Electrical Earthing

Earthing:

Earthing can simply be defined as the process of protecting against unwarranted spikes and bouts of electricity that can cause damage to life and property. Therefore it is important to remember these key differences between the two. One needs to understand that they both are referring to the same process. A deeper understanding of electric potential can prove useful in this method.

Grounding:

Grounding is similar to Earthing, by which insulation against accidental currents is achieved. The main live wire is connected to a power supply to power an appliance, however, the other portion of the wire is led under the earth. This is done in case of an accidental cut in the circuit, to avoid overloading and other dangerous side effects.

The key difference between earthing and grounding is that the term “Earthing” means that the circuit is physically connected to the ground which is Zero Volt Potential to the Ground (Earth). Whereas in “Grounding” the circuit is not physically connected to ground, but its potential is zero with respect to other points.

Difference between Earthing and Grounding

          Earthing.                                 Grounding

This method protects the human being from electrocuted.	This method protects the entire power system from malfunctioning.
Earthing contains zero potential.	Grounding does not possess any zero potential.
The earth wire used is green in colour.	The wire used for grounding is black in colour
Earthing is primarily used to avoid shocking the humans.	Grounding is primarily used for unbalancing when the electric system overloads.
Earthing is located under the earth pit, between the equipment body underground.	It is located between the neutral of the equipment being used and the ground

Why is an Earthing Necessary?

Earthing is an important component of electrical systems because of the following reasons:

• It keeps people safe by preventing electric shocks
• It prevents damage to electrical appliances and devices by preventing excessive current from running through the circuit
• It prevents the risk of fire that could otherwise be caused by current leakage

Earthing is an important component of electrical systems because of the following reasons:

 It keeps people safe by preventing electric shocks. 

It prevents damage to electrical appliances and devices by preventing excessive current from running through the circuit.

Mostly, the galvanised iron is used for the earthing. The earthing provides the simple path to the leakage current. The shortcircuit current of the equipment passes to the earth which has zero potential. Thus, protects the system and equipment from damage.

Advantages of earthing

From a technical perspective, earthing has some excellent advantages, resulting it in becoming a mainstream practice in the electrical industry.

•  The electrical system is related to the potential of the general earth mass and cannot reach a different potential. The potential of the earth is zero volts and is known as the neutral of the electricity supply. This helps in keeping the balance.
•  Another advantage is that metal can be used in electrical installations without having to worry about conductivity. Though metal is a good conductor of electricity, proper earthing ensures that metal parts not meant to be used for current transfer can be included in the system. This is done by providing a separate path for this faulty current, enabling its immediate detection and stoppage.
•  In cases of surges in the voltage, high voltages can pass through the electricity circuit. These kinds of overload can lead to damaging of devices and danger to human life. When earthing is installed with the electrical installations, the current is routed through a different path and does not affect the electrical system.
•  An electrical circuit has to be connected together with a lot of attention to the kind of reactions each transformer may have in response to any action on the part of any other transformer. The earth is an ever-present conductive surface and helps configure these relationships between different electrical sources and makes them easier to handle.

Connection of the neutral to earth 

The neutral conductor must be earthed at the substation and at other locations as necessary to ensure that the total impedance between neutral and earth does not exceed 10 ohms. In determining the impedance between the neutral and earth all connections of the neutral to earth should be taken into account, including: •  The earth connection at the substation •  The earth connections on the distribution system •  The earth connection at the consumer’s installation.

                      EARTHING SYMBOL

Resistance-earthed neutral (India)Edit

A resistance earth system is used for mining in India as per Central Electricity Authority Regulations. Instead of a solid connection of neutral to earth, a neutral grounding resistor is used to limit the current to ground to less than 750 mA. Due to the fault current restriction it is safer for gassy mines. Since the earth leakage is restricted, leakage protection devices can be set to less than 750 mA . By comparison, in a solidly earthed system, earth fault current can be as much as the available short-circuit current.

The neutral earthing resistor is monitored to detect an interrupted ground connection and to shut off power if a fault is detected.