Electrical Power
Volts times amps equals watts - the link between electricity and real work, heat and cost.
Why this matters
Where it occurs
Power calculations appear when sizing heaters, checking motor loads, reading energy bills and verifying that wiring and breakers can carry the load.
Why calculate it
Power is what electricity actually delivers - heat, motion and light. Current alone does not tell you the full story.
What decision it supports
Is this circuit overloaded? What size breaker? How much does running this equipment cost per shift?
What happens if it is wrong
Underestimating power means undersized conductors and protection - the classic recipe for overheating and fires.
The concept
Electrical power is the rate at which electrical energy becomes work or heat. For a resistive load, P = V x I - a 230 V heater drawing 10 A delivers 2300 W.
The same power can be expressed through Ohm's Law as P = I² x R, which shows why current is the enemy of wiring: losses grow with the square of the current.
Energy is power over time: kilowatt-hours. A 2.3 kW heater run for 6 hours uses 13.8 kWh - multiply by the rate to get the cost.
Formula
Electrical Power
P = V x I
- P = Power (watts (W))
- V = Voltage (volts (V))
- I = Current (amperes (A))
Worked example
Problem: A heater draws 10 A from 230 V. What power does it use?
- Identify the formula: P = V x I.
- Substitute: P = 230 x 10.
- Calculate: P = 2300 W = 2.3 kW.
2300 W. Wiring and protection must be sized for this continuous load.
Quick solve: practice it
A 5 A motor winding has 8 Ω of resistance. What power does it dissipate?
Quick-solve habit: calculate, then ask yourself - does this answer make sense in real units?
Games that use this mathematics
Apply the calculation inside a workplace simulation.