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High Power LED Under Cabinet Lighting DIY - Great looking and BRIGHT @ only 23w!

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First off, let me explain that "High Power LEDs" should probably read "High Intensity LEDs".  By my calculations this whole setup uses about 23w of electricity.

Anyways, after getting new kitchen cabinets and getting a nice shiny granite counter top installed it was time to get some truly impressive under-cabinet lights that would complement the design I was aiming for while being wonderfully functional as well.

This instructable is going to show you how I created my DIY under cabinet lighting for less than $120 and yet achieved professional results better than every commercially available system I was able to see in person.

This is a true DIY system, not a guide on how to install a commercially available system.  So before starting, know that while I think this should be considered an "easy" project some basic skills are required such as being comfortable working around electricity (which can be dangerous!) and you also need to know how to solder.  Other than that though there aren't any special skills or tools required.

Thanks for reading, now on to the good stuff!
-Aaron

Also, a special thanks to my dad, who helped me with this project.
 
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Step 1: Design the system

Picture of Design the system
IMG_1259.JPG
Fair warning, this is the longest step! This is basically my thought process on designing the setup.  Skip this step to see the materials list and build instructions...

Under cabinet lights can make or break a kitchen.  They can add instant and real appeal to a space, but they have to meet certain criteria.  They have to be effective task lights.  They have to add the right "ambiance". They have to match up with your current lighting scheme, and finally they have to work well and last a long time (due to the fact that installing lights under your cabinets often requires some modifications - it's a pain to have to re-do it or constantly fix things!).

In designing my setup I was able to cross off the typical halogen puck lights almost immediately. They are bright and beautiful, but they have many weaknesses.  They are too big, too hot, and as a result they don't last very long (plastic cracks, glass falls out, and bulbs burn out quickly).  Probably the worst part about them is the horrible amount of wire needed to hook them up!

For me the obvious choice was LED.

Scouring the internet for project ideas turned up very few truly "DIY" LED options.  Most DIY projects were related to installing a commercial product.  I checked with local lighting stores and home improvement stores and found solutions that were either woefully inadequate or ridiculously expensive.  I found some modular systems that came close to what I was envisioning, but I quickly came to the conclusion that I could build it to look and perform better, for cheaper.

I have some basic LED knowledge from building a light for my reef aquarium.  Oddly enough I think that the reefing hobby has given a monumental push to high-power LED lighting in recent years. I've also messed around with some normal 5mm LEDs and such while experimenting with my arduino and other electronic gadgets.  I am still by no means an expert...

With LEDs you need to keep a few things in mind. Namely, LED type & placement, power, thermal management, and color.

LED Type & Placement:
LED under cabinet lighting can be divided into 2 groups, strip lights and individual lights.  The strip lights typically provide more even light throughout the surface (like a fluorescent bulb), while individual, or "puck" lights offer a more dramatic lighting source with varying intensities that start out really high when you're right under the light fading out as you move further away from the light.

I went through several designs for both and found that typically strip lights use smaller SMD LEDs mounted on a long, thin PCB or flex tape.  These are nice, low-profile options, however, I found that they aren't nearly as intense as single lights. If I were to do a strip light application using LEDs I would use 2 rows to get enough light.  Using 2 rows increased the cost significantly though.

I ended up settling on high power 3W LEDs, just like what are commonly used in reef lighting, specifically the CREE XT-E LED.  They are very versatile, they put out a lot of light and there are several drivers that are perfect for powering this type of LED, especially if you want to get fancy with dimming (many support 0-10v dimming as well as PWM dimming). The important part is getting the spacing right to avoid shadows and to have the right thermal setup.  I experimented quite a bit and decided that the best light was when the LEDs were spaced evenly apart under the cabinets about 12" on center. More LEDs than that and I would probably be wasting efficiency (because I would end up dimming it most of the time). Less LEDs than that I may be sacrificing some of the practical task lighting.

Power:
For power I went with a dimmable constant current driver.  The LEDs I used have a 3v forward voltage @ 700mA, to wire them in series you basically just add up the total forward voltage (I used 11 LEDs so 3x11=33v) and make sure the driver you buy supports that voltage at whatever current you want.  700mA is a good amount of current because it has a good efficiency but the LEDs won't get as hot. The LEDs are rated to much higher than that, and while they do get brighter the more current you feed them, they get a lot hotter and the efficiency drops as well.  I decided to use a reliable inventronics 40W driver

A nice thing about this driver (and some others too) is that it's scalable.  According to the datasheet @ 700mA it outputs a minimum of 18v and a maximum of 54v.  This means that if you have 3v LEDs you can safely use a minimum of 6 LEDs and a maximum of 17 LEDs or so (you want a little wiggle room at the top range).   By using the spacing I described above you could light anywhere from 6 to 17 linear feet of counter top!  If you still need more LEDs than that, don't worry.  Just look for a constant current driver that supports the voltage range you require.  Just take your LED voltage at the current you want and multiply it by the # of LEDs you want to get the voltage requirement.  Meanwell, Inventronics, and Phillips Xitanium are just a few.  A LED driver takes your homes 120v power and converts it into DC power for the LEDs. 


