Practical electricity Flashcards
1
Q
What are some hazards of using electricity
A
Damaged insulation
- Exposed live wire can cause electric shock when touched
Cable overheating
- Overheated circuits can cause a fire
2
Q
What is the live wire
A
- Brown
- Usually at 240V
- Delivers current to the appliance
3
Q
What is the neutral wire
A
- Blue
- Usually at 0V
- Completes circuit by providing a returning path to supply
4
Q
What is the earth wire
A
- Green and yellow
- Low resistance wire connected to metal casing
- No current
5
Q
What is a fuse
A
- Safety device to prevent excessive current flow
- Needs to be replaced after it blows
- Fuse will melt and open the circuit when current exceeds its rated value
5
Q
Where are the switches, circuit breakers and fuses connected to
A
Live wire
6
Q
What is double insulation
A
- Enclosed in a plastic casing
- 2 layers of insulation to enclose all exposed ‘live’ parts
7
Q
What is a circuit breaker
A
- Electromagnetic switch that can automatically switch off electrical supply when there is excessive current flow
- Needs to be manually reset
8
Q
What is the earth metal casing
A
- Metal case that encloses electrical parts of appliance
- If live wire touches metal casing, current will flow to earth via earth wire and fuse will blow or circuit breaker will trip
- User avoids electric shock
9
Q
Why must switches, circuit breakers and fuses be connected to live wire
A
- Appliance is disconnected from high voltage of live wire when safety features are activated
- If safety devices not connected to live wire, appliance still connected to high voltage even when safety devices activated
