Fuses & earthing (Edexcel GCSE Physics): Flashcards
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Practise the cards
14 cards from this deck
Purpose of fuses & earthing
Purpose of fuses & earthing
Prevent overloads, protect against shocks/fire
What are electrical surges?
What are electrical surges?
Sudden increases in current
Causes of electrical surges
Causes of electrical surges
Appliance faults or circuit changes
Dangers from electrical surges
Dangers from electrical surges
Wires overheat/melt, causing fires or shocks
What causes a fuse to melt?
What causes a fuse to melt?
Current surge exceeds fuse rating
Which wire is the fuse connected to?
Which wire is the fuse connected to?
Live wire
Effect when fuse melts
Effect when fuse melts
Breaks circuit, cuts off live supply, isolates appliance
What is fuse rating?
What is fuse rating?
Maximum current fuse can handle before melting
How to choose correct fuse rating
How to choose correct fuse rating
Slightly higher than appliance's normal operating current
Purpose of earthing
Purpose of earthing
Fault current flows to ground, not through person
Which appliances must be earthed?
Which appliances must be earthed?
Those with metal cases
What is double insulation?
What is double insulation?
Plastic casing with no exposed metal parts
Wires in double insulated appliances
Wires in double insulated appliances
Live & neutral only (no earth wire)
Advantages of circuit breakers over fuses
Advantages of circuit breakers over fuses
Can be reset, react faster