Under cabinet LED lighting

[Neurorad]

I had an electrician run my line voltage and LV cables, for my kitchen remodel. It's all behind the drywall.

I used the WAC LED pucks on a tip from a CT and AVS member who is also an electrician and integrator. He said they dim well with RA2, and he was right.

I went with the Task Sempria under-cabinet LED system because the kitchen designer had spec'd them previously, and the installer was familiar with their modular system. I'm switching the UC LEDs with RA2, not dimming.

Task also makes an angled under cabinet outlet strip, really well designed and clean. Can also accomodate any Decora inserts, good for TV.

 

[JimS]

Well the ebay stuff MIGHT be fine but I don't see any specs - did you?
 

I don't see any UL markings on the ebay item and while I see the 3M marking on the adhesive liner we all know that vendors from China have no problem making bogus stuff.

 
I rarely shop ebay - is the picture shown guaranteed to match the actual item? The reason I ask is someone else posted a picture of something they bought and it WAS NOT the same quality at all. Notice in the picture from ebay that the parts are all nicely lined up? On the item this other poster purchased the parts were all over the place, alignment wise, indicating poor quality control.
 

But for $9 you might as well try it.

 
You can get a 20" length from the place I linked to for $15 so you could compare.
 
 
Now in my application I was re-modeling a kitchen and spending $125 for the lighting strip was a drop in the bucket compared to the overall cost of the project. I've seen high end name brand under cabinet lights of a more traditional form factor go for $150 for a 24" unit. The stuff I used works out to about $27, if memory serves, for the same size.
 
Since I have had nothing but good luck with the vendor I referenced I have stuck with them and not price shopped.
 
 
If you do get some of each let us know what you find.

The lack of specs does make me hesitate. I don't see UL as an issue since it is low voltage. But the power supply should be UL. And the point about lousy quality knockoffs from Asia is well taken.

I already have line voltage stub outs under the cabinets for the existing florescent lights so I won't have to open the walls. Thin boxes are available that can convert stub out to an outlet like this:
http://www.amazon.com/gp/product/B004OLU9WK/
Although now that I look carefully I see they are 1.8" thick. I was thinking a thin wall wart could be plugged in but would also need to make sure the plug had the right blade orientation. Not as thin as I has hoped for. Perhaps I could run the stub into the bottom of the cabinet and put the box there. Or extend the wire and put it on top.

I also have some closets with the lights above the door on the wall I would like to replace. That would require a different solution to look good although it is hard to see.

 

[fcwilt]

I already have line voltage stub outs under the cabinets for the existing florescent lights so I won't have to open the walls.
.

 
Where do the stub outs originate? My electrician always runs the wires from each cabinet back to a central location in a multi-gang box of a suitable size. With this arrangement he can make the wiring serve high or low voltage applications.

 

[JimS]

The wires go to a switch on the wall in the backspash below the cabinets.  But its just a single gang box.  If you use your arrangement for LV where does the conversion from HV to LV take place?

 

[fcwilt]

The wires go to a switch on the wall in the backspash below the cabinets.  But its just a single gang box.  If you use your arrangement for LV where does the conversion from HV to LV take place?

 
The box is situated in a nearby closet or other such area where the visual aspect of such an arrangement is not an issue.
 
Then you only need mount a suitable power supply to the wall next to the box and do the needed wiring changes. 

 

[JimS]

I don't have that option but could put the supply in the cabinet if it doesn't fit under.  Here is a page on doing exactly what I want to do - same type stub out, etc.
http://mfischer.com/wordpress/2013/01/27/under-cabinet-led-lighting-install/
 
You can find anything on the web if you look long enough... 
 
He states he added a box for the 115V connection but no details.  I would need to find one. 
 
Here's a thin power supply - no idea about quality, was just looking for thin
http://www.amazon.com/Ledwholesalers-Suppply-Driver-Transformer-Output/dp/B0034GUEY4/

 

[fcwilt]

I have good luck with the Mean Well USA brand but that does not mean there aren't many others out there of good quality.
 
Power supplies for LED lighting are often called "drivers" and they may have features tailored to the application.
 
http://www.alliedelec.com/search/results.aspx?term=led+driver&navigation=4294887187-4294909560-4294911236-4294926993
 
You can find drivers that have adjustable outputs using built-in pots, external pots, 0-10 VDC inputs, etc.
 
In fact Insteon has this:
 
http://www.insteon.com/0-10v-ballast-dimmer
 
which I was intending to use with some LED drivers that took a 0-10 volt input for dimming.
 
It worked just fine but then I found that my home automation system (Elan g!), during a recent update, had stopped supporting Insteon and I could not get the Elan controller to recognize the Insteon interface.

