Electrical safety – shock current, earthing and RCD breakers

Design & TechnologyElectrical Engineering & SafetyAges 13–14

Four common household electrical accidents: touching a bare live wire, holding a metal-cased appliance with a leakage fault, repairing wiring without switching off the power, and a kite string catching on a power line. Students choose the body's resistance, whether insulated sandals are worn, and a protection measure (earthed appliance casing, 30 mA RCD breaker), then press Touch the wire to see the current I = U/R flowing through the body, its value in milliamps plotted on a danger-level scale, and the contact time. The RCD breaker cuts the circuit within 0.1 second, while earthing brings the touch voltage down to a safe level.