Why stones are used in switch yard ?

1.TO AVOID THE GROWTH OF PLANTS AND GRASS NEAR THE YARD BECAUSE THIS WILL CREATE THE SHORT CIRCUIT.

2.THE ANIMALS ARE NOT WALKED OVER THE STONE ALSO TO AVOID THE SHOCK ACCIDENTS.

3. KEEP THE MOISTURE ALWAYS BOTTOM OF THE STONE TO REDUCE THE EARTH RESISTANCE

1.to reduce the vibration in transformer due to magnetriction.
2.to absorbed the heat radiated by radiator during cooling of oil.

So many reasons
1. Due to gravels no water on the surface.
2. No unwanted shrubs and bushes grow.
3. It is a good insulator so reduce hazard due to step and touch potential.
4. Provide protection from reptiles.
5. In case of leakage transformer oil it absorb.