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I have installed a 15m long flexible solid LED light strip in my living room (precise model). It works well, but the only problem is that it is far too bright. I was expecting some nice "mood lighting" but instead it fully illuminates the room.

I thought I could just install a wall dimmer switch (there are some nearby wires to which I can connect them, but I didn't realize that LEDs are "dimmable" and "non-dimmable" before I installed this one.

I was doing some research and learned that LED light strips need an adapter to properly interpret a wall dimmer switch. The light strip I have installed does in fact have an adapter attached to its normal power cable (says 220-240V, 50-60Hz on it) but I am not sure if it is the correct one. If I cut the power cord after the adapter and then connect it to the nearby wires, will it be able to dim from a dimmer switch? (I have confirmed which outlet the nearby wires are connected to)

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  • Wonder if you can put some type of a shade on/ in front of it. Maybe something like a short shear curtain.
    – crip659
    Oct 3, 2022 at 14:44
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    No, you cannot just cut the adapter out and directly wire to a dimmer, this will destroy your LED strip! I would insert a PWM module between the adapter and the LED strip to provide dimming capability.
    – Glen Yates
    Oct 3, 2022 at 16:06
  • Pick somewhere that a lot of light would be good (shop/garage?) - move this one there. Buy a dimmable one for here.
    – Ecnerwal
    Oct 3, 2022 at 16:43
  • You can buy "ND filter gel" which will dim any light source without changing its colour at all, but it might be simpler, if not cheaper, to just get dimmable strip & wire in a dimmer.
    – Tetsujin
    Oct 3, 2022 at 18:26
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    @Glen it's not a 12V strip. The strip uses 230V internally. And it's cheap Chinese. "what could possibly go wrong" Oct 3, 2022 at 19:38

3 Answers 3

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15 meters of any light source is going to be very bright no matter how dim each individual lighting element is. Even if each individual LED is only putting out 1 lumen, how many individual LEDs are there in your strip? That's the minimum you'll get no matter what. You simply have too much light production capability.

I found some dimmable LED bulbs for my kitchen that produce up to 800 lumen each. I put 3 in and even with only one bulb on at its lowest setting it's far too bright for my tastes. Either I need new bulbs or I need to learn to live with it.

Additionally, I see nothing in that listing that indicates that these are dimmable bulbs. You can provide them with less power, but they'll either not light at all, they'll flicker, or they'll burn out quickly.

TL;DR:

NO, you cannot just cut the cord and attach these to a dimmer of some sort to make them produce less light.

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  • I bought a cheap dimmer socket adapter to test if the strip could be dimmed. It worked. I decided to just take the risk and buy an LED wall dimmer switch, install it, and then I just cut off the plug cord right before the plug and connected it to the wires in the ceiling. It works totally fine.
    – wfgeo
    Oct 8, 2022 at 12:20
  • actually they emit 1.5 to 2 lumens per led. But if you run them at 1% duty cycle, you only get 27 lumens over the length ( 15m*120led/m*1.5lum/led*0.01duty), which is about a night light's worth. Without long leads, a 1/255 duty cycle is very do-able, yielding a floor of around 10 lumens. That said, OP would need a high-voltage high-frequency LED driver for his strips, which is not a typical piece of kit. At 50Hz, a triac dimmer will only let you do 2% min, but that's still a just "bright" night light at 54 lumens...
    – dandavis
    Oct 9, 2022 at 22:54
  • @wfgeo I'm not entirely sure how you've wired this, but it doesn't sound like it meets NEC. You can't have cordage (i.e. extension cord) buried in a wall, and you can't have cable (i.e. NM-B or "Romex") used outside a wall. Somehow, somewhere, it sounds like you've got one or the other. You'll probably be fine, but if you're not, you might find that the insurance company decides to deny your claim for illegal wiring...
    – FreeMan
    Oct 10, 2022 at 0:13
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This thing is terrifying. It's cheap Cheese shovelware straight of Alibaba, which means there's nothing safe about it because it uses 230V internal to the strip. I'm generally willing to trust low-voltage stuff, but putting AC mains on those LED strips is bonkers.

Never buy electrical gear on Amazon, for the same reason you wouldn't buy electrical gear on eBay. Amazon opened up their store to 3rd party sellers, and so most gear on Amazon is exactly the same crud as found on eBay.

It is an "LED strip" of the style one is used to seeing in 12V or 24V (which allow the strip to be cut every 50mm or 100mm respectively)... however, this one is 230V internally. Really. Note how it can only be cut every 1 metre.

That is because these LED strips are constructed as 3 LEDs and a resistor every 50mm, and that unit takes 12 volts. Thus, 12 volt strips get cut intervals every 50mm. 24 volt strips get cut intervals every 100mm.

The lump in the cord is far too small to be a low voltage power supply. It may be a bare diode rectifier which is even scarier because now we're dealing with DC, which has much more dangerous characteristics.

Since the product is not safety-rated for sale in your country, you should feel absolutely privileged to send it back angrily.

I cannot advise on how to dim this, because a) continuing to use it would be insane, and b) I am really not sure which internal technology they are using. It is definitely incompatible with any of the dimmers used in normal 12V or 24V LED strips, since those are expecting 24 volts at most.

My advice would to re-do this with normal 12-volt or 24-volt LED strips, which will allow you to use normal 12-24 volt LED-strip dimmers which use PWM technology. That is an excellent dimming tech that will do what you want.

With 12 volt low voltage stuff, safety is far less of a concern, so dodgy sources like eBay/Amazon are not as great a risk.

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  • Are you sure about all of this? Isn't the thing on the cable itself the 12V adapter? (On the first picture in the top right, the one other than the switch.
    – wfgeo
    Oct 8, 2022 at 12:32
  • @wfgeo yes, the 1m cut interval gives it away. Normally cut intervals are 50mm for 12V. The lump on the cord is too small to be a power supply. Don't take my word for it, measure it. Oct 9, 2022 at 3:57
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If you go through the information given in your link it is DC, that is given when they tell you to reverse the connection to the strip if it does not work. Because of the way LEDs work consider placing maybe a 48V transformer connected in bucking mode in the AC feed, it should dim it quite a bit. However the first thing and probably the most cost effective, would be is to measure the voltage to the LEDs and if it is maybe 30VDC or less you can get a very inexpensive PWM module that will you to adjust the brightness. You can get them from the same place you got the LED strips. They have some that are 12-24V for less then $15, they work great. They simply have basically a 555 and a MOSFET inside. I got mine on aliexpress for much less. Mine do not get warm with about 15A LED load.

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