Earthing & Lightning Protection Glossary

Name: ELOX Earthing Services
Address: Shop No. 005/A, S.R. No. 131/9, Amardeep Apt, Dongarpada Rd, Bilal Pada, Nallasopara East, Palghar, Maharashtra, 401209, IN
Telephone: +91-9324818093

20 terms used in Indian earthing specifications, defined in plain English — for engineers, contractors and anyone reading a tender document.

Glossary

Fundamentals

Earthingalso called Grounding: Earthing is the deliberate connection of electrical equipment to the general mass of earth, so that fault current has a low-resistance path to flow away safely. It protects people from electric shock, protects equipment from damage, and gives protective devices a path large enough to trip. "Grounding" is the North American term for the same thing.
Earth electrodealso called Earthing electrode, Ground rod: An earth electrode is the conductor buried in the soil that makes the actual electrical contact with the earth. It is normally a driven rod, but may also be a plate, strip or buried conductor. Everything else in an earthing system exists to connect equipment to this electrode.
Earth resistance: Earth resistance is the resistance between an earth electrode and the general mass of earth, measured in ohms. A lower value means fault current dissipates more readily. The value required depends on the type of installation and is set by the governing standard and the project specification, not by a universal figure.
Soil resistivity: Soil resistivity is a measure of how strongly the soil at a site opposes electrical current, expressed in ohm-metres. It is the largest single variable in earthing design: the same electrode installed in low-resistivity clay and in dry sand will give very different earth resistance. It should be measured before an earthing system is specified.
Equipotential bonding: Equipotential bonding is the practice of electrically connecting exposed metalwork so that everything a person can touch sits at the same voltage. It prevents dangerous potential differences arising between two metal parts during a fault or lightning strike.

Glossary

Electrodes & materials

Copper bonded earth rodalso called Copper bonded electrode: A copper bonded earth rod is a steel core with a copper layer molecularly bonded to its surface. It combines the driving strength of steel with the conductivity and corrosion resistance of copper, which is why it is the most widely specified electrode for general industrial and commercial installations. Coating thickness is commonly specified at 250 microns.
GI earthing electrodealso called Galvanised iron electrode: A GI earthing electrode is a steel electrode protected by a zinc (galvanised) coating. It is the most economical of the common electrode types and is suited to non-aggressive soils, where the zinc layer gives adequate corrosion protection for the required design life.
Pure copper earthing electrode: A pure copper earthing electrode is made of solid or copper-clad copper rather than a coated steel core. It offers the highest conductivity and the best corrosion resistance, making it the choice for saline, acidic or otherwise aggressive soils and for critical installations, at the highest material cost.
Chemical earthing: Chemical earthing is an earthing method in which the electrode contains a conductive compound and is installed with a backfill compound packed around it. Compared with conventional earthing, which relies on the surrounding native soil alone, it lowers earth resistance and keeps it more stable through seasonal moisture changes. It is used where soil resistivity is high or the ground is rocky.
Backfill compoundalso called Earth enhancing compound: Backfill compound is a conductive material packed around an earth electrode to lower and stabilise its resistance. It increases the effective contact area with the soil and retains moisture through dry seasons, reducing the seasonal drift that otherwise pushes earth resistance out of specification.
Earthing pit chamberalso called Inspection chamber: An earthing pit chamber is the housing installed at ground level over an earth electrode so the connection can be inspected and tested without excavation. Chambers are typically FRP or concrete, fitted with a removable cover rated for the traffic load at that location.

Glossary

Lightning protection

Lightning protection systemalso called LPS: A lightning protection system is the complete installation that intercepts a lightning strike and conducts it safely to earth. It comprises three parts: air terminations that receive the strike, down conductors that carry the current, and an earth termination network that dissipates it into the ground.
Air terminationalso called Lightning arrester, Air terminal: An air termination is the part of a lightning protection system designed to be struck — typically a rod, mast, catenary wire or mesh on the structure. Its placement determines the volume of the building that is protected.
ESE lightning protectionalso called Early Streamer Emission: ESE (Early Streamer Emission) lightning protection uses a terminal designed to launch an upward leader earlier than a passive rod would, and is claimed to protect a larger radius from fewer terminals. It is covered by separate national standards; the conventional method described by IEC 62305 uses geometric coverage instead.
Down conductor: A down conductor is the conductor that carries lightning current from the air termination to the earth termination network. Multiple down conductors spaced around a structure share the current and reduce the risk of side flashing to nearby metalwork.
Exothermic welding: Exothermic welding is a method of joining conductors using a self-contained high-temperature chemical reaction, requiring no external power. The resulting joint carries current as well as the conductor itself and does not loosen or corrode at the interface, which makes it the preferred method for buried and inaccessible earthing connections.

Glossary

Standards & testing

IS 3043: IS 3043 is the Indian Standard code of practice for earthing, published by the Bureau of Indian Standards. It covers earthing system design, the selection and installation of electrodes, earth resistance requirements, protective conductors, bonding, and testing. It is the standard cited in most Indian electrical specifications and tender documents.
IEC 62305: IEC 62305 is the international standard for protection against lightning, published in four parts covering general principles, risk management, physical damage to structures, and protection of electrical and electronic systems. It defines lightning protection levels and the design of air termination, down conductor and earth termination systems.
Fall-of-potential testalso called Three-point method: The fall-of-potential test is the standard method of measuring earth resistance, using an earth resistance tester and two auxiliary spikes driven at defined distances from the electrode under test. It is carried out after installation to confirm the design value has been achieved, and repeated periodically thereafter.
TN, TT and IT systems: TN, TT and IT are the standard classifications for how an electrical installation is earthed, defined in IEC 60364. They describe the relationship between the supply earthing point and the exposed conductive parts of the installation, and determine which protective measures against electric shock apply.