Kilowatt-Hour (kWh)
The unit your utility bills you for: one kilowatt of power used for one hour. The average US home uses about 850 – 900 kWh per month.
A kilowatt-hour is energy over time. Run a 1,000-watt appliance for one hour and you have used exactly 1 kWh; a 100-watt bulb takes ten hours to use the same. At typical residential rates of $0.12 – $0.25 per kWh, every always-on device has a real annual price tag: an old fridge in the garage can quietly cost $150+ a year.
kWh is the lens for diagnosing a high electric bill: the meter only records consumption, so something in the house is genuinely drawing it. Heat strips running because of a heat pump fault, a failed water heater element, or a pool pump on the wrong schedule are classic culprits.
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- Amp (Ampere) : The unit of electrical current: how much electricity is flowing through a wire at a given moment.
- Volt : The unit of electrical pressure pushing current through a circuit.
- 120V vs 240V : US homes receive two 120-volt legs from the utility.
- Voltage Drop : The loss of voltage along a wire run, caused by the resistance of the wire itself.