When sizing an RV inverter, most people focus on the running wattage listed on their appliances and add everything up. But inverters fail because of surge draw — the brief spike of power many devices need when starting up. A microwave labeled as 1000 watts might need 1800 watts for the first few seconds, and that surge is what trips your inverter or blows fuses.
This is especially problematic with motorized appliances. Coffee makers, blenders, vacuum cleaners, and anything with a compressor can draw double their rated power during startup. Hair dryers are notorious for this — a 1200-watt dryer might surge to 2000 watts, which explains why they frequently trip breakers even when you think you have adequate power available.
The practical impact: if you want to run a 1000-watt microwave reliably, you need at least a 2000-watt inverter, not the 1500-watt unit that seems adequate based on the label. Pure sine wave inverters handle surge better than modified sine wave, but both need to be sized for peak demand, not average demand.
Here’s what experienced boondockers do: they test each major appliance with a kill-a-watt meter or similar device to see actual startup draw, not just running draw. This prevents the frustrating situation where your inverter works fine with lights and phone chargers but shuts down the moment you try to make coffee. Some appliances have “soft start” features that reduce surge — worth looking for if you’re building a system around limited inverter capacity.