Topic 4.5 - Dangers of Electricity Flashcards
How is damaged insulation a hazard?
Sections of wire can be left exposed, and contact can result in electric shocks or pose a fire hazard.
How does overheating occur?
High currents cause the wires to heat up, melting the insulation and potentially causing a fire.
How do damp conditions pose a hazard?
Water can conduct a current, causing electric shocks etc.
What is a fuse?
A thin piece of wire which overheats and melts if the current is too high.
How should the rating of a fuse be chosen?
It should be slightly higher than the current used by the device in the circuit.
What is a circuit breaker?
An automatic electromagnetic switch which breaks the circuit if the current is above a set value.
What are advantages of circuit breakers over fuses?
- They can be reset and used again
- They operate faster
What is an earthing wire?
A wire which creates a safe route for current to flow down to the ground if a short circuit is produced, preventing electric shocks.
How do earth wires deal with surges?
They have a very low resistance, so in surges a lot of current flows through them, blowing the fuse and disconnecting the circuit.
