I want to install hardwired, under-cabinet lighting, but I need some guidance on what kind of devices (transformers/drivers/adapters) I need to complete the project. I know very little about electricity and even reading some of the electrical answers on this site (like this one) have my head spinning so I'm hoping somebody can just tell me what I need. Here is my situation:

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The rectangles (A-F) are my wall kitchen cabinets. The yellow wires (1-5) are the wires already setup (connected to a wall switch), on a single circuit, carrying 120VAC. 1 connects to 2, which is connected to 3 and so on.

I want to use something like this. LED Lights

However, my difficulty is most of these LED under cabinet light solutions on Amazon seem to be assuming that you have one set of cabinets, where you can link all of your lights in a perfect row, and one plug that you will then plug everything into. I don't have that. I have 5 120VAC lines, and one of those lines (#5) needs to have 2 lights interconnected (for cabinets E and F) on that one line (why it was setup like this is another story).

So if I were to buy the light kit above (or something similar), please tell me what [else] I need such that;

  1. I can plug a single LED strip (or puck) into the 120VAC lines on cabinets A, B, C and D
  2. I can plug two LED strips (or pucks) into the 120VAC line on cabinet E

In case it matters, the scenario illustrated here is slightly more simplified then my actual setup. In my actual setup, there are two more cabinets. One touching cabinet 'F' (call it cabinet 'G'), and another cabinet which is stand-alone just like cabinet A (call it cabinet 'H'). So there are really 8 cabinets, and 6 lines coming out of the wall, but I didn't include them in the picture to try to simplify the scenario. I add them here incase it matters (for voltage/wattage/amperage/gigawatt consideration).

Also note, I'll probably have somebody else do the installation, but I still want to know what I need so I have it ready for whomever does the install.

EDIT: It has come to my attention that I can run 12V DC current on Romex. So is there anything wrong with setting up a transformer at line #1, to convert the current to 12V DC continuing down the line to points #2-5? That way all I need is one transformer at cabinet A. Assuming the transformer can handle the load of all the LEDs total wattage, is there anything wrong with this approach?

  • I assumed that they all went back to a 120v source somewhere. If the wires are laid out in a way that you can supply 12vdc to the wires and they don't share a box with any 120vac wires, I think that would be a workable solution. I'm not sure if it meets the letter of the NEC (using romex and switch boxes for 12v), but I'm pretty sure the main issue is keeping low voltage and high voltage in separate boxes. – JPhi1618 Dec 10 '15 at 21:59

I just installed these under some cabinets, and they work great.

Most LED under cabinet lights are similar so... Each "strip" is made to chain to the previous strip. In my installation, the first strip is plugged into an outlet with the large transformer you have pictured, and then a 12v jumper goes from the first to the second, second to the third, etc. I have 6 lights in a chain.

You installed 5x 120v drops... You could have a transformer at location #1, #2, and #5, and chain #2>#3>#4 and #5>#6. For each separate 120v connection you will need a duplex outlet and a 12v transformer. For the lights that I linked, the barrel connector on the transformer needs an adapter to fit the smaller barrel of the lights, so pay attention to that as well.

Amazon sells the transformers and jumper wires separately, so you can buy them as needed.

Also note that your linked question is dealing with RGB "strip lights" that are cut-to-fit, so it's much more complicated than plain'ol white, modular LED lights.

  • When I search for 120V to 12V transformer, I get a bunch of different transformers, for different amps and watts. How do I know the kind of transformers I need? Is it the same for each cabinet/set-of-cabinets? What do you mean when you say I need a 'duplex outlet' for each connection? The 120V wires are already connected (on a single dedicated circuit I believe). Do I need to change the circuit (whats behind the walls)? What are jumper wires for? Do I need to use barrel connectors, on the transformer end, or can I splice wires and connect the LED to the transformer with a wire nut? – n00b Nov 11 '15 at 22:26
  • I'm not aware of any affordable, hard-wired 12v DC transformers that would be appropriate for this, so I'm saying you'll need to install a standard electrical outlet in each location and use a plug-in transformer (like you pictured). For the "right" power supply, try adding the name of the manufacturer or "LED" to the search terms - I found this. Jumpers are used to connect one 12v strip to another (like this ) – JPhi1618 Nov 11 '15 at 22:34
  • Thats unfortunate. I want to use the hardwires, and want to avoid having to 'plug-in' any plugs. +1 anyways – n00b Nov 11 '15 at 22:40
  • Here is an example of a hard-wired transformer. Not sure if it would work for you. It's high priced and high wattage, so not really made for your exact situation. Just trying to put a picture with an idea. – JPhi1618 Nov 11 '15 at 22:40
  • Since you do have 120v, maybe an older-style puck/halogen light would be better. Or maybe even small florescent fixtures. Unless you can find a direct-wire LED solution, I think it will be messier than you want. – JPhi1618 Nov 11 '15 at 22:42

"Gx53 LED Light Bulb 110 Volts 5 Watts Warm White with Lamp Base for Ceiling Downlight Under Counter Lighting (5 Watts)" These are available through Amazon and can be hard wired directly into your existing wiring with individual switches if necessary. Voltage transformers are only another unnecessary weak link you can do without.

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