Electricity – Part 4


Watts and Kilowatts

We measure power in watts or kilowatts (1000 watts). It’s calculated by multiplying voltage times the current.


For example, a home with a 240v power supply and 100 amp service generates 24000 watts or 24 kilowatts.

A 1200 watt hair dryer using a 120v receptacle (outlet) would result in a 10 amp current flow.


I = 1200 / 120

10 = 1200 / 120


1000 watts = 1 kilowatt

If you use 1 kw for one hour, you consume one kilowatt-hour (kWh). If each kWh costs 10 cents and we use 500 kWh in a month, our electrical bill for that mouth is about $50.00

Wire Size (Gauge)

We use wires to move electricity around the house because they’re good conductors. The amount of amps that a wire can safely carry is determined largely by it’s diameter. A larger wire can handle more current, typically household circuits are designed to carry 15 amps over 14-gauge copper wire.