1. Equipment Circuit Breaker printable DEMOS Mr Earth Powerpack Fuse wire
Ammeter
Wires

2. Recap: What are the key differences between AC and DC electricity
Recap: What are the key differences between AC and DC electricity? Write down your answers.
Demo fuse wire melting.
Ask students to describe what they see
If no fuse wire show this video: it is very short and just reiterate what is happening.

3. 4 6 8 Lesson intentions: Why are circuit breakers better than fuses?
Date and title: Circuit breakers and Fuses
6 April, 2019
S t e p s
t o
S u c c e s s
Learning outcomes:
Explain why different fuses are required for different electrical devices in simple terms.
Describe why a short circuit inside a device presents a hazard.
Discuss in detail the hazards associated with poor electrical wiring. 4 6 12 8
Key words: Fuse, Circuit breaker, Earth, Live, Neutral

4. Bigger picture Topic Fuses and Circuit breakers ACDC Plugs
Electrical Power
Topic
Electricity in the home
Energy Transfer
Appliances and efficiency

5. thin wire with high resistance
How does a fuse work?
A fuse is a built-in weak point in a circuit.
thin wire with high resistance
The image shows a glass fuse, which is commonly used in cars but not with mains electricity. The advantage of this type of fuse is that the fuse wire is visible.

6. The Fuse
When the wire melts, all current is stopped from reaching the appliance and switches it off – the circuit is broken.
The fuse stops a large current from flowing through an appliance, which could cause wires to overheat, melt or catch fire.

7. Fuses
Fuses have a rating based on the amount of current they will allow through. For example, a 13A fuse will allow a maximum of 13 amps of current to flow through. If MORE than this tries to flow through, the wire heats up and melts, breaking the circuit and protecting the appliance

8. Circuit Breakers
Circuit breakers are fitted in newer homes. They measure the difference in current in the live and neutral wires. If the difference is too great, an electromagnetic switch opens (‘trips’) which stops the flow of current. They work a lot faster than fuses and can be reset easily
Discuss with students about their own homes do they know where the breakers are?
Describe them and how they work when a powercut happens

9. Give students a print out and then describe the pathway of electricity through the breaker.
Students need to give a written description in their books of how the circuit breaker works.
Can be answered in a 6Mark style
This can be purple penned afterwards

10. Starter: DEMO TIME! Everyone around the front
Mr Earth.
Set powerpack to 2v
Demonstrate Mr Earth to describe how the Earth wire keeps us safe using double insulation
Discuss the fact that potential difference moves through the path of least resistance.. Wires have a lower resistance than the body so electricity will 'choose’ that path
Use this to describe in more detail why the Earth Wire is important, Why there is sometimes 2 cores (appliances that don’t need to be Earthed) and that appliances with metal cases ALWAYS have an earth cable)

11. Oven
Use this to help describe Mr Earth and how earth wiring creates a return path to ground.
It may heelp to draw this on a whiteboard or use the interactive board to annotate as you describe

12. 1) Describe how a fuse works
Compare!
What are the advantages and disadvantages of fuses and circuit breakers.. They do essentially the same thing but are used in different places.. American appliances for example don’t use fuses.
1) Describe how a fuse works
2) Describe the advantages and disadvantages fuses and circuit breakers