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air terminal
An air terminal is part of a lightening protection system that attracts
lightening strikes.
air-termination rod, air-termination conductor
See air terminal.
bonding
Bonding is a connection where you connect the electrically conductive parts
of systems together galvanically to maintain an as equal as possible electrical potential
between the parts. Bonding increases electrical safety and minimizes differential
voltages.
conductive plate
A conductive plate is a copper sheet plate used as a special ground
electrode on mountain tops or on bare rock when the ground electrode cannot be
buried.
conductivity
Conductivity measures the material's ability to conduct electric current.
When conductivity is low, resistance is high, and vice versa.
down conductor
A down conductor is part of a lightning protection system that conducts the
lightning current from the air terminal to the ground electrode.
earth conductor
Earth conductor is a British English term. See ground electrode.
earth electrode
Earth electrode is a British English term. See ground electrode.
earth plate
Earth plate is a British English term. See conductive plate.
earth rod, earth lead-in rod
Earth (lead-in) rod is a British English term. See ground rod.
earthing
Earthing is a British English term. The American English term is grounding.
See electrical safety grounding and grounding.
electrical safety grounding
Electrical safety grounding is grounding that reduces touch voltages in
mains powered systems and enables the safety components inside the system to operate properly in
fault conditions.
ground electrode
A ground electrode is part of a lightning protection system and has direct
electrical contact with the ground, conducting and dispersing the lightning current into the
ground. Ground electrode can be implemented by means of ground rods and conductive plates, for
example.
ground potential rise
Ground potential rise is the phenomena of a large current flowing to ground
through a ground electrode. The potential rise is highest at the point where current enters the
ground, and declines with distance from the source. The change of voltage over distance can
injure a person due to the voltage developed between two feet, or between the ground on which
the person is standing and a metal object. Ground potential rise is a hazard to people and
equipment.
grounding
Grounding is the physical connection of an electric circuit to the
ground.
grounding resistance
Grounding resistance is the property of the grounding system to ground to
conduct current to ground. The goal is to achieve the lowest feasible grounding resistance value
for a certain site or application.
impedance
Impedance is the measure of the opposition that is presented to a
(lightning) current when voltage is applied. In the context of lightning and grounding, the
lower the impedance, the better.
inductance
Inductance is the property of a conductor by which a change in the current
flowing through it creates a voltage in the conductor and in nearby conductors.
IT system
An IT system is a power distribution system where there is no connection
between the ground and the equipment, except possibly through a high impedance route, and there
is a direct connection between the ground and the electrical device being supplied. The letter
‘I’ stands for 'isolation' and ‘T’ stands for ‘terra’ (Latin for ‘earth’). IT system is defined
in International standard IEC 60364. In an IT system, the line and neutral are isolated from
ground.
lightning protection grounding
The purpose of lightning protection grounding is to attract lightning,
disperse the lightning current to different paths, and ground the current.
lightning protection system, LPS
A lightning protection system is a system that reduces or prevents physical
damage to a structure due to lightning. An external lightning protection system intercepts
direct lightning strikes to the structure, and conducts the lightning current from the point of
strike to ground. Equipment of an external lightning protection system include an
air-termination system, a down-conductor system, and an earth-termination system (ground
electrode system).
LPS
See lightning protection system.
safety grounding
See electrical safety grounding.
soil resistivity
Soil resistivity is the property of soil to conduct electricity. Soil
resistivity is dependent on the mineral and moisture content of the soil. Soil resistivity is
not homogenous.
step voltage
Step voltage is the voltage between the feet of a person standing near an
energized grounded object. Step voltage poses a risk of electric shock. See also touch
voltage.
TN system
A TN system is a power distribution system where the connection between the
ground and the power-supply equipment is direct and the connection between the ground and the
electrical device being supplied is such that there is a direct connection to neutral at the
origin of installation.
touch voltage
Touch voltage is the voltage between an energized object and the feet of a
person in contact with the object. Touch voltage poses a risk of electric shock. See also step
voltage.
TT system
TT system is a power distribution system where there is a direct
connection between the ground and the power-supply equipment (such as a generator or a
transformer) and between the ground and the electrical device being supplied. The letter ‘T’
stands for ‘terra’ (Latin for ‘earth’). TT system is defined in International standard IEC
60364. In a TT system, the neutral wire is connected to the ground at the supply end
(transformer or generator) or on the site.