Electrical Wiring for Under Cabinet Lights
arnoldk
| Posted in General Questions on
Hi,
I am currently doing the electrical rough-in for the house and my wife wants under mounted kitchen cabinet lights. Most that I am finding seem to be LED light design to be plugged into a receptacle.
Anyone recommendation for hardwire lighting to be operated by one switch in a L shape kitchen?
Thank you,
Arnold
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I've used LED strip lights for under-cabinet lighting in my last kitchen remodel, and a new build for my daughter - and will be using those in my new build as well. DiodeLED is one excellent brand among a few others; I'd avoid the oddball brands on Amazon.com. I think the LED strips provide a more even distribution of light than the "puck" lights.
In brief, you run low-voltage (16/2 or 18/2) wiring from the underside of the cabinet(s) to a location where you can mount a step-down transformer, which provides either 12 volts or 24 volts to power the lights; the line side of the transformer is fed from a switch, or better still, a "magnetic low voltage dimmer" (MLV).
The low-voltage wiring should exit the wall at a height slightly above the planned bottom edge of the cabinet; leave at least 18 inches of wire exposed for future connection. When cabinets are mounted to the wall drill a small access hole in the bottom rail of the cabinet back and route the wire through the hole.
Mount the LED strips about 2 inches from the bottom front edge of the cabinet and connect them to the lengths of low-voltage wiring routed through the cabinet mounting rail. You can purchase metal channels to which the LED strips are exposed (the backs of the strips have a peel-and-stick adhesive), and the channels are then attached to the bottom of the cabinets with short screws and U-shaped brackets.
You can either solder the low-voltage wiring leads directly to the LED strips or splice it to pre-made connector pig tails that slide onto the end of the LED strips.
It might be a bit more work than plugging a strip of puck lights into a wall outlet, but the end result is definitely worth the trouble.
GE makes their "Premium linkable" lights, which can be bought from the orange and blue stores, along with many other places. They are not the cheapest, but the quality is good and they make a hardware kit for them. Note that the hardware kit does require a small surface mount box to be installed though, so you'll need to plan your system before installation to be able to conceal things as much as possible.
Note that if you have the tools, you can purchase parts for the connectors they use for their linking cables so that you can make your own custom length cables instead. The parts are available from electronic component suppliers like Digikey. I don't recommend doing this if you aren't familiar with using a commercial crimp tool though, since it's more critical than the usual hardware store terminals.
Bill
You should take a look at IKEA's Tradfri line. Their system is modular so you can gang together (or mount and wire them completely separately) assuming your cabinets are 15", 18", 24", 30" or 36" wide. They are nicely designed, very low profile and the Tradri driver (what you plug the LED lights into) has a wireless zigbee chip integrated so can be added to most automation hubs, or just powered old school via a switched receptacle. You can also dim them via a simple wireless wall control (no automation hub needed). They are very hard to beat at the price point.
Pics of my last project using the system during contruction and at completion. I use automation extensively so everything is turned on and off by motion in the kitchen. Ikea also sells wireless motion sensors for their Tradfri lights, again at very reasonable prices.
If you want or need to strictly follow the code it become difficult.
You get into the different classes of wiring what voltage and what wattage and what version code are you trying to appease.
Most of the manufactures have decided to go with a wall wart power supply to make getting along with the regulators easy for them.
You could install a switched outlet for a wall wart in an unconscious location and run low voltage wires to the locations where you want light strips. Some would require the permanent wires be Romex seems like over kill to me.
There is stuff like this link if a $500 + solution is acceptable.
https://marvellighting.com/product/powerline-200-hard-wired-driverless-ac-led-tape-light-by-alloy-led/
Walta
Thanks for all of the information and links. I'll have to make a decision in the next couple of weeks if I mover forward with a low voltage or a 120v lighting system so it can be all wired up before drywall.
Thanks,
Arnold
Is there any reason to use anything other than a 18/2 wire?
Thanks,
Arnold
You aren't premitted to run zip cord type cable in the wall. Zip cord can be used under cabinets when properly supported (using the little clips made for the purpose), but you have to use the correct box to transition it to "building wire" (typically NM-B or similar) for the in-wall wiring. Some lighting systems have little boxes made for this purpose, others give you a cord assembly that plugs into a receptacle. The hardwire options usually give a neater finished appearance, but require more work to initially install (although in a new build there probably isn't much difference).
