Installation with High Resistance of Earth

Installation with High Resistance of Earth Points : installation with high resistance of earth Danger now exists on the exposed metalwork because the fault current of 4.2 amps flow through a resistance of 50 ohms in the install the metalwork and earth. The first indication that a fault has occurred is when someone earth. The first indication that a fault has occurred is when someone touches the metal work and gets a severe or possibly fatal shock.

This shows that an earthing system which has a high resistance path is virtually the same as having no earthing system at all, and just as dangerous. A low resistance earth path then, is essential and this is the primary requirement of an earthing system. Generally an earthing system comprises three parts the earth continuity conductor, the earthing lead and the earth electrode.

A sketch of part of a typical installation is given in order to show the purpose of each part.

Thus, through the combination of earth continuity conductor, earthing lead and earth electrode, the exposed metalwork is connected to earth, and the lower the combined resistance, the more efficient will be the protective device. Each of these three parts of an earthing system will now be considered in detail.