Dimming - What is the importance of the lamp wattage for a dimmer?

Every dimmer has a minimal required power and a maximum permissible power. This is expressed in watts (W), for loads that respond in a resistive way, or volt-ampere (VA) for inductive and capacitive loads.

The overall load of a lighting circuit is calculated by adding together the power values of all the light sources. This value must be between the minimum and maximum load thresholds.

When the electric load is lower than the minimal power threshold, the light source may flicker or not ignite at all. When the load is greater than the maximum power threshold, heat will be generated and a dimmer with a thermal protection capability may automatically switch off the lighting circuit.

Note:

• The maximum power load of a dimmer for LED lamps is usually 200 watts. However, check the dimmer manual for the right maximum power threshold.
• The maximum power threshold reduces when the ambient temperature increases above 35°C. The maximum permissible power load drops 10% for every 5°C temperature rise.
• When modular dimmers are mounted next to one another inside the electrical cabinet, you may only connect 80% of the maximum permissible power load. A minimal distance of 20 mm is required in order to utilise the maximum power. Also ensure that the electrical cabinet is sufficiently ventilated. Electrical cabinets are usually closed, which allows the temperature to rise.
• With flush-mounting dimmers, the maximum permissible power drops when:
  • The flush-mounting dimmer controls 230V AC halogen lamps. In this case decrease the maximum electric load by 20%.
  • Multiple flush-mounting dimmers are installed in wall-boxes next to one another. In this case decrease the maximum electric load by 25%.
  • The flush-mounting dimmer is installed inside an insulated wall, which is not stone (plaster or wood). In this case decrease the maximum electric load by 15%.