 

[Neurorad]

Task Sempria UC LED lights include an integrated raceway
 

 
As an aside, here is what we went with for outlets over counter, under cabinet, Task Lighting angled outlets, TR series
 

 
Outlets available as Decora or tamper resistant.
 
We would have done it in the island, too, but the kitchen designer forgot about it when measuring the granite.
 

 

[pete_c]

Here I utilize MeanWell DIN mounted 12 VDC power supplies with two 12VDC outs on each device for LED power supplies.  The size / multiples of these devices have them mounted in the basement din rail adjacent to the fuse panel.  The prices of these devices vary (have 8) and historically were some $80-120 each depending on where I purchased them.  They are all 75 watt / 160 watt which is much higher wattage than the 30 watt ones I see (which are much smaller).  I did over do it on the power supplies and really didn't need to go up this high (30 watts should suffice for a few under the counter LED lamps.
 
Prices here (domestically) for MeanWell transformers are typically way higher than direct purchases from source.  That said you have to know where to find them which can be a real PITA.  Note that I do not work for the company MeanWell.  I just settled on using these based on what I read about their use in commercial applications.
 
Personally I would look for that ultimate well constructed thin power supply. (opinion)
 
MeanWell switching power supplies.
 
I have taken advantage of the use of conduit running between the HV multiple outlets providing granularity to the circuits / switches connected.  Here mostly I saw only 2-3 14 guage electrical wires running in the conduit which allowed for more wires / circuits.  Easy to fish wires with the distance to the boxes is short.  (I have not been able to do this with another home wired with Romex / plastic boxes as easily).  All the HV outlets over the kitchen counters here are metal 4X4 boxes with single outlet mudplate covers.  I have removed the single covers on a couple of them and installed automated switches (UPB).  (IE: this would or could provide me with additional automated LED switches per section of counter space).
I did add one automated switch which is paired with a secondary switch for the grill area of the deck as one window in the kitchen views that section of the deck.   It was a real PITA though because of the additional conduit run for said endeavor.
 
Doing a retrofit change of the current line voltage stuff (120VAC to LV) will provide you a good base for whatever you want to do in the future / LED lighting.

 

[bpal]

I did this last year in my remodel. I did under the counter and in a lighted soffit in the entry. Here are a few of my lessons learned.
 
If you plan to dim don't skimp on the power supply/drivers. I replaced all my power supplies after buying cheap originally. Even if you are not dimming, the cheap supplies that I bought initially would not turn off and on quickly. You'd be surprised how many times you forget something and need to turn the light back on immediately after you turn if off. I ultimately went with Mean Well and Magnitude. The Magnitude power supply (specs below) is built like a tank. The 40w MW is probably 4 oz. the 150w Magnitude is probably 6 lbs.  I dim with Lutron Radio RA 2 dimmers (RRD-6NA).
 
The aluminum extruded channel is very important for the LED strips. These things generate a lot of heat and you need some mass to pull that away. I went with the 45deg angle strips. The lowest profile might look nice but I would be worried about longevity with the high running temps.
 
I don't really see any quality difference in the ebay sourced vs other LED strips. I did sample both. I eventually went with ebay sourced and have been happy. Maybe I got lucky. I would recommend to buy all that you need and some extra at the same time from the same supplier. Variations in color temperature or brightness are fairly obvious especially when dimmed.
 
Here where I got my stuff. Shop around there are many suppliers.
 
LED Strips -
5630 LED strips warm – ebay
 
LED aluminum channel and diffusing cover -
www.1000bulbs.com
 
Power Supply / Drivers -
Mean Well
PCD-40-1750B
PCD-16-1050A
www.onlinecomponents.com
 
150 Watt – 12 Volt DC – Hardwire – Dimmable Magnetic Constant Voltage LED Driver by Magnitude (#M150L12DC-AR)
www.heracolights.com

 

[fcwilt]

The MW PS is light because it is a switching PS, thus no heavy transformer. 
 
The dimmable magnetic units are simple linear devices using a traditional iron core transformer (that and the case make it heavy) with common AC-to-DC conversion components. 
 
Both are fine technologies depending on your application.
 
If you only want to adjust the brightness and basically leave it alone after that you can put PWM (pulse width modulation) dimmers on the DC outputs of the PS.

 

[Swancoat]

I just replaced my under cabinet lights. I had fluorescent fixtures, all hardwired, and wanted to go with something softer and dimmable.

Eventually settled on some 'American Lighting' LED bars (Home depot was selling as 'Irradiant'). They were available in 8, 18, 24, and 32" sizes (maybe a 12" too... Didn't need that size though). They aren't on Lutron's approved list, but said they were dimmable with any incandescent dimmer and specifically named a few Lutron (nonRA) model numbers.

