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GCSE Combined Science · key term
An automatic safety switch that opens the circuit when the current becomes too large and can be reset after the fault is corrected.
Used by Edexcel
Paper 5, Paper 6
Revise: A.c., d.c. and mains electricity safetyA circuit breaker also disconnects the supply when the current becomes too large, but it uses an automatic switch rather than a wire that melts. Unlike a blown fuse, it can be reset and used again once the fault has been corrected. These devices also reduce the risk of overheating and fire caused by excessive current.
For an earthing explanation, link each step: live wire touches metal case → current flows through the low-resistance earth path → fuse melts or circuit breaker trips → live supply is disconnected.
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