Led under cab. Idea ??

[EricU]

Maybe Robert is thinking of the skin effect in DC currents?  But I can't think of any reason not to use oversize wires

I'm confused about the current system.  Is it hardwired with romex to each light?

[Robert Adams]

I'm afraid all of that is incorrect.

Never said i knew why but in practice running dc on big wires long distance doesn't work. BTDT many times and it doesn't work. Too much loss.

[Robert Adams]

You cannot combine 12v and 120v circuits in the same box.

Avoid doing that, and feel free to run 12v over NM.

Similar discussion here:

http://forums.mikeholt.com/showthread.php?t=115729

Yup mentioned that earlier as well. Makes it really tough to do lighting now. Hence the plug in power supplies.

[vernonator]

I am in the same boat - existing 120v HARDWIRED fixtures are starting to fail and I would like to replace with LEDs. So you are saying I could wire in a power supply at the front of the circuit, and use the existing romex wire to run the lights? As said above rewiring is not an option, I have lights under the cabinets (separated by windows, sinks etc) and above the cabinets (separated by windows, sinks, etc).

[Phil Thien]

I am in the same boat - existing 120v HARDWIRED fixtures are starting to fail and I would like to replace with LEDs. So you are saying I could wire in a power supply at the front of the circuit, and use the existing romex wire to run the lights? As said above rewiring is not an option, I have lights under the cabinets (separated by windows, sinks etc) and above the cabinets (separated by windows, sinks, etc).

Yes, you can run 12VDC over anything that previously carried 120VAC.

Once again, don't run 12VDC and 120VAC in the same box.

[EricU]

I am having a failure of imagination as far as 120v under cabinet lighting goes.  Seems like the 120 comes into the j-box that the wiring to the lighting goes to, so at a minimum the wires being converted to 12 volts or the 120 volt wires would have to be removed from that box.  And probably a new jbox should be used.

[Cub_Cadet_GT]

Our under cabinet lights are switched from 1 switch.
Trying to figure out how to use existing wiring and switch to control 12 volt light tapes.
If I installed an extra box, next to the switch box, can I put a transformer in the box, and run the 120v power wire, into the switch box?
Then disconnect the original switched wires from the switch, and connect to the 12  volt output on the transformer.

I just went through this with my new house.

it has a somewhat cut up kitchen and to do all the under cabinet lighting without running new wires I needed 5 separate power sources, but like you I wanted to have one switch to turn them all on and off.

I ended up using these and absolutely love it.

https://www.amazon.com/Sylvania-Osram-Li...B01NAIVUBL

It ties all 5 separate systems wirelessly into one centralized controller. I hid the transformers inside the cabinets.

System was not cheap, but I did get mine during black friday pricing at Lowes a couple years ago for about 1/2 that price. I have a single battery powered switch that is mounted under one of the cabinets by the kitchen entryway and it wirelessly turns all the systems on or off. It has been flawless for about 2 years now and I cannot state how happy I am with it.

The kids also love that I can change the colors for fun events or holidays. Not that we do that much.

[Bob10]

I have to look some more but I am betting there is an led retrofit for the fluorescent tubes.  I really hope they have them as I have installed that type lighting in a few of the rentals kitchens too

[EricU]

not putting it past some enterprising person to make a replacement bulb, but it seems to me that it's more likely you'll have to replace the entire unit.

[brofessor]

I don't know how your kitchen is laid out so this may be unhelpful, but most under cabinet installs I see are fish a new wire above the cabinet from the switch. Put the driver above the cabinet then run your new 18/2 low voltage wire inside the cabinet in one of the front corners. You'll need to drill a small maybe 1/4 to 3/8 hole at the top and bottom. Use sticky backs and tie wraps or something similar so it's completely hidden on the backside of the face frame. It'll pop out at the front of the cabinet on the underside and terminate on the led strip.