I recently renovated a kitchen which included installing new cabinets. The owner wanted to have task lighting mounted directly under the cabinets over the main food prep area. She did not want the halogen puck lights because they are hot and the bulbs burn out too quickly. I suggested LED lighting and, with her agreement, set out to find some acceptable solutions.
To make a long story short, the LED lighting on the market for under cabinet installation is pricey and there is limited selection of styles. So I set out to design a solution and came up with this great alternative using readily available LED Strip Lights.
Parts You Need
I had to buy some 3/8″ aluminum C channel and a roll of LED Strip Lights plus power supplies. I found the first strip light solution on the Home Depot website, but at 128 Lumens per foot, the 4 foot space would get me approximately 500 Lumens of light – less than a 60W incandescent bulb. I figured that I could double it up, but it might not look as elegant. It was $70 on the internet store, plus I had to buy the power supply at $40. I set out to go to the local HD store and found little or no stock, and where I did find it, the actual store pricing was dramatically different. The solution was going to cost about $150 in parts if I bought it in the store. Also, the specs were not what I wanted.
I went on the internet to find other suppliers and came upon one that sold many varieties of strip lights. I wanted a “Warm White” color and high brightness and found this one rated at 300 Lumens per foot. Since I knew I would need only about 4 feet, I decided to buy two power supplies so that I had a spare power supply for a different project using the remaining length of LED Strip Light. Total cost: $70!
Step 1: Calculate the Electrical and Lighting Requirements.
This particular strip light was rated at 4.4 Watts per foot. Since I was using less than 4 feet of the strip light, I expected to need 17 Watts for the total project. The 24 Watt power supply has plenty of reserve power and it wasn’t going to operate at max power when the lights were on. I always build in a margin of at least 25% when powering electrical loads. This power supply is nearly 30% more power than needed – perfect!
The next step was to ensure that the LED’s would not get hot. I decided to use aluminum C channel to mount on the cabinet and stick the strip light to that. In this way, I could remove the light assembly from the cabinet if necessary, plus the aluminum makes a great heat sink to dissipate any residual heat from the LEDs. I drilled some additional holes into the sides of the C channel to add more surface area and allow air movement which increases the dissipation of emitted heat.
Next, I calculated the lengths and lighting requirements for each cabinet. I needed 16″, 20″ and 10″ strips. The LED strip can be cut in 2″ intervals anywhere along the length of the 16 foot strip that I purchased making this easy. Just cut it with scissors on the lines as marked on the strip. The total length was 46″ or 3.8 feet. At 300 lumens per foot, this meant 1150 Lumens of task lighting which is a little less than a 75W bulb. Nice and bright!
I cut the three strips and soldered lengths of 14 gauge stranded copper wire (at these lengths and power levels, 18 gauge would work fine too.) On each strip, I soldered the red wire to the “+12V” terminal (anode) and the black wire across the R, G, and B terminals (cathodes). Note that the “RGB” designation means they use the exact same strip for color LEDs too and the white LEDs will need to have all their cathodes connected.
Once they were mounted under the cabinet, I twisted all the red wires together and connected them to the +12V wire from the plug-in power supply, and the all the black wires to the “-” or negative side of the power supply.
One last [green] thing. I did not want the power supply energized all the time using an in-line switch in the 12V wires to switch on the strip lights. This wastes electricity because the power supply is always on. So I installed a light switch in the back splash and connected it to an electrical receptacle that fit behind the corner cabinet out of view. [You may need an electrician to do this part.] In this way, the light switch would turn on power to the power supply only when needed. This design saves electricity because no electricity is flowing through the power supply when the light switch is off.
I decided to video record the entire process of howto assemble and install under cabinet LED lighting for those do-it-yourself project enthusiasts here:
Parts and Tools you may need:
Scissors, screwdriver or drill/driver, utility knife, soldering iron, solder, wire strippers, measuring tape, hacksaw for the C channel.
LED Strip Lights, power supply (big enough to power your strip length – about 4.4W per foot), 3/8″ aluminum C channel, wire, wire nuts (or electrical tape), mounting screws.
Skill Level: Medium
I hope you find this article on how to make your own under cabinet LED lighting useful. Let me know of questions in the comments section below. Enjoy!