GUIDELINES FOR CHEMICAL EARTHING PROCEDURE
Chemical earthing closely
resembles the pipe earthing system, but it incorporates a specialized chemical
compound known as GEM (Ground Enhancing Material) instead of the traditional
charcoal and salt backfill material. The introduction of the chemical compound
eliminates the need for constant water pouring to moisten the backfill, making
it a hassle-free and maintenance-free earthing system.
For comprehensive information on
earthing, please refer to the provided link.
Understanding Electrical
Earthing: Types and Systems
The effectiveness of the earth
resistance is primarily influenced by the soil resistivity and the type of
electrode deployed. Conventionally, cast iron plates, CU leads, or GI pipes are
utilized as electrodes for earthing. Consequently, regular watering and salting
of the earth pit become crucial to maintain low earth resistance. However, the
upkeep of earth electrodes poses numerous challenges due to the following
reasons:
A typical installation
necessitates four types of earthing (Safety, System, Electronic &
Lightning).
In many urban commercial
projects, earthing can only be established in basements. In cases where open areas
are used for earthing, landscaping conceals or hides the earth electrodes. Even
if the electrodes are accessible, there might be a lack of willingness or
effort to conduct regular maintenance.
The practical limitations
mentioned above often result in irregular watering and salting of the
electrodes. Moreover, the provided salt gradually dissolves over time due to
rainfall (sometimes within 2-3 years). As a consequence, the resistance
increases, rendering the earthing system ineffective.
Therefore, it is advisable to opt
for Maintenance-Free Earthing Solutions. Such systems achieve maintenance-free
status by treating the soil surrounding the critical electrode area.
ENHANCING EARTH CONNECTION
(GROUND IMPROVEMENT MATERIAL)
The effectiveness of a robust
earthing system largely relies on the quality of the Backfill compound, as
emphasized in IEEE 142. The type and caliber of the Backfill compound directly
impact the long-term dependability of the grounding setup. To achieve lasting
stability, both IEEE and BS standards advocate the use of ground enhancement
material or conductive concrete with a resistivity of < 0.12 Ohm mtr around
the electrode. Ground enhancement materials, particularly carbon-based ones,
offer permanent solutions without any chemical leaching into the soil.
International standards
acknowledge that treating an area of approximately 75 to 100 mm surrounding the
Electrode with ground enhancement materials featuring low resistivity can
significantly reduce the earth resistance, typically within the range of 25 to
40%.
IEC 62561-7 prescribes a series
of tests for the backfill compound, ensuring it remains free from any harmful
chemicals.
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