Finding the exact wattage of your appliances is essential for accurate Dimensionnement du générateur — and there are four reliable methods, ranked from most to least accurate.
Méthode 1: Read the Nameplate (Most Accurate)
Every electrical appliance sold in the U.S. is required by law to have a nameplate or label showing its electrical ratings. Rechercher:
- UL label or manufacturer data plate — usually on the back or bottom of the appliance
- Watts (W) — if listed directly, this is the running wattage
- Ampères (UN) and Volts (V) — multiply them: Watts = Amps × Volts
- VA (volt-amperes) — for devices with motors or power supplies, VA × facteur de puissance = Watts. Utiliser 0.8 Facteur de puissance if the device has a motor, 1.0 for resistive loads
Example Calculations from Nameplate Data
| Appareil | Nameplate Says | Calcul | Watts courants |
|---|---|---|---|
| Réfrigérateur | 6.5A @ 115V | 6.5 × 115 × 0.8 PF | 598W |
| Microwave | 1,200W input | Direct reading | 1,200W |
| Space heater | 12.5A @ 120V | 12.5 × 120 × 1.0 PF | 1,500W |
| Fenêtre AC | 8.5A @ 115V | 8.5 × 115 × 0.8 PF | 782W |
| Ceiling fan | 0.75A @ 120V | 0.75 × 120 × 0.8 PF | 72W |
Méthode 2: Use a Kill-A-Watt Meter ($25-40)
Plug the meter into the wall, then plug the appliance into the meter. It displays real-time watts, volts, amps, and cumulative kWh. This is the only way to measure actual starting surge — watch the display for the 1-3 second spike when a motor starts.
What You’ll discover with a watt meter
- Actual running watts are often 30-60% lower than nameplate ratings (safety margins)
- Starting surge on compressors is 3-6× running watts for 1-3 secondes
- Some devices draw power even when “off” (phantom loads: 3-15W each)
Méthode 3: Check the Owner’s Manual or Manufacturer Website
Rechercher “[marque] [modèle] wattage specifications” or check the manual’s specifications page. Manufacturers often list both running and starting watts, which saves you from estimating surge factors.
Méthode 4: Use Reference Tables (Least Accurate)
When you can’t access the appliance (par ex., sizing before purchase), use reference tables. These give typical ranges — always use the high end of the range for generator sizing.
| Catégorie | Gamme typique | Surge Factor | Conseil de dimensionnement |
|---|---|---|---|
| Éclairage (DIRIGÉ) | 5-15W per bulb | 1× | Simply count bulbs × 10W |
| Electronics (TV, laptop, router) | 50-300W each | 1× | Add 200W total for entertainment |
| Motor-driven (réfrigérateur, pompe, fan) | 200-1,500W | 3-6× | Surge is the critical number |
| Chauffage (space heater, chauffe-eau) | 1,000-4,500W | 1× | Resistive — no surge |
| Cooking (micro-ondes, range) | 1,000-5,000W | 1-1.2× | Microwave input > cooking power |
Don’t Forget These Often-Missed Loads
- Sump pump — critical in flood-prone areas; 800W en cours d'exécution / 2,000W commençant
- Garage door opener — 600W running / 1,800W commençant (½ HP motor)
- Well pump — often the single largest surge load in a Maison
- Sump pump — may run continuously during storms when you need your generator most
- EV charger — Level 2 draws 7,200W; most Générateurs cannot support this
Astuce Huaquan: The most accurate generator sizing starts with a Kill-A-Watt meter and 15 minutes of measurements. For large installations, Puissance Huaquan provides free professional load surveys.
