Somebody initially wired up six 12 vac 10 w halogen bulbs under my kitchen cabinet, wiring them in parallel. The 12 vac power supply was putting off a lot of heat, and within a day or two appeared to burn out. Prior to that I questioned that the power supply was enough to power the 6 bulbs and, trying to recall some basic calculations from physics class 25+ years ago, I think the math showed that we were pushing the transformer beyond the load that it was created for.
So with with the wiring in place, I'm thinking about replacing them with some form of LEDs instead. I think that the power requirements for LED's will be significantly lower and I do have a large box full of assorted transformers that might work as a power supply.
Rather than purchase a kit from a store, I'm thinking of using the existing wiring that's running through the cabinets, purchasing high output LED's and whatever components I might need (resistors?), warming up my ancient soldering gun to wrap this job up.
How would I go about this? What types of LED's should I use, and how would I go about figuring out the power requirements for this set of 6 lights? Should they run in parallel or in series?
Best Answer
You can buy LED fixtures off the shelf, which are basically ready to go. I've seen these as puck-shaped lights that are basically designed for under-cabinet or shelf lights.
There are other pretty simple off-the-shelf solutions as well, such as using rope light.
If you are talking about using raw LEDs and literally doing everything yourself, it's pretty simple. You need to get some high output LEDs (pay attention to color temperature, beam angle, etc to make sure it is suitable). You can get LEDs in different packaging: clear/diffused, large/small, forward/side-emitting. Likely your best bet will be a large frosted one. How many you need will just depend on how much area you're covering, and how bright you want it.
You'll need a DC power supply. The exact values are all dependent on what you use, so it's very hard to give an answer here. There are online LED array calculators available, which can give you something like this:
One of the major disadvantages of serial wiring (shown here) is that if one LED is disconnected or burns out, they all go out. Finding which one is broken can be difficult, and if you've ever done this with x-mas lights you'll understand what I mean.
Another possible disadvantage of the DIY solution is that you are either going to have to come up with a nice way to package this all underneath, or you'll have a bunch of wires and bare LEDs hanging under your cabinets (maybe hidden by some moulding, but still). This may turn off future potential buyers. Off the top of my head, using some split-loom tubing may be a way to hide the wires and make it look at least half-decent.