Thermal Management:
Thermal management is going to be important in a high power LED array, and while I thought about just using aluminum channel or flat bar from home depot I ended up with a much more elegant (and more effective) solution that didn't cost any more. I spent a lot of time searching for heatsinks and while I found a bunch, they mostly came from China or they were too tall for my application (I only have 3/4" under my cabinets).  I ended up deciding to use a really nifty looking circular heatsink that was designed to be used with LEDs.  A typical CPU style heatsink wouldn't work in this application because the heatsink has to be up against wood, so this design is perfect to get enough airflow. Best of all, you can get this heatsink in several different heights, and no drilling is required to mount the LED or the heatsink to the underside of the cabinet!  It's the Ohmite model SA-LED-113E

Color:
Let's not forget about color!  This is probably the most important...  I would deal with those crappy halogen pucks before I chose a fluorescent light for this exact reason.  The color temperature is going to dictate the mood of the lighting as well as how good or bad things look underneath them.  Imagine you're preparing some food on the counter and the broccoli looks brown...  You're not going to want to eat that. Now imaging looking at broccoli that looks clean and bright green, as if you just harvested it. That's the power of selecting the right color light.

Warm white is the color most often chosen, and the color I desired for my kitchen. The kelvin range for "warm white" is between 2700k and 3500k.  Warm white has the highest CRI (color rendering index) and IMO things look most true to life under this color lighting.  I decided to stay on the slightly cooler end of the spectrum though, since I don't have many windows.  I chose 3250k LEDs which I found correlate quite well to the "soft white" compact fluorescent bulbs that I use in the ceiling lights.  On that note you need to try to match the color of your under cabinet lights to the rest of the lights in your kitchen or it will look funny. So you would either need to find the right color LEDs or you'll need to change out the other lights in your kitchen.

So those are essentially the principles I used to design the system.  Depending on your space you may need to tweak some things, but I what I put together has worked out really REALLY well in my opinion and for my purposes.

Sorry that was a lot of reading, but it's important to spend the time to do it right and enjoy the results! I'm not going to upload all of my sketches, but the excel diagram is what I ultimately ended up with (1 square is 6 inches):
151041 month ago

Really great looking outcome to your project. I am quite inexperienced at working with LEDs but I am thinking of giving it a shot. The halogens are giving me the blues, replacing every week or two.

I do have one question. Does the circuit require a resistor for the LEDs?

Thanks,

GeorgeH

nidecker1 month ago

Hi there,

Thank you for the amazing tutorial - this is going to save me a lot of time and money for the undermount lighting.

I have a question regarding the dimmer that you recommend. Can I use the Leviton 6674-POW SureSlide http://www.amazon.com/gp/product/B0076HPM8A/ref=ox... rather than the dimmer you suggested? I'm thinking (and I am by no means an electrician) that I would run power to the dimmer, then to the transformer but if you say "no" then I'll definitely go your route.

Thanks again - your lights look amazing (and you have almost the exact same kitchen as me!

Best,

Sean T.

cslynch3 months ago

I just wanted to say thanks for the great instructable. I just got done with a 14 light install and it looks great. The only thing I would add is an on-off switch for the AC circuit. I pulled 14/2 romex off of an existing outlet and ran a new AC plug on top of my cabinets. I then replaced the original outlet with a combo AC plug/Switch style. The new outlet runs off of the switched side so I can shut the LED driver off. I had to do this because the driver only dims to around 10% with the potentiometer dimmed all the way. The lights wouldn't shut off without a switch.

Nice work and great write-up!

yosh8771 year ago
Did you ever come up with a good solution for diffusers?
ajmckay (author)  yosh8774 months ago
Believe it or not I'm still not using diffusers. Turns out the only ones who see the glare are my kids since they're shorter than the cabinets. I tried a few versions of diffused plexi glass but I didn't really like the look or the bulk that the additional pieces added.

