Earth Pit Construction

Earth pits are a very widely used method of earthing electric systems.  Earth pits provide a very low earth resistance and are very reliable.

The earth pit is constructed as follows:

Excavate a pit of approximately the following dimensions 70cms x 70 cms x 250 cms. 

Place a cast iron pipe electrode that is 2.5 metres long and of size 75 -125 mm diameter.  The pipe should be about 10 mms thick.

The pipe is placed vertically. 

A mixture of Bentonite and black cotton soil is mixed in the ratio of 1:6.  The pipe is filled with this mixture.  The space surrounding the pipe is also filled with this mixture.

The earth pit is an important part of any earthing scheme.  It should be maintained properly at regular intervals.  Earth resistance measurements should be taken periodically.