1. Electrical Safety in the Home

3. From this lesson you will learn:
The effects of electric shocks.
How a plug should be wired correctly.
How a plug works.
How electrical safety devices work.
The various faults that can develop.

4. Spot the Dangers

6. Electricity
Electricity is a flow of electric charges (electrons) along a wire.

7. Electricity
Electricity is a flow of electric charges (electrons) along a wire.

8. Electricity
Electricity is a flow of electric charges (electrons) along a wire.

9. Electricity
Electricity is a flow of electric charges (electrons) along a wire.

10. Electricity
Electricity is a flow of electric charges (electrons) along a wire.

11. Electricity
Electricity is a flow of electric charges (electrons) along a wire.

12. Electricity
Electricity is a flow of electric charges (electrons) along a wire.
Current (I) is a measure of amount of electrons passing and is measured in amps (A).
e.g. I = A or 3 mA.

13. Electric Shocks Electricity can be dangerous and can kill!!
An electric shock can:
Affect your muscles.
Affect your nerves.
Paralyse you.
Stop your heart beating.
You can get an electric shock from anything which is plugged in or connected to the mains supply.

14. Factors in lethality of electric shock
Current. The higher the current, the more likely it is lethal. Since current is proportional to voltage when resistance is fixed (ohm's law), high voltage is an indirect risk for producing higher currents
Duration. The longer the duration, the more likely it is lethal — safety switches may limit time of current flow
Pathway. If current flows through the heart muscle, it is more likely to be lethal.
Very high voltage (over about 600 volts). This is an additional risk over the simple ability of high voltage to cause high current at a fixed resistance. Very high voltage, enough to cause burns

15. If someone suffers an electric shock:
Turn off the power source.
Put the person in the recovery position.
Dial 111 for an ambulance.

17. Answers

18. Electrical Safety
The wires which carry electricity consist of two parts:
The metal (ie good conductors) wires.
The plastic coating round the metal wires.
The plastic coating acts as an insulator which prevents people from being electrocuted.

19. The Fuse
A fuse is a thin piece of wire which will melt when too much current passes through it. Eg A 3A fuse will melt when the current is greater than 3A.
Designed to protect people and equipment by melting and breaking the circuit so electricity no longer flows.

20. Circuit breakers
protect people and equipment by springing open and breaking the circuit so electricity no longer flows.

21. electrocuted damaged devices
Electrical Safety Check
The fuse.
The switch.
Plastic coating
Circuit breaker.
The earth wire.
1. Name three safety devices that appliances may have.
2. Copy and complete the following notes filling in the blanks using words from the word bank.
electrocuted damaged devices
These are designed to stop you from being
and to prevent the appliance from being
2. These devices are designed to stop you from being electrocuted and to prevent the appliance from being damaged.

22. current amps melt fuse wire current electricity
Electrical Safety Check
3. Copy and complete the following notes filling in the blanks using words from the word bank.
current amps melt fuse wire current electricity
A is a thin piece of which will when too much passes through it.
A fuse is a thin piece of wire which will melt when too much current passes through it.
is a flow of and is measured
in (A).
Current is a flow of electricity and is measured in amps (A).

23. The NZ Plug Most electric cables normally contain three wires:
live wire (brown).
neutral wire (light blue).
earth /ground wire (green/yellow).
The fuse and the switch are connected to the live wire.
If the fuse is blown, or the switch is off, then the electricity cannot reach the appliance.
The live and neutral pins allow electricity to pass through the appliance and cause it to work.
The earth wire does nothing unless something goes wrong

24. What can go wrong!
The most dangerous thing that can happen is that the live wire can become loose inside an appliance and touches the casing.
This makes the casing LIVE!
If you touch the LIVE casing, you could be electrocuted as you are providing a path for the electricity to flow.

25. Prevention
To prevent electrocution, the earth wire is connected to the casing of the appliance.
If the live wire touches the casing, the earth wire provides a path for the electricity to flow.
This blows the fuse and switches the appliance off, leaving you safe.

26. Electrical Safety Check
4. What 2 safety devices control the amount of electricity that enters an appliance?
The fuse.
The switch.
5. Which wire are these 2 safety devices connected to ?
The live wire.
6. Which wire allows electricity to enter an appliance?
The live wire.

27. Electrical Safety Check
7. Copy and complete the following notes filling in the blanks using words from the word bank.
switched fuse live blown prevent
connected switch fuse live wire
The fuse and switch must be connected to the live wire to prevent the appliance from remaining live when the fuse is blown or the appliance is switched off.
The and must be to the
wire to the from remaining
when the is or the appliance is
off.

28. Lightning rods / Earth wire
carry the electricity through wires to the ground to get rid of it as quickly as possible.

29. Fault Spotting

30. 8. Describe the most dangerous thing that can happen to an appliance.
The most dangerous thing that can happen is that the live wire can become loose inside an appliance and touches the casing.
9. What happens to you if you touch the casing of an appliance which is live and why?
If you touch the LIVE casing, you could be electrocuted as you are providing a path for the electricity to flow.
10. Describe how the earth wire acts as a safety device?
The earth wire is connected to the casing of the appliance. If the live wire touches the casing, the earth wire provides a path for the electricity to flow. This blows the fuse and switches the appliance off, leaving you safe.

31. Earth wires
carry away electric current if it escapes from its circuit.
They are attached to appliances to take electricity if there is a short circuit and the appliance becomes live.