Previously when you prepared food in my mom's kitchen you would be standing between the ceiling light and your work surface, thus casting a shadow. Additionally, under cabinet lighting tends to look nice. It's quite the dramatic effect in person and definitely stepped up the look of the kitchen a lot. It's less harsh of a light in person and significantly improved visibility while working in the kitchen.
Cost & Power Usage
I was able to light my mom's entire kitchen for under $40.00 including all parts. Additionally, the lights are quite power efficient, using about 3 watts per light tube (I used 6 pair / 12 tubes total). Total wattage=36 watts, or 3amps at 12V. This is a little over half the power usage of a normal 60watt incandescent bulb. Your final project price will vary depending on your supplies and the size of your kitchen.
Compare With and Without
1. Under cabinet lighting on, Ceiling light off.
2. Under cabinet lighting off, Ceiling light on.
3. Both under cabinet lighting on and ceiling light on.
Step 1: Collect the Parts
Details for a few of the parts are listed further below.
1. Cold Cathode Lights w/ Inverters* (2 light tubes per inverter)
2. Power Supply (12V DC for these lights)*
3. Wire for connecting power to inverters
4. Staples or something else to hold up wires under cabinet
5. Power Switch (optional)
6. Inline Fuse (optional)
7. White Paint* (optional; see below)
1. Wire Cutters
2. Soldering Iron
4. Electrical Tape
*Cold Cathode Tube Kits
I used white 12" tube kits from petrastechshop.com. They put out quite a bit of light and come on quickly. The light is less harsh in person than the camera makes it appear. They were on sale at the time for $3.75 or something. Shop around for the best price. Make sure the kits you get come with TWO 12" tubes and an inverter. Some places try to trick you with just one tube included for the same price. One of my tubes didn't light and I emailed the store and they sent me a working replacement which I received two days later.
I used a HIPRO brand DC Switching Power Supply designed for a laptop. I got it from sciplus.com for about ten bucks. It's rated for 3.33A at 12V, aka 40W (watts = amps * volts). It gets quite warm as I'm approaching it's upper rating. Each individual lamp uses about 3 watts (6W for a pair) so total up your expected usage and get a supply over that. I am using 12 lamps (6 inverters) for a total of about 36 watts.
Before you start wiring things up, decide if you want to paint. If so, paint first so it can be drying while you work! Depending on how bright you want the lights to be and the color underneath your cabinets, you may want to paint under your cabinets to help reflect more light. I opted to paint the bare wood under the cabinets white to help with reflectivity so more light would reflect downward. This is entirely optional but it should help. Other colors may help soften the light, such as a pastel tan or yellow.
Step 2: Prepare for Wiring
See Step 1 for information selecting parts.
1. Power Supply
Point A in Figure:
With the 12V DC power supply unplugged, prepare it by cutting off the small DC connector on the output. If you're extra handy with things and have a jack/plug that fits the 12V connector, you could solder in a connector like I did so you could replace the power supply easily. I found the connector on an old set of computer speakers. Separate the two wires of the output and use a multi meter to check which wire is positive and which is ground. Mark this wire for later and unplug the power supply.
NOTE: If installing this in a camper or place where 12V DC is already available, you can skip the power supply. DEFINITELY use an inline fuse in this situation though to protect your power source and wiring.
2. Fuse (optional but recommended)
If you are installing an inline fuse, connect it inline on the positive DC wire, near the power supply. It is best to put this close to the power supply before the switch for the most safety. This is useful if you get a short so wires don't melt or catch on fire. Most power supplies include a fuse in them but an extra one won't hurt and it may also save your power supply from damage. Choose a fuse slightly higher than the maximum current you expect your setup to use.
3. Switch (optional but recommended)
A switch is useful if you want to be able to easily turn the under-cabinet lighting on and off. I used a lamp switch a friend had. Make sure it is rated appropriately. If your power outlet is on a switch you can just use that instead. You can also just plug and unplug the power supply but you probably don't want to do that all the time as things may wear out and it would be inconvenient.