I went with 2 8" fixtures for my test. They installed relatively easily, and dimmed well with a CL dimmer. So I ordered 9 more for the rest of the kitchen (1 circuit has 1 fixture and another with 8).

I replaced the 8 fixtures and turned them on, and they looked great and were brighter than the old fluorescents.

Then I installed a RadioRA dimmer... And they buzzed. Very audibly. Wife got a frowny face. Ugh. So I got a phase adaptive dimmer, and that did not help.

After some troubleshooting, it was the 32" fixtures. I had one of them installed, and it seemed to account for 80% of the buzzing. Replaced it with a 24" and all is good. The circuit of 8 still buzzes, but is much quieter. Easily drowned out by the fridge. You have to go up close and 'listen' to hear it.

I'm now happy with these, but would stay away from the 32" (I suspect you could use two smaller ones with minimal audible buzzing).

 

[Desert_AIP]

This is the system I use.
The transformers are very well built.

http://www.environmentallights.com/led-under-cabinet-lighting/environmentallights-high-brightness-premium-led-under-cabinet-lighting.html

 

[JimS]

One thing I don't understand is the heatsinking provided by the channel. I have seen it mentioned multiple places and in general it seems reasonable but I don't see a good path for heat to get from the LEDs to the channel. I work with devices that need heatsinking - they get thermal grease or thermally conductive pads. If I put an LED strip in a channel does the path through the adhesive backing really provide a decent path for the heat? When I get some I may get out the thermal camera and see how much difference it really makes. I know that some high power LEDs have heat sinking provisions but that doesn't appear to be the case with LED strips. Or am I missing something?

 

[pete_c]

Playing a few years ago with those 1 watt Cree led lamps with a heat sink I would always burn my fingers on the heat sinks.  That said googled your question relating to strip LED lamps (old technology) and found an old post from 2010.
 
The LG Innotek 3 LED lamps shown above are embedded in some sort of heatsink material (almost porcelain like) with a clear substrate for the LED lamps. (.72 Watts per 3-LED module).

I'm very new to this, and have no idea how bright these are, or how much heat they will produce.

As i said in the past, i have used 5mm leds. The blue ones were 3.2v - 3.8v maximum, and the power supply was from a PC. I just
soldered 4 leds in a series and connected them to the 12v rail on the power supply.. Will i be able to do the same with these?
BTW, power supply is not in a PC, and is a 400w supply with 16a available on 12v rail.
 
In short, yes you will need a hear sink on these. You can just a strip of aluminum, as long as they are mounted to something using thermally conductive glue.
 
Each LED is rated for 300-400 mA, at 3.6-4v DC. Heat equals Watts in - Watts out. With LEDs, some of the power (watts) becomes light, but if you ignore that then you have a decent safety margin.

Power = Watts = V*I
We've got 2 voltages and 2 amperages. LEDs tend to need more voltage at higher amps, but we'll do 'em all.

3.6v * 300 mA = 1.08W
3.6v * 400 mA = 1.44W
4v * 300 mA = 1.2W
4v * 400 mA = 1.6W

So I'd expect about 1-1.5W of heat if you're running these things at 300-400 mA.

Voltage: If you have 12.0 VDC between those rails, you'll be running these LEDs at 3.0v each - they're likely to be dim. If you tried 3 LEDs, you'd be running them at 4.0v, which for the LEDs is likely to be screaming hot.

Consider adding a resistor. The way to calculate the value you want is: Pick a drive current (350 mA, say). Make the voltages add up. For 3 LEDs:

V(supply) - V(resistor) - 3* V(LED) = 0
12V - I * R - 3* V(LED) = 0

The voltage of the LED depends on current - I'd guess it's about 3.7v, but that's a WAG.

12V - .35A * R - 3*3.7 = 0
12V - 11.1 = .35*R
.9V = .35R
2.57 ohms = R. Make sure it's rated for at the very minimum 350 mA.
 
thanks for the responses, and the breakdown!

I just read "each watt of LED power needs about 9 square inches of surface area open to free air for cooling."

As for using aluminum strip, a 3" square piece will work? How thick should it be?
 
That seems to be extremely conservative. The average surefire 6p has around 17 square inches of aluminum exposed to air, LED's are regularly driven at 5 watts and this is just a single XR-E or XPG, and 10-15 watts seems to be the upper limit. This is also with a relatively poor thermal path compared to an LED directly mounted to a heatsink. The surefire 6p example can be rounded down to an easy 3 square inches per watt, which should be well within the margin of safety, but the heatsinks will get fairly hot to the touch. I suggest using 1/8 inch aluminum, or whatever thickness of U channel you can find close to that. 1/4 is better of course, but 1/8 is easier to cut with tin snips or a hacksaw to make fins. If you have any old computer heatsinks laying around these will work great too.