I've been looking into this a bit more. I used to think that, under the hood, all xenon UC lights were low-voltage, and that it was just a question of whether the transformer was internal or external; for a long time I couldn't find anything to contradict that idea. I've since found some xenon UC lights, such as one line offered by Pegasus, that are truly line-voltage. So, it turns out I was wrong. Sorry for any confusion I might've caused. Some low-voltage fixtures are open-air arrangements, which I think would dissapate heat into the room more efficently and not seem as warm. Some low-voltage fixtures require remote transformers, the installation of which is a bit more complex than simply connecting a complete fixture to standard household current, so low-voltage installation may be a bit more time consuming and/or expensive. Line voltage fixtures are dimmable with cheap, common dimmers, whereas dimmers for LV lights are considerably more expensive. The most important thing to be concerned about might be the thickness of the fixture. I just scanned Kichler's offerings, and their line-voltage fixtures are an inch and a half thick while their low-voltage fixtures are only an inch thick. That could make a difference, depending on the height of your light rail.

fluorescent bulbs under cabinets will be T4 or T5 ; these are long and thin -- think of light sticks, not round / spot / pucks. I gave you search terms. I'm sure you will find out stuff. All bulbs generate Some_Heat; the wattage is a key indicator of heat. Xenons are in the same family as halogens and old-fashioned incandescents (the bulbs we had in the 20th century), which is not efficient technology in terms of producing light (as opposed to heat). Searching, I read that xenons are only 10% cooler compared to regular halogens. That is still Hot. So incandescents, all types including xenon-halogen, make more heat than the other means of producing light (fluorescents and LED's). Fluorescents give more lumen (light) and less heat than the incandescent family (xenons, halogens). Fluorescents come in the range of 6 watts to 25 watts; that is fewer watts than the incandescent family needs. Incandescents use more watts to match the lumen, and the extra electricity goes into heat production. They are a heater and a light. LED's come in the range of a fraction of a watt. LED's are lowest wattage but they are so weak they don't produce much lumen (light). So they are good for accent lighting. If you buy large numbers you will get more light. you would have to install hundreds of them, to match the 1000+ lumen output of fluo or incandescent. Has anyone out there installed a hundred LED's under a cabinet? HTH -david

Annab6. Mine are open fixtures. Each lamp is rated at 10 watts. The lamp holders attach to a flexible cable and can be spaced as close together or as far apart as you like. Mine are at 6" intervals. The light projected is very even across the countertop. It is not super brilliant, but more than sufficient to evenly illuminate the countertop that would otherwise be shadowed by the upper cabinets. The light is a very pleasant and natural incandescent white color. Excess heat is not something that I've ever had cause to think about. They simply don't give off much heat. The xenon lamps are also dimmable. I have the under-cabinet lights switched on more than any other lighting in the kitchen. As soon as the sun goes down, the under-cabinet lights go on. When I'm cooking, I also turn on the recessed halogen fixtures that are mounted in the ceiling over the countertops. When I'm done working, the ceiling fixtures usually get dimmed or turned off, but the under-cabinet lights remain on. They remain on until I'm turning out all of the lights in the house at bedtime. You can see an image of the lamps and fixtures that I have in the link below. Here is a link that might be useful: Sea Gull Linear xenon lamp & fixture

Yes; they are the fixtures; what they list on their undercabinet LED page as light arrays. We have two runs; we were able to do the wiring as part of the remodel while we were down to the sheetrock. If you look at the specs for the lighting, you will see that there is a 6' power supply cord. One end plugs into one end of the light array. That cable then goes into the wall and comes out behind a base cabinet. The lights are wired to a switch; wiring from the switch comes out at the same point as the power supply cord. The two are brought through a hole in the back of a base cabinet. The wire to the switch is spliced to the power cord of the transformer (after cutting off the plug). The power supply cord plugs into the transformer. The transformer sits in the cabinet. For one run, we have the transformer at the bottom of the cabinet behind and under a drawer; the other happened to line up with the cabinet that holds our trash pullout. That had a little shelf between the bins and the top drawer; the transformer sits on the shelf. Here is a little drawing; hopefully it will make this clearer: