Earth Mat - Construction

Earth mat is a method of earthing,  It is used in areas with rocky soil, where it is difficult to excavate earth pits.  The earth resistance obtained with pits will also be above the required value.

Earth mats obtain the earth resistance with a large contact area.  The earth mats consists of a number of flat strips laid in the form of a grid.  The grid is placed in a trench which is about 75 cms deep.  The flats are made of mild steel and are of 75 x 8 mm size. 

The flats are welded to one another.   The low resistance is achieved by the increased contact area this method provides.

The earth resistance should ideally be less than 1 ohm.  The resistance value should be periodically checked and recorded.