Overloading and short circuit

Which situations shows that current could go through the body?

• Direct contact with a grounded surface

• Direct contact with live parts of the installation

• Accidental contact with damaged wires that are seemingly not live

• All of the above

At home, you noticed that a portion of an electrical wire is worn out, exposing its metallic part. What do you think might happen if you will just ignore this problem?

• short circuit may happen

• circuit is of better condition

• overloading may not happen

• nothing happens when someone touches the wire

Which statement about circuit breaker is not true?

• It protects the user from being electrocuted.

• it is a switch which will ‘trip’ when there is excess current flowing through.

• it creates short circuit.

• it cuts off electrical supply when the electrical appliance is damaged.

What electrical circuit condition in which current returns and takes the path of metal casing of an appliance?

• short circuit

• series circuit

• parallel circuit

• grounded circuit

Which of the following directs any excess current in the metal casing of appliances to the ground?

• fuse

• earthing

• circuit breaker

• electric sockets

What is a circuit breaker?

• A type of light switch.

• A switch used in an electrical appliance that uses large current.

• Used to turn on or off the electrical supply to the whole house.

• Used to switch off the electrical supply to one part of the circuit when current in that part of the circuit is too large.

Which is a result of overloading of electrical appliances?

• high performance of equipment

• inadequate current supply

• overheating of wires and fire may occur

• none of the above

The diagram below show the three wires of an electrical mains supply connected to an electric heater. A current of 4A is flowing from the supply through the “live” wire.

Which pair shows the correct corresponding currents of X and Y in the “neutral” and “earth” wires when the heater is working normally.

• 4A, 0A

• 4A, 4A

• 2A, 2A

• 0A, 4A