Nov 2017

In a lighting circuit, the switch is fitted into the live wire. Why is this?

Oct/Nov 2018

In a lighting circuit, the switch is fitted into the live wire. Explain why this is done.

Oct/Nov 2018

A lamp is linked to a mains plug. Where should the switch and the fuse be connected so that the lamp is safe to use?

Oct/Nov 2019

The diagram illustrates a copper lightning conductor fixed to a building. What is the reason that the lightning conductor is made of copper?

Oct/Nov 2019

A mains electric circuit has a circuit breaker installed instead of a fuse. Where is the circuit breaker placed, and what occurs when the current becomes too large?

Oct/Nov 2019

A washing machine cable has three separate conductors. One of these conductors contains a fuse.

Oct/Nov 2020

A washing machine is operating normally, with both the water heater and the motor switched on. It is connected to the mains supply through a cable.

Oct/Nov 2021

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

Oct/Nov 2022

For what reason is a fuse fitted in an electrical appliance?

Oct/Nov 2022

Three students give statements about appliances with double insulation. Student P: Appliances with double insulation do not require an earth wire. Student Q: Double insulation protects the user of the appliance from electric shock. Student R: The circuits in appliances with double insulation do not include fuses. Which of the students are correct?

Oct/Nov 2023

An electric kettle has an outer casing made of metal. Fig. 7.1 displays the kettle. Diagram labels: mains power supply, cable, electric kettle, metal outer casing. The heater inside the electric kettle is linked to a 230 V mains power supply and has a power rating of 2300 W.

Oct/Nov 2025