A typical 'eco' cycle might take about 90 minutes. The dishwasher might have a rated peak load of 10A/1200W, but you can't just multiply that by 1.5 hours. The

A typical 'eco' cycle might take about 90 minutes. The dishwasher might have a rated peak load of 10A/1200W, but you can't just multiply that by 1.5 hours. The peak power is for the resistive heater, which runs for several minutes at the start and intermittently throughout the cycle, as heat is lost through the insulated enclosure and out with the periodically drained water. But most of the duration is spent pulsing the small 1.3A/160W/0.2 HP circulation pump. It works out to a little less than 1 kWh for the full cycle. Like my high-efficiency front-loading clothes washer, it ostensibly reduces energy and water use by running a small, efficient motor for a long time instead of a high-power motor with lots of water for a short time. A commercial dishwasher might have a 30 amp, 220V heater, and a 3 horsepower 220V motor. The heater draws 6.6 kW for 4 minutes to warm up the machine before you can run the first load, or 0.4 kWh, and the motor runs for 90 seconds at 2.3 kW, so the total power requirement is actually less than the 'Energy Star' consumer unit at 0.5 kW/cycle!