Practical electricity
Electrical heating, power, energy, cost, household hazards, protection and safe mains wiring.
Learning goals
- Explain electrical heating in common appliances
- Apply P = VI
- Apply E = VIt
- Calculate electrical energy and cost in kWh
- Identify the hazard from damaged insulation
- Identify the hazard from overheating cables
- Identify the hazard from damp conditions
- Explain how fuses and circuit breakers protect circuits
- Choose and justify an appropriate fuse rating
- Explain why metal casings are earthed
- Explain why double-insulated appliances do not need an earth wire
- State the meanings and roles of live, neutral and earth
- Describe the wiring of a mains plug
- Explain live-wire placement of switches, fuses and circuit breakers
G3 Science (Physics) · Topic 14
Begin with the complete topic lesson. Then try a short check, use the feedback to review one idea and come back later for another attempt.
Before you begin
Build the idea in order
- Heating, power and energy
- Electricity cost
- Hazards and protection
- Safe mains wiring
Lessons
Practical electricity
Electrical heating, power, energy, cost, household hazards, protection and safe mains wiring.
Check your understanding
Practical electricity topic check
Check the required topic capabilities and get focused practice for ideas that need another look.
What to remember
- Use P = VI for power, E = VIt for energy in joules, and kW × h for energy billed in kWh.
- Choose the smallest suitable fuse rating above an appliance's normal current.
- Earthing provides a low-resistance fault path; double insulation prevents accessible parts from becoming live.
- Live is brown, neutral is blue and earth is green/yellow; earth normally carries no current.
- Switches, fuses and circuit breakers belong in live so opening them isolates the appliance from the dangerous conductor.
Topic and syllabus information
Practical electricity is Topic 14 in K326 / K327 Physics component · 2027.
The lesson and questions stay at the depth required for this course.
Reviewed 9 Aug 2026
Course and syllabus information
- Course
- SEC G3 Combined Science Physics component
- Edition
- SEC G3 Combined Science Physics component 2027