electricity Flashcards
(8 cards)
a fuse is a safety device designed go
cut off the flow of electricity to an appliance if the current becomes too large (due to a fault or a surge)
how do fuses work
if the current in the wire becomes too large:
The wire heats up and melts
This causes the wire to break, breaking the circuit and stopping the current
whats an earth wire
an additional safety wire that can reduce the risk of being electrocuted
how does earthing work
A metal wire (earth wire) connects the casing directly to the ground.
The earth wire has very low resistance, so:
The fault current flows down the earth wire instead of through a person.
This large current causes the fuse to blow or the circuit breaker to trip.
The circuit is cut off quickly, making it safe.
circuit breaker consists of
an automatic electromagnet switch that breaks the circuit if the current exceeds a certain value
advantage of circuit breaker over fuse (2)
It doesn’t melt and break, hence it can be reset and used again
It works much faster
what is double insulation
2 layers of insulation
what is insulation
The conducting part of a wire is usually made of copper or some other metal
If this comes into contact with a person, this poses a risk of electrocution
To improve electrical safety wires are covered with an insulating material, such as rubber
