What Is Earthing System?
In electrical engineering, the earth or ground is a references point in an electrical circuit from which voltage is measured and commons return path for electric current or a direct physical connection to the earth. In electrical installations, an earthing system or grounding system connects specific parts of that installation to the conductive surfaces of the earth for safety and functional purposes.
After explaining what earthing is, this article will focus on the purpose of earthing/grounding, good earthing practices approved earthing, and the main components, design, and functions of earthing/grounding system. Electrical earthing is referred to as the process of transferring an instantaneous discharge of electric current directly to the earth.
This transfer is accomplished with the help of a wire of low resistance. It is actually an arrangement by which an electrical installation is connected to a means of earthing. Although earthlings are sometimes used for functional purposes, it is more commonly in services for security purposes.
For example, in cases of telegraph lines, earthing is used as a conductor to save on the cost of the return wire on a long circuit. If there is a fault in the electrical installation, and there is no earthing system in this installation, a person may be harmed by electric shock by touching the damaged metal part, as the body of the power tool is traversed to earth.
The job of earthing is to provide an alternate path for fault current to flow to the earth.
Most of the time, galvanized irons are used for earthing. Earthing acts as a smooth passage of leakage current. The zero potential earth carries the shortcircuit current of the equipment. Thus, the earthing protects the system and equipment from possible damage.
What Does Earthing System Mean?
In power supply systems, an earthing system defines the electrical potential of conductors relative to the conductive surface of the earth. The choice of earthing systems has implications for the safety & electromagnetics compatibility of the powers supply.
Functions of the earthing system are to provide:
- Protective Earthing
- Functional Earthing
- Lightning protection
Earthing system regulations vary greatly between countries and different parts of electrical systems. Most low-voltage systems connect a supply conductor to the earth (ground). Earthing system is also known as the protective earth or grounding system.
Purposes Using of Grounding System:
In previous sections, we talked about what an earthing system is and what it does. Now we are going to list down some of the most important purposes for which earthing is in service. Electrical circuits are connected to the earth or indeed to the ground for some reason. Below are several reasons why it is important to use a grounding system.
- Personal Security
- Protection of the electrical system
- Protection of electromagnetic pulses
- lightning protection
- A sufficiently low impedance to facilitate satisfactory safety operation under fault conditions.
- Overvoltage protection, within reasonable range under fault condition
- Graded insulation in power transformers.
- Limit voltage to earth on the conductive material enclosing the electrical conductor or equipment.
Corrosionpedia Explains Earthing System:
The earthing system is the circuitry that connects parts of an electrical circuit to the ground. It affects the magnitude & distribution of short circuit currents through the system & the effect it creates on people in proximity to equipment and circuits.
An earthing system avoids this hazard by placing the exposed conductive surfaces of an appliance at earth’s potential. A functional pile of earth connections serves a purpose other than providing protection against electric shock.
A functional earth connection can carry a current during the normal operation of an appliance. Functional earth connections may be required for instruments such as surge suppression and electromagnetic-compatibility filters, some types of antennas, and various measurement instruments.
Earthing systems must be constructed in such a way and of such materials that they perform correctly throughout the expected lifetime, at a reasonable manufacturing cost. Required properties are:
- Low earthing resistance & favorable earth surfaces potential distribution.
- Adequate current carrying capacity
- Long durability
The durability of the earthing system mainly depends on its ability to withstand corrosion. Earth electrodes, being in direct contact with soil or water, operate in corrosive conditions. There are three main factors that determine the rates of corrosion of metal objects in soil:
- DC currents in the earth
- Chemical contamination of soil
- Electrochemical galvanic phenomena between different metals in soil
The choice of electrode materials is usually a compromise between the cost and durability of the earth electrode.
Types of Earthing Systems:
In the previous sections, we have come up with some of the important objectives and goals for which earthing is in service. We talked about the different types of protections that a grounding system provides. Now we are going to explain in detail the different types of earthing systems.
There are five basic methods for providing and providing the neutral of an electrical installation. The names and details of the five methods and their abbreviations are given below.
TN-S Earthing System
In this method, there’s are single points of connection between the supply neutral & earth on the supply transformer. Supply cables have separate neutral & earth protective conductors (SNE).
Basically, the neutral conductor is the fourth ‘core’, and the earth conductor forms a protective sheath. The subscriber may have one earth terminal attached to the service cable’s sheath or may have separate earth conductors.
In the UK & before the introductions of the Protective Multiple Earthing (PME or TN-C-S) system, the TN-S method was a fairly standard arrangement.
TN-C-S Earthing System
In this method, the supplies cables have combined neutrals & earth metal outer sheath with PVC covering. The combined neutral earth sheath is PEN (Protective Earth Neutral).
