What is earth electrode ?
The conductor which is inter in the ground to make connection to the mass(surface) of the earth is called earth electrode.
Pipe conducting gas, water or inflammable liquid , sprinkler pipe ,metallic enclosure of cables ,conductor for lighting arrester should not be used for Earthing or as earthing pipe or rod.
Let’s, For better understanding, we discuss some type of Electrode.
Types of Earth Electrode
1 .Pipe Electrode
Pipe electrode comprises galvanized pipe.
The pipe earth electrodes size of internal diameter should not be less than 39 mm and pipe earth electrode length must be minimum 2.5 m.
Electrode holes of 12 mm diameter are drilled at the spacing of 150 mm.
These all holes are drilled alternative in the two planes .
This type of electrode is under the ground vertically at the minimum depth of 1.25 meter .
There should not be any coating of the cover or any insulation over the pipe.
2. Rod electrode
This type of electrode is in the form of a rod. Rod electrode is inter vertically in the ground.
It’s diameter should be 16 mm minimum if it’s made by material of iron or steel and its should be 12.5 mm minimum if it is made of copper material.
On road electrode should not be any insulating coating of enamel or not any paint of color.
It’s inter at depth of 1.25 meter minimum under the ground.
3 . Stripe Electrodes
This type of electrode is made of bare copper stripe.its size is 25 mm х 1.6 mm minimum and its cross sectional area should be minimum 3 .
Strip electrode length should be such that it gives low earth resistance and it is inter in the ground with horizontal trench dug up at the depth of 2.5 m.
4. Plate Electrode
This type of electrode is from the plate and this plate is made of galvanized iron or copper.
Its size is 600 mm х 600 mm for both material copper and galvanized iron plate but the thickness is 3 mm when it is made of copper and 6 mm when it is made of galvanized iron.
Plate electrode is inter in the ground with vertically at the depth of 1.5 m minimum and earthing lead is connected with the plate with help of nut and bolt.
Connected bolt and nut are made of copper if the plate is of copper and made of galvanized iron if the plate is made of galvanized iron.
Earthing lead is brought out through the galvanized iron .
Coil Electrode is a coil of GI wire of SWG size and Diameter of the coil is kept 50 mm .
115 turns are closely wound that reason the length of the coil becomes 450 mm.
It is inter vertically under the ground at the depth of 1.5 m minimum.
6. Concrete Encased Roads or Wire
Concrete resistivity becomes almost equal to 3000 ohm cm at 20 degree under the ground which is less than average earth resistivity.
So that plate at which the resistivity of the earth will be more , the road or wire is encased in concrete and inter in the ground instead of using the bare road or coil.
So the resistivity will decrease , so the rain forcing road of foundation of the building and tower are mostly used as the earth electrodes.
This suitable connection should be made at the rod of foundation and brought out .
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