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Some of my LED GU10s (dimmable) produce too much of light and I'd like to reduce it. I'd like to use on/off switch on those GU10s with permanently reduced light. How it could be done and what kind of components I should use?

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  • Add a series resistor.
    – Solar Mike
    Commented May 2, 2020 at 19:15
  • What ratings do your current LED 'bulbs' have - either in lumens or 'equivalent watts'? You may be able to find some other GU10 LEDs with a lower rating and simply swap them out.
    – brhans
    Commented May 2, 2020 at 21:44
  • I use Tungsram 350 lm high CRI GU10s, but unfortunately there are no lower rating models and I do not want to mix with other manufacturers. I would opt to around to ~200-250 lm
    – Domas
    Commented May 2, 2020 at 21:48

4 Answers 4

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They're called cinematic gels

They are just a gray filter that you put over the LED. You can also get color-tinted, if you are trying to white-balance with other lights.

But a light one, and if you need more dimming, add layers.

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You might consider a dimmer switch that has a "slider" that is separated from the switch. This would be completely code legal, give you the convenience of setting the dimming level once and then just use the switch. You'd also have the flexibility to adjust it easily if your needs change. Just make sure whatever dimmer you choose is compatible with your LEDs. dimmer with slider

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Besides series resistors and gels/foils a series X2 capacitor could also help without wasting energy and extending the mean time between failures of the LED bulbs. These mostly rectangular yellow capacitors can be easily harvested from junk electronics at home or from the next recycling yard and can be located near where the power cable enters the junk device. Trying some values around 100 to 1000nF like 220nF or 330nF should dim the bulbs. The lower the value, the lower the brightness. These X2 capacities are very safe. In case of using series resistors they should be also explicitly suited for this application (flameproofed, voltageproofed). Of course all safety requirements must be met, one important is that the series elements must be inside an insulating housing that can only be opened with tools. Both ends of the series resistor or capacitor can have the full line voltage.

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    Xeeka, you must be pretty clever when it comes to electronics, but most people are not. For a newbie to follow your advice could be quite dangerous. And I'm pretty sure most of what you are suggesting isn't code legal. Let's keep it safe out there! Commented May 2, 2020 at 20:30
  • @GeorgeAnderson Of course safety first! My answers are often focused on safety - and energy saving. One big part of my motivation to answer here was the bare very short comment to "add a series resistor". So I added the alternate method with an X2 cap (which in general is more safe since no real power/heat is involved) and clearly mentioned the safety aspects. In general my answers always take the safety into account - regarding others' statements and even where local codes seem to have important insufficiencies.
    – xeeka
    Commented May 2, 2020 at 20:59
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    Can you link any capacitors that are UL-Listed (RU-Recognized won't cut it) and whose instructions say to use them directly in mains wiring? That is a prerequisite to using in mains wiring NEC 110.2 and 110.3(B). Only such product I'm aware of, the LUT-MLC, but that's not listed for series use. Commented May 2, 2020 at 21:37
  • @Harper-ReinstateMonica The class X2 is already indicating that qualification for mains usage - and is printed on the cap. Here you may find those safety capacitors with qualifications like ENEC, UL, cUL, CQC: uk.farnell.com/c/passive-components/capacitors/film-capacitors/… The series usage is not explicitly mentioned - most likely because the qualification for parallel use would automatically cover the series use, if the device is short cut or has a big insurge current or has a very big wattage thus low resistance.
    – xeeka
    Commented May 2, 2020 at 21:54
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    Yeah that's the difference between UL the company, and UL the listing. Contrast that cap with the LUT-MLC, which has a plainly visible c-UL-us mark and whose UL-approved docs plainly state what it is to be used for, and how to install it. You must install it according to instructions. Further, note the device provides terminations compatible with NEC 3.xx wiring methods. Commented May 2, 2020 at 23:10
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Use an inline dimmer, set it to the level that you want, than forget about it.

Here is one that I've used https://www.amazon.com/Low-profile-Inline-Controller-Dimmer-Switch/dp/B00KAFESOE

Another https://www.amazon.com/Dewenwils-Plug-Dimmer-Bulb-HPID02B/dp/B07CZXLNWL

more https://www.1000bulbs.com/category/in-line-lamp-dimmer-switch/

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