Earthing
4 Minutes
Earthing and electric shocks explained for kids: learn how charges discharge and why plugs have a third pin. An English science lesson.
- How a charged comb attracts paper and discharges onto metal
- Why metal appliances give shocks and how earthing protects us
- Why the third pin in a three-pin plug is bigger and thicker
What this lesson teaches
Earthing is a safety connection that directs electric charges and leaking current from an appliance's metal body safely into the ground. It prevents people from getting an electric shock by offering current an easy route away from the device.
Discharging and electric shocks
When built-up charges on one object are taken away by another object, the process is called discharging. Appliances like televisions and refrigerators have metal bodies with internal wiring, and damaged wires can leak current and produce charges on the metal surface. Electric current travels easily through water and metal, and human bodies contain a high level of water. Touching charged metal allows the current to flow through the body to the ground, resulting in an electric shock.
How earthing protects us
- A wire coming from the ground connects to the large top hole of a power socket.
- The top pin of a three-pin appliance plug connects directly to the metal body of the machine.
- Any extra charges that appear on the metal casing pass through this thick pin straight into the earth.
- Electricians also wear rubber slippers to prevent current from passing through their bodies to the earth.
Paths that leaking current can take
- The current can complete the normal electrical circuit and flow out through it.
- The current can pass straight through a person touching the appliance to reach the ground.
- The current can travel along the earth wire and go directly into the ground.
- The current chooses the earth wire because it always takes the easiest available path.
Why the third pin is bigger and thicker
The top earth pin on a three-pin plug is made longer and thicker so that it disconnects last when pulled from a socket. If all three pins detached at the same time, charges collected in the appliance could not discharge. With this design, the two lower pins disconnect first, allowing any remaining charges to discharge safely into the ground through the earth pin. This special shape keeps users safe from shocks even after an appliance is turned off.