Page 111 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Plate earthing: In this type of earthing plate either of copper or of G.I buried in to the ground at a depth not
less than 3 meter from the ground level. The earth plate is embedded in alternative layer of coke and salts for
a minimum thickness of about 15 cm. The earth wire (copper wire for copper plate earthing and G.I wire for G.I
plate earthing)is securely bolted to an earth plate with the help of bolt nut and washer made of copper , in case of
copper plate earthing and G.I in the case of G.I plate earthing.
List of materials used in plate earthing
1 60cm x 60cm x 6.3mm GI Plate OR 19mm dia GI pipe

2 12.7mm dia GI pipe
3 Charcoal
4 60cm x 60cm x 3.15mm Copper Plate Funnel
5 Wire mesh
6 Cement concrete (1:4:8)

7 6.3mm MS Rod
8 GI Cover hinged to GI frame

Methods of construction of plate earthing
Excavation on earth for a normal earth pit size is 1.5m x 1.5m x 3m.Use 60cm x 60cm x 6.3 mm GI plate. Make
a mixture of wood coal powder salt& sand all in equal part. The purpose of coal and salt is to keep wet the soil
permanently.
The salt percolates coal absorbs water keeping the soil wet. Care should always take by watering the earth pits
in summer so that the pit soil will be wet. Coal is made of carbon which is good conductor minimizing the earth
resistance.

Conductor salt use as electrolyte to form conductivity between GI plate coal and earth with humidity.
Sand has used to form porosity to cycle water and humidity around the mixture. Put GI plate of size 60cm x 60cm
x 6.3 mm in the middle of mixture.

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CITS : Power - Electrician & Wireman - Lesson 20-25