Fuses and Earthing

what are surges?

a sudden increase in current

why do surges happen?

- can happen when something changes in a circuit for example when an appliance is turned on or off

- can also happen because of a fault in the circuit or appliance

what issues can surges cause?

- they can damage an appliance

- cause a fire

- cause an electric shock

what are circuit breakers?

a component that breaks the circuit whenever there’s a surge

what are the advantages of circuit breakers?

they don’t get permanently damaged they just get ripped and turn off the circuit, so they can be reset

what are the downsides to circuit breakers?

more expensive

what are fuses?

a very thin piece of wire connected to the live wire that breaks the circuit when the current gets too high, as when current that’s too high flows through it it melts

how do fuses work?

if there’s a surge a huge amount of current will flow through the live wire and hence through the fuse, causing the wire of the fuse to heat up really quickly and because it’s thin it will melt which then breaks the circuit so no more current can flow

what are the benefits of fuses?

they’re simple and cheap

what are the downsides to fuses?

they’re permanently broken after a single surge meaning they have to be replaced each time

fuses come in different —— depending on what —— you want to break the circuit

ratings, current

what rating fuse would you use if your appliance had a current had a current of 3A and why?

a fuse of 5A so that the circuit will only break if there’s a surge of above 5A

what is double insulation?

when the entire appliance is covered in plastic casing so there are no exposed metal parts to be touched

if an appliance has double insulation does it still need an earth wire?

no, as plastic is an insulator so it doesn’t conduct electricity, so you can’t get an electric shock

what is earthing?

where an earth wire provides an alternative pathway for current to floe away, so that any excess charge is diverted back to earth through the earth wire and not to us

where on the appliance is the earth wire connected to?

the casing

What are some key safety precautions you should take when using electrical appliances at home?

• Turn off electrical appliances when not in use: This helps prevent overheating and reduces the risk of electrical fires.

• Avoid using appliances with a power rating higher than the circuit's capacity: This can cause overloads and increase the risk of electrical accidents.

• Don't touch electrical appliances, plugs, wires, or sockets with wet hands: Water is a good conductor of electricity, increasing the risk of electric shock.

• Ensure electrical appliances are in good condition: Check for exposed wires or damaged plugs. If there’s a fault, get it repaired before using.

• use fuses etc

Why is it important to insulate wires in electrical circuits?

• Prevents current leakage: The insulation ensures that the current flows through the wire without straying to other parts of the circuit or surroundings.

• Prevents electric shock: The insulation protects users from coming into direct contact with the conductive metal inside the wire, reducing the risk of electrical shock.