The Lutron "Maestro C•L" dimmer has different wattage ratings depending on the type(s) of bulbs being controlled. Its an electronic dimmer.

Specifically, when 100% incandescent or halogen it can handle 600 W, but when 100% LED or CFL only 150 W, with a gradual variation between these extremes for mixed bulb types.

Info from the specification sheet:

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(The wattage capability also varies based on the # of "sides removed" though I can't see in the docs what that means.)

Source: http://www.lutron.com/TechnicalDocumentLibrary/369613a.pdf

What is the reason for the degraded wattage capability when running LED bulbs?

And is this variation in wattage capability typical of this sort of dimmer?


1 Answer 1


Since dimmable LEDs don’t use active PFC for cost reasons, the peak/average current is much higher, called the crest factor, so conduction losses demand this de-rating of power limits in a Triac dimmer.

The last page gives examples of multiple dimmers on the side and why that causes further derating by how far “removed” from the load to line a configuration is possible. “Removed” here means shifted away from power input by cascaded dimmers.

  • 1
    \$\begingroup\$ This answer brought to you by the terms Power Factor and VA. PFC = Power Factor Correction. Power factor being a ratio: the difference between the power a pure resistive load would use at those same instantaneous peak amps, and what the load actually draws. Because you must generate and deliver the entire sine wave, even if only part is used. \$\endgroup\$ Dec 16, 2021 at 19:54
  • \$\begingroup\$ @Harper-ReinstateMonica yes but it is the crest factor of peak capacitive current that has much higher peak power than average RMS power that it is derated. Similar to derating on inductive motors. But yes if they did have active PFC then derating would not be required. TY for adding definition for others \$\endgroup\$ Dec 16, 2021 at 20:05
  • \$\begingroup\$ We occasionally link this answer from the DIY forum (when people ask about this), so I'd appreciate if you could expand terms and make it a bit more novice-accessible. \$\endgroup\$ Dec 16, 2021 at 20:25
  • \$\begingroup\$ @Harper-ReinstateMonica perhaps you can get the programmers to put in www.wikiwand.com tool so that key technical words can be linked instead of just add highlight> add URL > search > copy > paste > return for every word that newbies can do on their own too. Please ASAP and Thank you. \$\endgroup\$ Dec 16, 2021 at 21:51
  • \$\begingroup\$ @TonyStewartEE75 It is rather hard to get StackExchange programming changes done, especially if they are relatively specific to particular small sites (as compared to the primary StackOverflow site). On Codidact we have done something similar to link Sefaria to biblical & other references on the Judaism site (similar to Mi Yodea on SE). Not hard to do, but I think with SE it would be a "userscript" so the people who need them most would be least likely to see the links. \$\endgroup\$ Dec 17, 2021 at 0:27

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