Too Much Light

• The most common cause of dimmer overheating is installing bulbs of too high a wattage. The total wattage for all the bulbs you are trying to dim shouldn't exceed 90 percent of the rating for your dimmer switch. If it does, the switch will overheat, perhaps dangerously so. Remove some bulbs, reduce their wattage, or install a dimmer with a higher rating.
  
  

Improper Installation

• Dimmer switches are rated for a certain wattage. If two or more dimmers are installed side by side, the installer must lower that wattage rating for each additional dimmer and plan the circuits accordingly. Also make sure no one has tampered with the heat sinks, those metal plates installed on the dimmers by the manufacturer to help dissipate excess heat.
  
  

Normal Operation

• Modern dimmer switches are highly efficient. Only about 2 percent of the power running through them is converted into heat. That's much less than older models, but even if everything is installed and being used properly, a dimmer switch will still feel warm to the touch. If yours is hot enough to burn you or smells funny, something serious may be wrong.