112. Vol 1 of the Firefighters Training Manual contains information about electricity. Describe ‘Ground Gradient’.
112. When a live wire lies on the ground, the energy released fans out through the ground from the point of contact. The effect is similar to that when a pebble is dropped into calm water and waves or ripples roll out from the point of contact. As with the ripples in the water, the strength of the voltage diminishes as the distance from the point of contact increases. The effect of this voltage drop is called ground gradient. If a person walks within this area, the difference in voltage of the 2 points of contact is the electric shock that will be received.