What is an appliance and how does it work?
An appliance is a machine that does a household job. It changes electric energy into another form. A heater, kettle or iron makes heat, a fan or mixer makes motion, a bulb makes light. The rate at which an appliance uses energy is its power, in watts (W).
Power = voltage x current, so P = V x I. At 230 V, a 1150 W kettle draws 1150 / 230 = 5 amperes.
Safe use of appliances: the rules
- Dry hands, dry floor. Water carries electricity to your body.
- Switch off, then plug in. Switch off, then unplug by holding the plug, not the wire.
- Check the cord. A cracked or bare wire must not be used.
- Do not overload. A usual home socket is for about 10 A at 230 V, which is 2300 W. Add the watts of everything on one board.
- Use three-pin plugs with earth for metal appliances.
- Keep away from water and heat: never use a hair dryer near a bath.
- Never push a metal object into a socket.
A fuse or circuit breaker (MCB) cuts the current when it is too high. It protects the wire. If it trips, find out why before you switch on again.
Simple maintenance anyone can do
Always unplug before cleaning.
- Kettle: hard water leaves a white layer called scale. Boil water with a little vinegar or citric acid, leave it, then rinse well. A scale-free kettle boils faster and saves electricity.
- Fan: wipe the blades and the guard with a damp cloth when it is off, since dust makes it slow and noisy.
- Refrigerator: keep the door seal clean and defrost when thick ice builds up.
- Washing machine and mixer: clean filters and jars after use. Do not overload them.
- Iron: let it cool before storing and empty the water tank.
Simple repair: what is safe and what is not
Some jobs are fine with an adult: tightening a loose handle, changing a bulb (switch off and let it cool), changing a fuse of the correct rating after unplugging, or replacing a worn plug with help from an adult.
Never open a switched-on appliance, work inside a TV, microwave or geyser, or fix a damaged wire yourself. Call a trained electrician. If someone gets a shock, switch off the main switch first or push them away with a dry wooden stick. Never touch them directly. Then call for help.
Read the manual. It tells the power, the voltage and the safe way to clean.
Try it
Home check (with an adult). Read the label of three appliances. Write each watt rating. Add them. Is the total below 2300 W? Look at each cord and plug for cracks.
In the 3D: drag the devices slider and watch the bar cross the red limit. Press Descale and compare the boiling time.
Key formulas and definitions
- P = V x I
- I = P / V
- Energy (kWh) = Power (kW) x Time (h)
- Safe load of one socket about 230 V x 10 A = 2300 W
Worked examples
1. A kettle is rated 1150 W at 230 V. What current does it draw?
I = P / V = 1150 / 230 = 5 A.
2. An extension board has a heater (1200 W), an iron (800 W) and a kettle (1000 W). Is it safe for a 2300 W limit?
Total = 1200 + 800 + 1000 = 3000 W. This is more than 2300 W, so it is overloaded and unsafe. Use different sockets.
3. A 2 kW heater runs for 3 hours. How many units (kWh) does it use?
Energy = 2 kW x 3 h = 6 kWh, which is 6 units.
Common mistakes
- Pulling the plug out by the wire, which breaks the cord inside.
- Plugging many heavy devices into one extension board.
- Touching a switch with wet hands.
- Cleaning or fixing an appliance while it is still plugged in.