Resistive Loads vs. Motor Loads: Why Some Appliances Need Way More Starting Power
A resistive load (a heating element, like a toaster or space heater) draws essentially the same wattage the instant it turns on as it does while running, since there's no mechanical motor to overcome — a motor or compressor load (a refrigerator, pump, or air conditioner), by contrast, briefly needs extra electrical force to overcome the physical inertia of getting its motor spinning from a standstill, which is exactly what produces the startup surge that resistive appliances simply don't have.
This is the underlying physics behind why the surge-watts consideration only matters for some appliances and not others.
Why resistive loads have no real surge
A heating element's electrical resistance is essentially constant whether it just switched on or has been running for an hour, so the current (and therefore wattage) it draws stays essentially flat throughout — this is why toasters, kettles, space heaters, and incandescent bulbs are treated as having no meaningful surge in sizing calculations.
Why motor loads inherently need that extra initial push
An electric motor at a standstill has far higher initial resistance to overcome than once it's spinning at operating speed, so it briefly draws much more current (and wattage) in that first fraction of a second — the exact same physical principle behind why it takes more effort to start pushing a heavy object from a stop than to keep it moving once it's already sliding.