Common dimmer wattage ratings are 150 watts, 300 watts, 600 watts and 1000 watts. 150 watt rated dimmers are usually for a single bulb. Wattage rating is usually on a sticker on the light fixture.
Dimmer wattage calculation example:
While older rheostat type dimmers do not, modern dimmers do save energy when dimming lights. Dimming lights also extend the life of incandescent light bulbs.
It is normal for a dimmer to feel warm especially if the lighting load is close to the dimmer rating. A higher wattage dimmer may need to be installed if the following apply:
Dimmer switches usually have two black wires protruding from the back of the switch. One wire connects to the light(s), the other connects to line. The green wire connects to ground. If a dimmer has one black wire and one red wire, usually the black wire connects to line and red wire to the load.
Ground connection is not shown.
Dimmer switches are used to control lighting level and can save energy. Dimmers work by limiting the voltage that goes to a lighting load. Dimmers work very well with incandescent bulbs because of a wide dimming range.
For other types of bulbs including CFLs, halogen, and LEDs, check to see that they are “dimmable” on the bulb package. Dimmable CFLs are usually more expensive and have a limited dimming range, mostly at the dim end.
Dimmer Switch Usage