Chemical Earthing, also known as Maintenance Free Earthing

PROCEDURE FOR CHEMICAL EARTHING

Chemical earthing is like to the pipe earthing system. A chemical compound also known as GEM (Ground Enhancing Material) is used in the place of charcoal and salt backfill material. The chemical compound eliminates the necessity of moistening the backfill by water pouring as in the case of conventional pipe electrode system. That's why, chemical earthing is called as maintenance free earthing.

To know the details about the earthing, follow the link. 

What is Electrical Earthing: Types of Electrical Earthing and Type of Earthing System?

The value of earth resistance purely depends on the soil resistivity and type of electrode used. Conventionally, for earthing, cast iron plate, CU lead/GI pipe is used as an electrode. Hence, regular watering and charging of the earth pit with salt is very essential to maintain low earth resistance. Regular Maintenance of the Earth Electrodes is becoming a challenging preposition due to the following reasons.

 1.   A typical installation requires 4 types of Earthing (Safety, System, Electronic & Lightning)

2.   In many commercial projects in the cities, the earthing is possible only in basements. In projects, where the open area is used for earthing, landscaping is done, completely sealing / hiding the earth electrodes. Even where the electrodes are accessible, willingness to maintain is either lacking or not happening.

Obviously, due to these practical constraints, watering of electrode and charging with salt is not being done regularly and the salt provided also dissolves over a period of time due to rain (in many places, within 2-3 years). This increases the resistance and makes the earthing totally ineffective.

Hence, it is advisable to go in for Maintenance free Earthing Solutions. The Maintenance free earthing is possible by treating the soil surrounding the critical area of the electrode.

 

SOIL TREATMENT (GROUND ENHANCING MATERIAL)

The technology to achieve a good earthing mainly depends on the Backfill compound as it influences the critical area around the electrode as mentioned in IEEE 142. The type and quality of Backfill compound determines the long-term reliability of the grounding system. For greater degree of permanence, IEEE/BS standards recommend ground enhancement material or conductive concrete with resistivity of < 0.12 Ohm mtr to be used around the electrode. The carbon-based ground enhancement materials are permanent and do not leach any chemicals into the ground.

International standards recognize, that, treating an area of about 75 to 100 mm surrounding the Electrode with ground enhancement materials having low resistivity will significantly reduce the earth resistance, generally in the region of 25 to 40%.

The IEC 62561-7 for backfill compound recommend a series of tests to ensure the compounds do not contain any harmful chemicals.