Volt, amp, watt, kilowatt-hour… These words are everywhere — on your panel, your bill, your appliances — but what do they really mean? Here’s the simplest explanation you’ll read.
Electricity is like water in a hose
The best analogy: picture a garden hose. The pressure is the voltage. The flow of water is the amperage. The power of the jet (pressure × flow) is the watt. And the amount of water used over time is the kilowatt-hour — what you pay for.
Each one, in plain terms
⚡ Volt (V) — the pressure
The “force” that pushes electricity. In Quebec, standard outlets are 120 V; big appliances (dryer, range, EV charger) are 240 V.
🌊 Amp (A) — the flow
The amount of current flowing. Your service capacity is measured in amps: 100 A, 200 A…
💪 Watt (W) — the power
What an appliance uses at a given moment. The magic formula: Watts = Volts × Amps. A baseboard is often 1,500 W.
🧾 kWh — what you pay
One kilowatt-hour = 1,000 watts for 1 hour. It’s the unit on your Hydro bill. A 1,500 W baseboard on for 1 h = 1.5 kWh.
Three places these words count
- Your panel (in amps): it has a maximum capacity (100 or 200 A). Too many hungry appliances at once and the breaker trips.
- Your appliances (in watts): each has its needs. That determines the right circuit and breaker size.
- Your bill (in kWh): you don’t pay for power, but for the amount consumed over time.
Your appliances, in watts
Small
LED bulb ≈ 10 W · Charger ≈ 5 W · TV ≈ 100 W · Refrigerator ≈ 150 W
Medium
Microwave ≈ 1,200 W · Toaster ≈ 1,200 W · Baseboard ≈ 1,500 W · Kettle ≈ 1,500 W
Big (240 V)
Water heater ≈ 4,500 W · Dryer ≈ 5,000 W · Range ≈ 8,000 W · EV charger ≈ 9,600 W
Why a breaker trips, in plain terms
Every circuit has a limit. A typical 15 A circuit at 120 V can supply about 1,800 W (15 × 120). Plug in a 1,500 W toaster and a 1,500 W kettle on the same outlet, and you’re asking for 3,000 W: the breaker cuts to protect you. That’s not a defect — it’s its job. If it trips repeatedly, it’s a sign you need to spread the load better… or add a circuit.
We turn numbers into safety
Load calculation, right breaker size, circuit matched to each appliance: our team makes these numbers work so your installation is safe and compliant. CMEQ · RBQ certified, serving Greater Montréal, Laval and the North Shore.
A question about your installation?
We explain it plainly, assess, and advise — no jargon. Free quote.
The most common questions
What’s the difference between a watt and an amp?+
The amp measures current flow; the watt measures power used. They’re linked by voltage: Watts = Volts × Amps.
What is a kilowatt-hour (kWh)?+
It’s 1,000 watts used for 1 hour, the unit billed by Hydro-Québec. A 1,500 W appliance on for 1 hour uses 1.5 kWh.
Why is my panel measured in amps?+
Because amperage represents the maximum current flow your service can safely supply — hence 100 A or 200 A services.
How do I calculate an appliance’s consumption?+
Multiply its power (watts) by the hours of use, then divide by 1,000 for kWh. Ex.: 1,500 W × 2 h ÷ 1,000 = 3 kWh.
Why are the dryer and EV charger 240 V?+
Because they need a lot of power. At 240 V, you deliver the same power with less amperage, allowing suitable, safe wiring.
How many watts does a house use?+
It varies a lot with heating and appliances. What matters isn’t the total, but that your service (in amps) can supply peak demand — the job of a load calculation.
Why does my 15 A breaker trip?+
Because you exceed its capacity (about 1,800 W at 120 V). Two hungry appliances on one circuit is enough. Spread the load or add a circuit.
How do I read an appliance’s power rating?+
Look for the label (often at the back or underneath): it shows watts (W) or amps (A) and voltage (V). Watts = Volts × Amps if you only have those two.