Supply to the customer’s premises will typically be TN-S, meaning neutral, and earth will be isolated, connected only to the service position. When neutral and earth combat within the complex, the system is TN-C.
PNB Earthing System
Protective neutrals bonding is actually variations of the TN-C-S system, which provides an earth terminal for the customer to connect to the supply neutral. But you have to remember that neutral is connected to earth only at one point. This arrangement is for the use of single subscribers with a transformer.
TT Earthing System
These methods are systems where the supply is made at only one point, but the cable sheath and the exposed metalwork of the subscriber’s installation are connected to the earth through a separate electrode that is independent of the supply electrode.
IT Earthing System
It is a system without a direct connection between the living parts and the piles of earth, but with its exposed conductive parts of the installations. Sometimes a high-impedance connection to the earth is provided to simplify the protection scheme required for earlier earth fault detection.
A customer who buys electricity expects good earthing. These are in view of the fact that there is a high risk involved in the use of electricity with poor earthing. All electricity suppliers must have approved earth electrodes at their facilities.
This means that the flash-over voltages, which can appear for a variety of reasons, are carried into the soil so that they do not cause any damage and/or injury.
An accepted earthing must include:
- low electrical resistance
- Ability to conduct stable voltage even when weather changes
- Long life expectancy, i.e. high resistance against corrosion
The selection of an earthing system can affect the safety and electromagnetic compatibility of the installation. That’s why our recommended option is the Apress Deep Earthing System.
Earthing System Functions and Design:
The earthing copper wire (5) is inserted and placed in the hardened steel tip (1). Extension rods (3) have guiding pins to enter the rear tube end to form a stable extension of the system.
Since the earthing resistance at the other end of the wire can be continuously monitored, driving down is interrupted when a satisfactory low resistance is reached.
The top extension rod (3) is pulled up and reused. Knocking-down studs (or sleeves) is normally made by a power hammer with a suitable driving stud (4) or sledgehammer and driving cap FS61 or FS62C.
Why Choose Elpress Deep Earthing System?
Some of the many benefits of the Apress Deep Earthing System are:
- No connection of earthing electrode or earthing wire
- Accepts large cross-section area, 16 – 95 mm2 wire
- It can be used for multiple wire types.
- long life expectancy
- Full control over Cu wire travel during drill down
- When Cu wire is used, the steel rods act as sacrificial anodes and protect the Cu wire from corrosion.
- Enables continuous resistance monitoring
- decrease in the potential difference at the surface of the earth
- Earthing resistance is seasonally-stable
- Very weight effective and easy to handle small driving rod segment
- Lower cost than other systems
- Some parts make driving simple and operationally reliable.
Importance of Earthing:
Earthing is necessary for the following reasons:
- Protect earthing personnel from short circuit current.
- Earthing provides the easiest path for shortcircuiting current to flow even after insulation failure.
- Earthing protects equipment and personnel from high voltage surges and lightning discharges.
Earthing can be done by electrically connecting relevant parts in the installation to a system of electrical conductors or electrodes placed near or below ground level. The grounding mat or electrode below ground level consists of a flat iron riser through which all non-current-carrying metal parts of the equipment are connected.
It occurs when fault current from the equipment flows through the earthing system to earth, thus protecting the equipment from fault current. At the time of a fault, the earth mat conductor rises to a voltage that is equal to the earth mat’s resistance multiplied by the ground fault.
The assembly is called earthing. The metal conductors connecting the parts of the installation to the earthing are called electrical connections.
Advantages of Earthing:
- Earthing is safe and is the best way to provide protection. We know that the earth’s potentials are zero and is assumed to be neutral. Since fewer devices are connected to the earth using a wire with a lower resistance, balance is achieved.
- Metals can be used in electrical installations without looking for their conductivities, and proper earthing ensures that the metal does not transfer current.
- A sudden increase in voltage or overload should not cause damage to the device and the person if proper earthing measures are taken.
- This prevents the risk of fire hazards that might otherwise be caused by the current leakage.
Frequently Asked Questions (FAQ)
The earthing system (UK and IEC) or earthing system (USA) connects some part of the electrical power system to the earth, usually an earth conductor, for safety and operational purposes.
Types of Earthing Systems
- TN-S Earthing System
- TN-C-S Earthing System
- PNB Earthing System
- TT Earthing System
- IT Earthing System
Importance of Earthing
Earthing system makes the equipment electrically shock free and gives you a safe place to stay. It saves human life from the danger of electrical shock, which can cause death, by blowing a fuse. It protects your electric equipment or devices.
Ensures the safety of electrical appliances and devices from the excessive amount of electric current.
Helps in the flow of electric current directly inside the ground.
Keeps the electric appliance safe from damage.
It protects building breakdowns from lightning.