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human
LED Lighting: If I am installing recessed lighting, is it more efficient to have 4 lights at 50% dim or 2 lights at 100%?

I am remodeling my house, and am going to install some LED lights.  I can see that there is an option to dim the lights with the accompanied driver.

Is it better to get 4 lights and run at a lower setting, or to get 2 lights and run at full power?  For this example I used 4@50% or 2@100% to get an idea.

I assume the driver has an energy usage that is partly independent of the setting, which means I may use more energy at 4@50%, but I also know some relationships of energy usage are squared and so maybe it could be less.

Thanks!
gpt
LED lighting has a different luminous efficacy curve than incandescent. In the case of incandescent lamps with equal design features, two lamps at full power will generally outperform four lamps at 50% power in terms of luminous efficacy. **This is not necessarily true with LED.**

In general, you will lose some power in the dimming circuit and this is not good from an efficiency standpoint. How the particular lamps you use operate will ultimately determine the best course of action. It depends on the particular LED and the drive current. (Overdriven LEDs tend to be less efficient and tend to not last as long.)

Your lighting system should come with a datasheet that shows a lumens vs. power graph. That will tell you the best course of action.

There are other benefits to more lamps at reduced power output: The LEDs themselves are likely to last longer. Upwards of 100k hours is possible for moderately driven LEDs. Also, with more light sources it may be possible to design a lighting system that produces a more even light. Also you could selectively switch them for task lighting.

There's a saying in engineering: *When in doubt, consult the datasheet.*