Electrical Earthing or grounding provides the safety of the personnel from the electric shock. It insures that the non currents carrying parts, such as equipment frames are always safe at ground potential even though the insulation fails.
In this video are some of the questions of Electrical Earthing system, you may be asked at a job interview, including a few technical questions to get you started.
Video source By- Learning engineering
1. Why do we need earthing?
Earthing is used to protect you from an electric shock. It does this by providing a path for a fault current to flow to earth. It also causes the protective device either a circuit-breaker or fuse to switch off the electric current to the circuit that has the fault.
2. What is ground in a circuit?
A ground is a direct electrical connection to the earth, a connection to a particular point in an electrical or electronic circuit, or an indirect connection that operates as the result of capacitance between wireless equipment and the earth or a large mass of conductive material.
3. How does grounding work?
You see current flows from the panel to the outlet or device to power it up. The neutral wire is the return path for unused current. In that instant, the short would cause the current to flow through the ground wire, causing a fuse to blow or a circuit breaker to trip.
4. How does earthing work in electricity?
A difference can occur when either current is flowing down the earth wire or through someone's body to ground, and back to the neutral point through the earthing system. Electricity flows only when the circuit is complete. And our body is a great conductor of Current. So electricity will flow through body to ground.
5. What is an earth bond?
Earth bonding is the act of connecting all metallic objects in a room, or house, to 'electrical earth'; usually a gas and\or water pipe. Gas and water pipes run through the earth so are connected to the same earth, eventually, as the electrical earth of an electrical circuit.
6. What is TT earthing?
The fault loop impedance is higher, and unless the electrode impedance is very low indeed, a TT installation should always have an RCD as its first isolator. The big advantage of the TT earthing system is the reduced conducted interference from other users' connected equipment.
7. What is the purpose of an electrical ground?
Distribution power systems may be solidly grounded, with one circuit conductor directly connected to an earth grounding electrode system. Alternatively, some amount of electrical impedance may be connected between the distribution system and ground, to limit the current that can flow to earth.
8. What is the earth wire used for?
The earth wire creates a safe route for the current to flow through if the live wire touches the casing. You would get an electric shock if the live wire inside an appliance, such as a cooker, came loose and touched the metal casing. This breaks the fuse and disconnects the appliance.
9. What is a ground wire used for?
The Ground Wire. The term ground refers to a connection to the earth, which acts as a reservoir of charge. A ground wire provides a conducting path to the earth which is independent of the normal current-carrying path in an electrical appliance.
10. What do you connect the ground wire to?
If a metal box was used, the box itself should be grounded. The bracket that holds the light would then be connected to the box, which would make the bracket grounded. Finally the ground wire from the fixture would attach to the bracket, grounding the fixture.