LATEST EARTHING ELECTRODES IN THE MARKET
Grounding is the process of electrically connecting any metallic object to the earth by the way of an earth electrode system. The National Electric Code requires that the grounding electrodes be tested to ensure that they are under 25-ohms resistance-to-ground (Earth). It is important to know that aluminum electrodes are not allowed for use in grounding.
The standard driven rod or copper-clad rod consists of an 8 to 10 foot length of steel with a 5 to 10-mil coating of copper. This is by far the most common grounding device used in the field today. The driven rod has been in use since the earliest days of electricity with a history dating as far back as Benjamin Franklin.Driven rods are relatively inexpensive to purchase, however ease of installation is dependent upon the type of soil and terrain where the rod is to be installed. The steel used in the manufacture of a standard driven rod tends to be relatively soft. Mushrooming can occur on both the tip of the rod, as it encounters rocks on its way down, and the end where force is being applied to drive the rod through the earth. Driving these rods can be extremely labor-intensive when rocky terrain creates problems as the tips of the rods continue to mushroom. Often, these rods will hit a rock and actually turn back around on themselves and pop back up a few feet away from the installation point.
Grounding plates are typically thin copper plates buried in direct contact with the earth. The National Electric Code requires that ground plates have at least 2 ft2 of surface area exposed to the surrounding soil. Ferrous materials must be at least .20 inches thick, while non-ferrous materials (copper) need only be .060 inches thick. Grounding plates are typically placed under poles or supplementing counterpoises.
UFER GROUND OR CONCRETE ENCASED ELECTRODES
Originally, Ufer grounds were copper electrodes encased in the concrete surrounding ammunition bunkers. In today’s terminology, Ufer grounds consist of any concrete-encased electrode, such as the rebar in a building foundation, when used for grounding, or a wire or wire mesh in concrete.
CONCRETE ENCASED ELECTRODE
The National Electric Code requires that Concrete Encased Electrodes use a minimum No. 4 AWG copper wire at least 20 feet in length and encased in at least 2 inches of concrete. The advantages of concrete encased electrodes are that they dramatically increase the surface area and degree of contact with the surrounding soil. However, the zone of influence is not increased, therefore the resistance to ground is typically only slightly lower than the wire would be without the concrete.
Concrete encased electrodes also have some significant disadvantages. When an electrical fault occurs, the electric current must flow through the concrete into the earth. Concrete, by nature retains a lot of water, which rises in temperature as the electricity flows through the concrete. If the extent of the electrode is not sufficiently great for the total current flowing, the boiling point of the water may be reached, resulting in an explosive conversion of water into steam. Many concrete encased electrodes have been destroyed after receiving relatively small electrical faults. Once the concrete cracks apart and falls away from the conductor, the concrete pieces act as a shield preventing the copper wire from contacting the surrounding soil, resulting in a dramatic increase in the resistance-to-ground of the electrode.
Water pipes have been used extensively over time as a grounding electrode. Water pipe connections are not testable and are unreliable due to the use of tar coatings and plastic fittings. City water departments have begun to specifically install plastic insulators in the pipelines to prevent the flow of current and reduce the corrosive effects of electrolysis. The National Electric Code requires that at least one additional electrode be installed when using water pipes as an electrode. There are several additional requirements including:
The electrolytic electrode was specifically engineered to eliminate the drawbacks of other grounding electrodes. This active grounding electrode consists of a hollow copper shaft filled with natural earth salts and desiccants whose hygroscopic nature draws moisture from the air. The moisture mixes with the salts to form an electrolytic solution that continuously seeps into the surrounding backfill material, keeping it moist and high in ionic content.
Remedies Earthing Systems Private Limited (RESPL) An ISO 9001:2008 Certified Company & Established in the year 2004 with its corporate office at Lucknow.
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