Lightning Protection and Earthing Systems

A sudden, temporary increase in voltage or current.

Areas around a structure that need to be protected from lightning strikes.

Connecting electrical components to the earth for safety and protection.

The opposition to the flow of current through the earth.

A metal pipe used as part of an earthing system.

A metal plate used as part of an earthing system.

An international standard for lightning protection.

A measure of a system's ability to handle lightning surges.

A device that protects electrical equipment from surges.

A network of interconnected earth electrodes forming a loop.

A measure of how well the soil conducts electricity.

Connecting an electrical system to the earth (ground) to prevent electric shock and damage.

A surface where the electrical potential is the same everywhere.

Electric current flowing unintentionally in an unwanted path in an electrical system.

A conductor used to connect an electrical system to the earth/ground.

The total resistance encountered by current traveling from an electrical system to the earth.

Resistance of the metallic electrode material used for earthing.

Resistance of the soil surrounding the electrode in conducting current to the earth.

Measure of a soil's ability to resist the flow of electric current.

A pipe used as a conductor for connecting to earth, often in pipeline applications.

R = (ρ / 2πL) [ln {(8L / D) - 1}], where ρ is soil resistivity, L is electrode length, and D is diameter.

Defined sets of maximum and minimum Lightning current parameters for protection measures against lightning strikes. This determines the level of protection needed.

The highest level of lightning current that protection measures can handle for each LPL.

The lowest level of lightning current that requires a specific LPL protection measure.

Different zones around a structure or equipment with varying levels of risk from lightning, guiding protection measures against Lightning Electromagnetic Impulse (LEMP).

External zone with the highest risk of direct lightning strikes.

External zone with a risk of partial lightning current.

Internal zones with lower risk of lightning strike, within the structure.

Connecting all metallic parts in a system electrically so they have the same electrical potential.

Connecting metallic parts to prevent dangerous voltage differences during lightning strikes.

All metal components in a system, like plumbing, electrical wiring, and appliances.

Electrical conductors used to create connections for equipotential bonding.

Devices that protect electrical systems against voltage surges.

A central point where various metallic systems are bonded together.

The system that connects to the earth to discharge excess electricity.

The space between metallic parts that prevents unwanted electrical conduction.

Minimum cross-sectional area required for protective conductors not part of the supply cable, either 2.5 mm² with mechanical protection or 4 mm² without.

The process of measuring the resistance to current flow through the earth using specialized instruments.

A four-terminal instrument with a voltage source and a meter to measure resistance (in ohms) of the earth.

A three-terminal method for measuring earth resistance, where the voltage drop across a known distance is measured.

Electrodes in a four-terminal earth testing setup that carry the current.

Electrodes in a four-terminal earth testing setup that measure the voltage.

Method to measure the opposition to current flow through the earth, often using a generator to overcome stray currents.

Unwanted electrical currents in the ground that can skew earth resistance measurements.

Device used to measure earth resistance and its effects in the soil.

Component of an earth tester that changes the direction of current flow, leading to AC testing.

Additional electrodes (typically rods) used to create a current flow path for resistance measurement.

Earth resistance testing method measuring current in a loop without disconnecting the earth cable from the system.

The initial, less bright discharge from a cloud to the ground during lightning.

The brighter, faster discharge from the ground to the cloud, following the stepped leader.

A natural electrical discharge between a cloud and the ground, or within a cloud.

The type of lightning that originates in a cloud and travels to the ground. It is a primary concern for S&T installations.

The process where the initial discharge from the cloud to the ground takes place in steps, stopping and then repeating in a zig-zag pattern.

The process where the air becomes ionized and conducts electricity. This is fundamental in enabling the lightning stroke.

The process of the electric field becoming stronger before a leader discharge occurs.

The upward-moving positive charge that neutralizes the negative charge from the stepped leader, creating a complete discharge path.

Air molecules that have gained or lost electrons, thus carrying an electric charge; crucial part of the conducting path during lightning.

When enough potential difference is built up, electrons and/or positive charges flow between different points in space.

Difference in electrical potential between two points. It is the force behind the electrons flowing.

At least 20 kg of bentonite clay should be used per earth pit associated with a pipe electrode for optimal earthing.

Using less bentonite clay initially results in lower resistivity readings, but resistivity increases over time.

A system of interconnected external earth electrodes, an internal equipotential busbar or ring in an equipment room, and connecting links, providing a low-impedance path for fault currents.

International standard outlining lightning protection, driven by risk assessments, considering the structure and connected systems, addressing transient overvoltages/surges.

Consists of four interconnected parts: general principles, risk management, physical damage/life hazard, and electrical/electronic systems within structures.

Introduces the standard, classifying damage types, outlining risks/losses, defining lightning current parameters, and relating damage/loss aspects crucial for risk assessments.

Different areas around a structure with varying levels of risk from lightning strikes, directing protection measures.

Zone closest to a structure, with a high risk of direct lightning strikes, handling full current and magnetic field.

Exterior zone, with a risk of partial lightning current or induced current and full magnetic field.

Zone with less chance of a direct strike. Handles induced current and dampened magnetic field.

Interior zone with the least risk of direct strikes, having very damped magnetic field due to distance.

Connecting all metallic parts in a system to have the same electrical potential, preventing dangerous voltage differences.

Devices that limit voltage transients at power-entry points to protect electrical installations.

System for connecting electrical components to the earth (ground).

Measure of a soil's ability to conduct electricity.

The interconnecting tape should be buried at least 500mm below ground level.

The interconnecting tape should be covered with an earth enhancing compound.

Measuring the resistance of the ground.

Main Equipotential Earth Busbar, the central point for interconnected earth pits.

A method to measure earth resistance using two auxiliary electrodes and a known current.

R = V/I, where R is resistance, V is voltage, and I is current.

Lightning Electromagnetic Impulse; the overall electromagnetic effects of lightning, including conducted surges (sudden voltage/current changes) and radiated electromagnetic field effects.

Sudden voltage changes caused by electrical switching actions, especially in inductive loads.

Electrical components (motors, transformers, drives) that store energy in magnetic fields, causing voltage surges during switching.

International standard for LEMP protection of electronic/electrical systems; integral to protecting against damage from lightning.

Transient overvoltages and currents, conducted through electrical systems, from lightning strikes.

Effects of electromagnetic fields generated by lightning strikes, impacting nearby electronic equipment.

An era where electronics and computers are widely used and integral, necessitating standards for protection like IEC 62305.

Increased use of electrical and electronic equipment makes structures vulnerable to lightning strikes affecting internal systems.

Devices that protect electrical equipment from voltage surges, enabling continuous operation during lightning activity.

To maintain zero potential for non-current carrying parts of electrical systems, preventing electric shock and providing a path for fault currents.

Earthing systems protect personnel from electric shock by grounding exposed parts, provide return paths for currents, and protect equipment from overvoltages by grounding surge arrestors.

To provide a safe path to ground for electrical equipment, protecting personnel from electric shock.

To provide a return path for fault currents, allowing protective devices to operate quickly and effectively.

To protect equipment from electromagnetic interference (EMI) and radio frequency interference (RFI) by grounding metallic components.

RDSO/SPN/197/2008 provides specifications for earthing systems in signal and telecom installations, based on IS 3043-1987.