Dimension and quality of pipe
For pipe electrode, galvanized steel
pipe shall be of class ‘B’ Medium quality, having 50 mm dia. bore and the
length shall not be less than 2.45 metres. The top end shall be threaded and a
hole of 15 mm in diameter shall be drilled through at 10 cm from top end to
receive a 12 mm galvanized bolt.
The galvanized wire of No. 6
S.W.G. or copper conductor shall be connected securely on the cleaned surface
of pipe so as to make electrically sound conductor.
The bottom end of pipe shall be
chiseled out to facilitate easy penetration into soil, if required to be driven
into ground. A trench shall first be made 45 cm deep and then a hole for such
electrode shall be drilled by means of augur, in order to place the electrode
at an average depth of 30 meter below the ground level. The top end of the
electrode shall be at an average depth of 30 cm below the ground level. The excavated
and drilled area around the electrode shall be back filled and consolidated. Neither
the use of short piece of pipe nor any joint on earth lead conductor is permitted.
Where joint is unavoidable, the pipe shall be rigidly jointed by means of
screwed socket etc. as done by the plumbers.
The protective G.I. pipe shall
be filled with bituminous compound by approved make and brand, in order to make
it hermetically sealed. The molten compound shall be poured from the top end of
pipe topped up to overflowing.
The earth lead conductor from
electrode shall not be cut or terminated unless the same reaches in desired
length for making connection with earth bushingbar, switchboard, pole, service
bracket, lighting arrester or the object to be earthed.
The electrode shall be buried
or driven at least 2 meters clear from building or the object to be earthed. The
electrode and lead shall be kept free from paints, grease or like substance to
prevent the poor conductivity.
For the ease of examination of
earthing, provision shall be made, where
desirable, for an inspection pit, similar to those done by the plumbers.
