A refrigerator has its metallic cabinet connected to earth by a wire of resistance 0.50 Ω. Accidentally, the insulation of the live conductor breaks and the cabinet is directly connected to the live wire (230 V, 50 Hz). A person standing barefoot on a wet floor (body resistance 5.0 kΩ to earth) touches the cabinet.
(a) Assuming the earth connection is intact, draw an equivalent circuit showing all resistances involved and calculate the current that flows through the person’s body.
(b) The same accident occurs but the earth wire has become open-circuited. Calculate the body current now, taking the person’s resistance as unchanged.
(c) The current of 30 mA through the human body is considered the upper safe limit. Using your answers, discuss quantitatively how effective earthing prevents a fatal electric shock in this case.