SA5 - Earthing

What is the purpose of electrical earthing or grounding?

• To protect the personnel from overload-circuit current

• To protect the apparatus and personnel from the high voltage surges and lightning discharge

• To provide the easiest path to the flow of open-circuit current after the failure of the insulation

• To protect the personnel from open-circuit current

Answer explanation

To protect the apparatus and personnel from the high voltage surges and lightning discharge

What is an earth leakage circuit breaker?

• A circuit that detects earth leakage and disconnects power

• A circuit that leaks electricity to the ground

• A circuit where the neutral wire is disconnected

• A circuit where the live wire touches the earth

Answer explanation

A circuit that detects earth leakage and disconnects power

What are examples of exposed conductive paths?

• Concrete walls

• Wooden floors

• Water heater

• Metallic armours

Answer explanation

Exposed conductive paths include water heater piping because they can conduct electricity and pose a risk of electric shock if not properly grounded or insulated.

What is the purpose of bonding in electrical systems?

• To generate electricity

• To protect against lightning strikes

• To join two electrical conductors together

• To increase electrical resistance

Answer explanation

To join two electrical conductors together

What is the main purpose of equipment earthing?

• To provide adequate protection to individual electrical devices

• To reduce energy consumption in individual electrical devices

• To increase electrical resistance in individual electrical devices

• To prevent lightning strikes towards individual electrical devices

Answer explanation

The main purpose of equipment earthing is to provide adequate protection to individual electrical devices

What is system earthing in electricity supply systems?

• Connecting parts of the electric circuit with each other

• Connecting parts of the electric circuit with water

• Connecting parts of the electric circuit with the ground

• Connecting parts of the electric circuit with the sky

Answer explanation

Connecting parts of the electric circuit with the ground

What is the TN-S system in earthing classifications?

• The neutral of power supply with connection of earth only at one point to the source

• No earthing system provided by power distributor (at source)

• The consumer's earthing terminal is connected to the metallic armour of the distributor's cable (at source)

• The neutral and earth are combined in one conductor at the source

Answer explanation

The TN-S system in earthing classifications involves the neutral of power supply with connection of earth only at one point to the source

What is the TT system used for?

• Special lighting applications

• Consumer power supply

• Telecommunication applications

• Underground power supply

Answer explanation

The TT system is used for Consumer power supply, making it the correct choice among the options provided.

What are examples of grounding electrodes?

• Rod and pipe electrodes

• Metallic armours

• Concrete walls

• Wooden floors

Answer explanation

Grounding electrodes examples include rod and pipe electrodes, which are commonly used to provide a path for electrical currents to safely dissipate into the ground.

What affects the earth resistance of an electrode?

• The type of metal used in the electrode

• The color of the electrode

• The temperature of the surrounding air

• The resistance of the ground electrode itself

Answer explanation

The resistance of the ground electrode itself directly affects the earth resistance of an electrode.