The primary purpose of an earthing or grounding system is to achieve safety from fatal electrical shock and reliability (stability, reduced damage, or fire). These objectives can be achieved through a well-designed earthing system which takes into consideration various factors such as the location and application where it is to be implemented.
What is Earthing (or Grounding )?
In a well designed and installed electrical system, a low impedance return path for fault energy to its respective source is mandatory. This path is known as earthing (or Grounding in US). It minimises fault traversal into an un-prescribed circuit thereby saving the electrical network from severe damage and accidents.
In case of surge voltage (due to lightning strikes, line faults, etc), grounding or earthing can be understood as the path for transmitting the sudden discharge of electricity, by means of low resistance electric cables or wires, to the earth.
Benefits of Accurately Designed and Installed electrical systems
Following are some of the significant benefits of a proper earthing system
- Helps to achieve safety from touch and step potential: Correctly designed and installed earthing system eliminates the hazards caused due to step and touch Potential
- Trips the Protection system at right time: For protection circuit, earthing system is the reference point. Correctly designed and installed earthing system eliminates the untimely tripping of protection system thus saving life, livestock and assets from incidents, fatal accidents, equipment down time, unintentional trips and blackouts.
- Reduces Equipment Aging and Increases Production efficiency: Keeps equipment healthy, unstressed and allows it to perform for the intended time and output
What are the design criteria for an earthing system?
The design criteria for constructing an effective earthing system are –
- Location of construction
- Soil compaction
- Soil sodacity, calcicity, porosity, humidity
- Soil resistivity
- Highest possible fault energy
- Material used for construction
For installation of earthing system an important criterion to consider is the type of earth enhancing compound to be used. The earth enhancing compounds (EEC) as per best practices are:
- Permanent EEC (as per IEEE 80:2013 14.5 (d) clause) – Curec+®
- Maintenance-Free EEC (IEEE 80:2013 14.5 (b) clause) – Curecon®
- Bentonite-based EEC (IEEE 80:2013 14.5 (b) clause) – Curenite™
- Conventional Earthing (Salt & charcoal) (IEEE 80:2013 14.5 (a) clause)
An accurately designed and installed earthing system is important across various sectors such as oil refineries & petrochemicals, multi-billion-dollar skyscrapers, large scale industries, smart cities, precision industries like pharma, public transport systems such as rail or metro and Defence. While building this system we must ensure adherence to safe design criteria and use of products conforming to standards to reduce incidents, fatal accidents, production or performance loss and increase the reliability of operations which in turn helps to achieve better profits and receive a premium on being a safe industry.