The earthing system is essential to prevent short circuits or reduce the damages caused by the failure of insulation. These protect the apparatus and devices from high voltage surges and restrict the effect of lightning discharge.
The best way to deal with earthing systems is to get the right installation parts from reputed earthing accessories manufacturers. Compromising with the installation accessories would lead to shock hazards and electrical fires and increase the repair or installation cost as the equipment gets damaged from voltage.
Electrical earthing consists of two non-current carrying parts, which are neutral, and these are:
- Neutral Earthing
- Equipment Earthing
Let’s learn about the electrical components of an earthing system to ensure complete safety and low impedance.
These are earth rods (either one or more), and often, along with this, earth plate or earth mat are included. Every piece is interconnected by earthing tape or cable and buried deep underground.
These pieces are selected based on the combined resistance value, and they must not exceed 1 ohm. The gap maintained between each of these rods are more than 6 meters and is subsequently attached to other earthing systems.
These are used in the final step of the earthing system, and their purpose is to dissipate the lightning discharge. They also dissipate earth fault current or static discharge voltage into the ground.
Earth electrodes used are of two types:
Ring type earth electrode
Here, you can find earthing conductors in a closed loop, and these are buried under the waterproof exterior part of the wall foundation. These can also be buried around the perimeter of the foundation, keeping a mark of 0.6 m.
All the earthing are connected to the ring, and at the service entrance, main switchboard rooms, and insulated connection flags are placed. These are made of identical earthing conductor material. Earth rods are connected to the ring to reduce the earth electrode resistance.
Functional earth electrode
These are placed separately from other earth electrodes but interconnected with a 470 spark gap. These mostly assist in ensuring proper earthing for digital processors and communication devices that involve computers.
Alternative earth electrodes used are copper plates and tape mats, which are readily available at earthing accessories manufacturers.
Main earthing terminals or bars
These are present in the main distribution room or also called the service entrance. All the earthing conductors are connected to the main earthing bar, along with protective and bond conductors. Two insulated main earthing conductors are attached to the earth electrode through testing joints.
The conductors must have the capacity to carry maximum earth fault current and attach to the final conductor temperature that should not exceed 160 deg. C for a minimum of 5 seconds. The main earthing conductor has to be a minimum of 120 sq. mm.
The main earth bar has to be in the form of a ring, and in an accessible position, the testing joints are placed between earthing terminals on every main earthing conductor.
Based on the regulations, the size of the conductors is set. These are not formed by conduit, ducting or trunking. Moreover, there has to be continuity in the protective conductor. So, a series connection is maintained from one piece of equipment to another.
Extraneous and exposed conductive parts are not used. In the case of voltage control meshes, the bare strip conductors are used for earth electrodes. Usually, the conductor is buried 1000 mm below the underground power cables, and those not buried are to be straightened right after installation.
The earth fault loop impedance has to be maintained so that any disconnection of protective devices on over-current occurs within 0.4 seconds. Moreover, at every utilization point, the earth fault loop impedance must disconnect within 5 seconds.
Equipotential bonding conductors
These are two types of supplementary equipotential bonding and main equipotential bonding:
Supplementary Equipotential Bonding
Through this bonding, all the extraneous conductive parts of the building are connected, including metallic water pipes, drain pipes, and every other service pipe. The list also includes cable trays and armor, dueling, metallic conduit and raceways, joined to the nearest earthing terminals. Moreover, these are done through equipotential bonding conductors.
Main Equipotential Bonding
In this type of bonding, the most important incoming and outgoing water pipes are connected to the main earth terminal through main equipotential bonding conductors. Along with this, other metallic service pipes are also connected.
These are used to fill up the holes and trenches that are dug around the earthing system. This helps to reduce the resistance surrounding the earth electrode and also increases the conductivity of the soil.
These soil enhancers have a great effect on increasing the surface area. In a high conductive medium, the metal electrode is encased to increase surface contact and improve dissipation.
Inspection Pits and Connecting Clamps
This is the point of connection that links the earthing conductor and the earth electrode. These inspection pits are used as a test point and are meant for the earth system. On the other hand, the connecting clamps are used to connect the earth electrode and the earth conductor. You can place your order from clamps at earthing accessories manufacturers.
This is basically a process of connecting two metals, and these are mostly copper to copper and copper to steel. The entire process is also known as the self-contained welding process, where a permanent connection is built rather than bolted or compression connections.
This is particularly used in substation gridwork construction and implemented for structures with equipotential bonding connections.
Earth Rod Seals
Earth rod seals are meant to create a watertight seal, but these are not always utilized. They create a seal between the earth electrode, earth rod and the waterproof membrane. The process is meant to restrict the seepage of groundwater.
Earth rod seals are used in case the inspection pit is going to be placed within the stricture. Thus, the earth electrodes will pass through the floor slabs and waterproof membrane.
The earthing system also requires electrically independent earth electrodes, which are meant for special cases. Further, termination fittings, welding kits, and other accessories are also used to secure the earthing system.
Remember that the earth wire and earth electrode should be of the same material. Further, you must get the best quality earthing system from IAC Electricals to prevent leakage of current or electrical accidents.