Point B in Figure:
Cut off any cabling, switches, and plugs going to your inverter's INPUT, noting which cable is black or connected to the black wire. This is your ground. Do NOT cut off the cables going from the inverter to the lamps.
Step 3: Connecting It All Together
1. You will want your inverters to be wired in parallel. I soldered all of my connections for added durability and to lessen resistance. Your connections don't have to be beautiful. This is a simple job of connecting wires.
2. Unless your lights are going to be very close together, you will want to use additional lengths of wire to connect to your power supply to each inverter. I ran a single line of 2-conductor appliance wire around the kitchen and cut into it periodically to splice into.
3. Connect the wire coming from your power supply's ground to the ground on all of the inverters. Connect the positive wire to the switched positive wire. See the diagram below for more information.
4. Be sure to properly insulate all ground and positive wires from touching and secure all connections so they are tight. You can use the multimeter to check your wiring at this point and then give it a test.
5. If things do not immediately light, turn it off quickly and unplug everything. Begin to troubleshoot. Visually inspect connections, use your multimeter to find problems, and input extra stuff to narrow down the problem.
6. If all is well, move on to mounting the lights in the next step.
Step 4: Mounting the Lights
Be sure to note how the lights will be visible at different angles. Keep in mind things like different elevations of rooms nearby. For instance, my mom's kitchen is higher than the next room so while in the next room you are low and you can see the tubes. Also keep in mind where you will be placing the inverters and routing wires.
The kits usually come with velcro backed with adhesive. Depending on the surface underneath your cabinets this may work fine or fail miserably. Underneath my mom's cabinets the wood is very rough so the adhesive can't get a very good hold. On smooth surfaces the Velcro adhesive sticks exceedingly well. Peel off the protective paper on one side of the Velcro and stick it to the ends of the light. Remove the protective paper from the other side of the Velcro and stick it under the cabinet, spacing as desired.
Other Mounting Ideas
Epoxy: Simply epoxy it up using epoxy rated for adhering to plastic and wood.
Cable Ties & Staples: Staple a cable tie loop around each end of the light and inverters.
Metal "U" brackets: Nail or screw in metal "U" brackets from the hardware store to hold everything.
Drill holes and cable tie: Drill small holes on each side of the light and loop a cable tie through.
My mom's friend ended up enhancing our mounting later since the velcro began to fail since it was applied to very rough wood and couldn't grip it well.
Step 5: Finishing Touches
Use staples or other cheap wire management hardware to hold up your wire. You can find all sorts of hooks things for holding up wires at your hardware store or even the ever-present Wal-Mart. I used raised staples with a staple gun and it was fast and easy. Just take care not to puncture any cables. Don't use a staple gun that doesn't leave the staples sticking far out of the surface or you should cut into the wire.
Hiding the Lights
If your lights are visible, there are a few ways to hide them and make them more pleasing. You can add some trim to the edge of your cabinets to obscure the view, or you can go to your hardware store and find plastic hoods to fit over them. Though my mom's are slightly visible from the other room since the kitchen is raised, we opted to leave it as is since it looks great when you're in the kitchen.
Keep the Power Supply Cool
Be sure to get a power supply that is rated high enough for your setup. Mine is being pushed pretty hard so it gets quite warm. It is within limits but to help make it last longer I cable tied on a couple of CPU heatsinks with CPU grease to help dissipate heat. It seems to pull the heat off pretty well. Be sure to keep your supply in ventilated area and not to put stuff on it. If I did this over, I would get a slightly higher rated supply so it wouldn't be pushing it to so close to its max current output.
I hope you found this instructable informative and useful. I was able to significantly improve the lighting in my mom's kitchen on a tiny budget. While pricing 'professional' under cabinet lighting systems, the prices for this kitchen ranged from $400 to $2,000. I think my $40 version was well worth it, especially compared to the professional version's much higher costs.