Lightning Protection

Vocabulary practice flashcards covering the components, design standards, electrical phenomena, and installation principles of Lightning Protection Systems.

Air Termination Network

The uppermost component of a lightning protection system—consisting of vertical rods, suspended wires, or a horizontal conductor mesh—specifically designed to directly intercept lightning strikes.

Down Conductor

A low-impedance conductor that routes intercepted lightning current along a direct, vertical path from the air termination network to the earth termination network.

Earth Termination Network

The portion of a lightning protection system intended to discharge and disperse lightning current into the general mass of the earth, including all components below the testing point.

Earth Electrode System

One or more conductive elements (such as vertical driven rods, buried metal strips, or foundation conductors) in direct electrical contact with the soil to dissipate lightning currents.

Equipotential Bonding

The permanent electrical interconnection between the lightning protection system and exposed structural metalwork, service pipes, or cable sheaths to eliminate dangerous potential differences.

Side Flashing

An electrical flashover or spark jumping between the lightning protection conductors and adjacent isolated metallic objects on a structure due to high potential gradient differences.

Test Joint

A detachable joint positioned in each down conductor (typically $1\text{ to } 1.5\,m$ above ground) to permit isolation and measurement of earth electrode resistance and continuity.

Reference Earth Electrode

An auxiliary earth electrode capable of being completely isolated from the main earth termination network for testing and verification purposes.

Ring Conductor

A continuous conductive loop installed around the perimeter of a structure above or below ground, serving to equalize voltage gradients and interconnect multiple down conductors and earth electrodes.

Surge Protection Device (SPD)

An internal protective device installed at main and sub-distribution panels to detect transient overvoltages and divert surge currents safely to earth before they damage sensitive equipment.

Zone of Protection (ZP)

The calculated volume surrounding a conductor within which it protects a structure against direct strikes by directing the lightning discharge to itself.

Protective Angle

The angle formed between the apex vertical conductor and the boundary of the conical zone of protection, treated as $45^\circ$ for structures with heights up to $20\,m$.

Rolling Sphere Method

An electrogeometric modeling method used to define the protected volume and strike interception points on complex structures or buildings exceeding $20\,m$ in height.

Re-entrant Loop

A severe bend or loop around architectural projections where the risk of the lightning current jumping across the loop arises when conductor length exceeds $8$ times the loop's open width ($8d$).

Lightning Protection Zone (LPZ)

A standardized spatial concept in IEC/EN 62305 classifying spaces by their electromagnetic hazard level, extending from unshielded outdoor areas to shielded internal rooms housing sensitive electronics.

LPZ 0

The exterior zone exposed to direct lightning strikes and unattenuated lightning electromagnetic fields, comprising rooftops and building facades.

LPZ 1

The internal screened building zone where direct strikes are prevented by the external LPS, and incoming conductive surges are attenuated using main service entrance SPDs and equipotential bonding.

LPZ 2

A further screened internal zone designed to protect highly sensitive equipment (such as data servers) through coordinated secondary SPDs, shielded cabling, and local equipotential bonding.

Type A Earth Arrangement

An earthing configuration composed of discrete vertical driven rods or horizontal radial strip conductors buried at multiple points, each connected to an individual down conductor.

Type B Earth Arrangement

A buried continuous ring earth electrode loop encircling the perimeter of the structure in contact with the soil for at least $80\%$ of its total length.

Type C Foundation Earth Termination

An earthing system integrated into concrete foundations that uses interconnected reinforcing steel (rebar) as a low-resistance, durable grounding electrode.

Cumulonimbus Charge Separation

The dipole charge distribution within a convective storm cloud where strong updrafts lift finer positively charged ice particles to altitudes of $6\text{--}12\,km$, leaving heavier negative charges concentrated near the cloud base at $1\text{--}6\,km$.

Stepped Leader

A channel of ionized air that advances downward from a thundercloud towards the ground in discrete, rapid bursts or steps prior to the primary lightning discharge.

Upward Streamer

An ionized streamer that launches upward from ground level or elevated structures to meet the descending stepped leader, finalizing the conductive path for the return stroke.

Negative Lightning

A cloud-to-ground flash occurring between a negatively charged cloud base and positively charged earth, accounting for approximately $90\%$ of all cloud-to-ground lightning events.

Positive Lightning

A powerful cloud-to-ground discharge initiating from high altitudes or cloud tops that features a single unstepped return stroke with currents frequently exceeding $250\,kA$.

Re-strikes

Consecutive electrical return strokes (up to $16$ observed) that travel down the established ionized channel in rapid succession during a single lightning flash.

Combined Earth Resistance Target

The mandatory maximum overall electrical resistance to true earth for an entire interconnected lightning protection earth termination network, required to be less than $10\,\Omega$.

Effective Collection Area

The extended plan area of a building calculated in all directions based on structure dimensions and height, used to mathematically evaluate the annual risk of lightning strike exposure.

Explosive Store Lightning Protection

A non-contact isolation protection design featuring a suspended vertical air termination on an isolated mast at least $2\,m$ from the building, a $30^\circ$ protective angle, and an isolated ring earth electrode.

Tall Brick Stack Lightning Protection

A system design for industrial chimneys over $20\,m$ (such as a $60\,m$ stack) requiring at least two down conductors, a cast iron top cap connection, intermediate horizontal band conductors with junction clamps, and earth electrodes.

Free-Standing Chimney Protection Rule

The design requirement mandating that any chimney projecting more than $4.5\,m$ above an adjoining roof or standing free must be provided with lightning protection regardless of standard risk assessments.

BS 6651 Warning Label

A permanent label affixed at the origin of the electrical installation stating that the structure is protected in accordance with BS 6651 and requiring maintenance of equipotential bonding.

Lightning Protection Level (LPL)

A set of design criteria (Levels I to IV) defined in EN 62305 where Level I provides the highest protection efficiency with smaller mesh sizes ($5\,m \times 5\,m$) and tighter down-conductor spacing ($10\,m$).