Ultimately, I've accepted the face that there will be some glare if you're low enough. If you have a situation where the angle is very slight (for example sitting at the dinner table more than 10ft away) then I found that small rings of 1" or 3/4" PVC pipe, maybe 5-10mm tall were extremely effective in those situations. You still get glare if you're right under the countertop, but the glare goes away once you are 5-10ft away from the cabinets and at sitting height.
ocpr20104 months ago
Thank you for the well explained instructions. I did like it that much that had tried it. I installed everything as the instructions except that I didn’t install the dimmer. Everything looks great. But don't light up. Could it be that had to have a dimmer in order to work? My set up is just like your but with 12 LED instead of 11.
ajmckay (author)  ocpr20104 months ago
Hi there, sorry for the delayed response. Did you use the same LED driver and the same # of LEDs? I don't recall exactly what to do if you don't use a dimmer, but it looks like they moved the data sheet, which is now located here: http://www.inventronics-co.com/upload/EUC-042SxxxDS%28PS%29_2013041009043160911.PDF

I would start with making sure that your LEDs are wired in the correct polarity first. The driver is smart enough that it won't turn on if the LEDs are wired wrong - this is an excellent safety feature. If they are all wired correctly, then we may have to do some internet searches to verify but I'm almost positive you can use the driver without a dimmer. Don't just start touching wires together though. Worst case, install a dimmer (Potentiometer) for $5 or less from Radio Shack and hide it away with the LED driver above the cabinets.
bfarm1 year ago
Are you sharing line voltage with low voltage (dimmer potentiometer) in the same
3 gang box? Suggest that dimmer be kept separate as to avoid the electric code violation. Which back splash tile did you go with?
bfarm bfarm1 year ago
Article 725 in general discusses low voltage circuits. Not sure if your power supply is a class 2, as most commonly are (class 2 is a power limited designation). 725-54 requires separation of conductors from power or lighting circuits. If the power supply isn't class 2, then the wiring is covered under article 300 and you can't have open wire nut splices and the like.


Not that you are going to necessarily burn the house down but you would most likely fail an electrical inspection if noticed. The kitchen looks all pro so the work should be legal. Suggest the dimmer be mounted in some small housing under the cabinets.
ajmckay (author)  bfarm1 year ago
Thanks for the useful information. I'm not sure where I'll put mine, but in the meantime I edited that step in the instructable.
ajmckay (author)  bfarm1 year ago
Thanks for the comment bfarm. Can you reference the specific NEC article? I would be happy to include it in the instructable (not everyone reads the comments). I've thought about this before, and while I can't say specifically what the NEC states about this, I'll update the guide with whatever information is appropriate.
kinderdm1 year ago
I am really excited to give this instructable a try. I was just looking for under cabinet lighting to replace the halogens we have now that always burn out and was not very happy with the options i found online for led. I finally made the decision to DIY my own approach. I am not as knowledgeable though and was not confident in designing my own. Your instructable comes at the perfect time and I cant wait to get a chance to have a go at my own setup. Thanks for the great documentation.
ajmckay (author)  kinderdm1 year ago
Thank you for the comment! I was pretty disappointed in the commercial offerings for LED as well. I think I put this in the instructions, but remember that using the driver I listed you could expand or contract the # of LEDs used to a minimum of 6 LEDs up to a maximum of 17 I believe (as long as they're 3v LEDs like the ones I used). Good luck!
Yeah, that's perfect for what I need then. I'm looking at about 10 led's or so for my setup. Once again thanks for the great instructable.
Great Instructable with nice pictures and links to materials. Some of that stuff can be so hard to find.
ajmckay (author)  stevemoseley1 year ago
Thanks for the comment. You're right that it took several weeks to find the right products within my budget!
rohit445241 year ago
chain saw can cut ur head beware see for more details
ajmckay (author)  rohit445241 year ago
(removed by author or community request)
www.instructables.com/id/ChainSaw-Ur-Head-PhotoShop-CS5/

:) :D
I am so excited about this project! Being a brand new DYI'er I will not be attempting it myself, however....I plan to "sweet talk" someone I know into helping me!!! Can't wait, Thanks!!
ajmckay (author)  yogagoddess081 year ago
Thanks for the comment! You could easily do most of the steps including prepping the wire and the heatsinks and then just get some help with soldering it all together. Note that there are youtube videos on how to solder these LEDs. Good luck!
Looks great, you can really see the difference before and after the light installation.
ajmckay (author)  mikeasaurus1 year ago
Thank you Mike for the comment.

It's really unbelievable how much better it looks. It's hard to tell in the photos but the recessed overhead lighting is plenty bright, even without the under cabinet lights. The task lighting that these LEDs provide, however, is almost beyond what my initial expectation was. It makes food look much better and greatly enhances the beauty of the granite counter top. At night the under cabinet lights make the kitchen a much more relaxing place to be with the overhead lights off and just these lights on, dimmed.

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