The Intermatic T104-20 40A Electric Water Heater Timer Switch DPST provides a convenient external override switch. Utilities in many areas of the country offer two electric rates for residential or commercial customers. One rate has the regular daytime electrical rate, the other is 'off peak' rate. The off peak rate provides customers with 'lower-priced' electricity during the nighttime and weekend periods. This timer switch allows the customer to shift electricity use into these off-peak time periods in an attempt to save utility costs.