Use low voltage lights if they are incandescent.

120 V bulb filaments are not very rugged, and normal vibration from items going in and out on the bottom of the cabinet will greatly shorten their life, and the bulbs are not inexpensive.

For puck stye incandescent lights small 60 W power supplies are easy to install (they go on the bottom of the cabinet like the lights)and each one can handle three 20 W lights.

It helps greatly. We did not have ucl before, but now we use the ucl more often than the main lighting now.

If you're considering led ucl, direct wire eW PowerCore Profile might be more cost effective solution. It is dimmable and low profile.

Direct current ucl led could either be 12v or 24v. The dimming power supply could be a significant cost .

UCL is almost a MUST if you have dark counter top. If you have granite (or the like with mica embedded) the light bounces from granite and adds beauty to the countertop.
It's very helpful as you age and your vision is dimming, as task light. it's very nice to have as low light while dining / entertaining and not requiring full lights in the kitchen.
They are usually cheap to operate, especially on a dimmer and give a very upscale sophisticated look. I use them all the time, sometimes early am in winter when I don't want much light, just TASK lighting.

Thanks all for the feedback!

We're now considering to use LED UCL:) So, the question now is: should we get them on a dimmer or not? Both the dimmable transformer and the dimmer switch seem costly($60 for the transformer from Inspired LED, and the dimmer about $40).

Thanks again!

We've had them in several kitchens without dimmers and with no regrets.

Do the cost analysis for both direct wire and various dc vendors.

The following link could be helpful.

Here is a link that might be useful: LED UCL DIY

Cons
Flexible strips tend to have lower light output since the conductors cannot dissipate as much heat and carry less current.

The strips need to be handled with some amount of care to avoid breaking smd (surface mount device) solder joints.

The bending direction is most likely orthogonal to the direction you would like the strip to bend.

Pros
They are more easily cut, which probably works better for some.

The profile is significantly lower. Can be used at the toe kick.

They also cost less (in general).

I would strongly recommend pricing several alternatives
1. Do a mock layout of strips (sized to fit). The strips may come in 6", 12", ... sections, depending on who you get them from. You need to confirm with your cabinet maker whether the cabinets have a flat bottom all the way (cabinets 15, 14). Cabinet 12 could be on a separate run.
2. Count all the strips and interconnects under the cabinet.
3. Plan the location of your transformer (assuming low voltage). It needs to be accessible.
4. Estimate the length of wiring needed.
5. Figure out the gauge of the wire given the total length, power consumption of each run. EnvironmentalLights has a nice table to help. The calculations are available on other sites too.
6. Add 10 - 15% margin to get the size of the dimming power supply.
7. Depending on the power supply, you will either use an electronic low voltage (ELV) or magnetic low voltage (MLV) dimmer. Never use an incandescent dimmer.

For the eW PowerCore profile from Philips, you just need to figure out the lengths needed, number of interconects and the place where the (AC 120v) wire will come out from the wall. It uses a ELV dimmer.

If you intend to light the toe kick, plan on having a separate circuit. Most likely, you'll need to use flexible light strips for that area.

Thanks davidtay again for the info!

I've got a couple quotes now. You are right that LED strips can be cut to fit each cabinet width, and they're cheaper than the light bars.

One of the vendors also included some custom inwall cable in the quote for inwall wiring. It's a little pricy(about $40). Is it necessary? Is there standard wire available?

Thanks again!

There are various gauges (thickness) of wire available. Depending on the length of the wire used and the power draw of the run of led lights, you may need thicker/ thinner wire. For example, if the power draw of the lights used is ~6 watts (24 V, 0.25A) and the length of wire involved is With low voltage lighting, the wire gauge is crucial.

Custom wire usually costs more and may not be sufficiently long.

Thanks again, davidtay!

Would the low voltage speaker wire work for this purpose?

Most likely yes. Do the calculation first.

Here is a link that might be useful: wire gauge calc

"One of the vendors also included some custom inwall cable in the quote for inwall wiring."

Concealed wiring in the wall has to follow the NEC and be an approved wiring method.

I would be very curious if the "custom inwall cable"
has an appropriate listing (approval from a lab).

I found a few vendors online for this product, but haven't found any vendor ratings. Also one on ebay. Looking for the best price and reputable dealer. Any suggestions? Thanks!

Also...these lighting bars have built in transformers, correct?

Whatever type you use, just DO it! I have Juno Trak 12, where you can add bulbs if you wish. It's warm lighting, not cold white. I don't think I've replaced every bulb twice yet -- in ten years. These are on ALL the time after dusk. I have them in my glass-front cabinets too.

The only other kitchen lights I use daily are the exhaust hood lights and over-sink lighting. (Wish I could get rid of the cans that I never use.)

If you don't want to deal with a separate transformer, get hard wired lights. The eW profile powercore strips are good.