A burning light bulb uses a certain amount of electricity, which is measured in watts. By lowering the wattage with a special switch, consumers can manage the bulb's electrical consumption. Dimmers come with a dial or a slide bar, which allows homeowners to adjust the wattage and thus the amount of illumination. Just how much energy dimmer switches save depends on many factors, including how much and how long a person dims the light, and the type of light bulbs in the fixture. Dimmers save the most money in rooms where wattage is high, such as the bathroom, kitchen and dining room [source: Oldroyed].