Bill
You can get low voltage which are design for in wall purpose similar to the HVAC and door bell.
I am just wondering if there's any reason to use anything larger than a 18 gauge wire for a typical kitchen LED lighting.
Thank you,
Arnold
Low voltage is different. I probably should have mentioned in my post #9 that I assumed you were asking about line voltage (120v) lights. Low voltage lights allow more flexibility, and just require a wire rated for the purpose, which typicall means CL2 or CL3 rated wire in the US.
Note that the cable types are a hierarchy, so you can use CL3 in place of CL2, but not the other way around if CL3 is required. Personally, I would use CL2R, CL3R, or CMR rated wire here, which is a little safer in terms of fire, since it has to pass what is called the "vertical flame test", which means it has to self extinguish after so many feet. The "R" stands for "Riser", and riser rated wire is likely to help flame to spread in a fire.
If you're thinking of wire guage alone, then that's determined by the load current. The issue you run into is that all this stuff is supposed to be "power limited" if you're allowed to use low voltage wire here, and you use table 402.5 for sizing the wire (6 amps for 18 gauge, 8 amps for 16 gauge, etc.). There are a few other rules, but you probably won't run into those unless you try to run loads of low volt lights on a single cable.
Bill
Thanks Bill.
I just need 18/2 CL2R wire running three home run back to the driver but I was wonder if anyone thought it was worth going with a large gauge or a 5 conductor for future proofing.
Arnold
5 conductor probably doesn't gain you anything in this case. Heavier gauge may make sense if the run is long or the load is high. If you can post the length of the run (and don't forget the "ups and overs" going up or down walls to get to ceilings or floors), and the load, I can check volt drop for you.
Bill
Around me, undercabinet lights seem to be universally wired with 14/2 romex. New construction is hard wired lighting, some hard wired kits do come with specific link cables between low voltage emitters which are pretty easy to run behind cabinets.
If you need to extend the link cables for a long run, there are junction boxes you can buy to connect to a 14/2 run inside the wall but usually simpler to install another driver in the remote location. Some drivers only have room for one 14/2 connection in which case run the 2nd 14/2 back to the switch.
The benefit of a 14/2 is that it is much more flexible, anything can be connected to it.
Be sure to read this article on kitchen lighting from David Warfel. He knows his stuff and is a big proponent of LED strip lighting for under cabinets. He gives product recommendations and other helpful information in this piece: A Detailed Illustration of Ideal Kitchen Lighting.
I don't have a subscription to Fine Homebuilding.
Arnold
You get one free article. This is a good one, but surely if you're building a house you'll save more money by buying subscriptions to GBA and FHB?
My parents gave me a subscription to FHB as a Christmas present for many years, it was a wonderful gift.
Hi AKOS,
I had read that using 14/2 with low voltage can cause issues though that may have been a thing of the past. I suspect the main reason is it's more difficult to hide a #14 compared to a #18 wire,
I will be pulling home run to the utility from three location near to bottom of the upper cabinet. My longest run is not going to be more than 10 feet so voltage drop is not a concern.
Thank you,
Arnold
That should work. Normally all the wiring/driver/junction box is at the cabinets but since you have pretty short runs, it doesn't matter much.
It sounds like you are determined to go with in wall low voltage wiring.
You need to understand what version of the code you are going to comply with the requirement are very different in the last few versions.
Learn about class 2 wiring.
https://www.elementalled.com/low-voltage-safety-understanding-class-2-compliance/
Class 2 is less than 24 volts and 100VA maybe more if you have the latest code approved. So, you could use12 volt and up to 2 amps.
Every part of the system must be labeled Class 2.
If you spend more than 15 minutes reading about class 2 wiring you likely to know more than the inspector on you job site about class 2.
If you have the correct electrical boxes the 120 volt and 12 volt connections will never be in the same compartment.
https://www.amazon.com/18AWG-Voltage-Conductor-Jacketed-Speaker/dp/B01N26MMWD?th=1
https://www.diodeled.com/lo-pro-junction-box.html
Walta
It's probably worth mentioning to avoid "CCA" (Copper Clad Aluminum) wire, which you find a lot on Amazon and Ebay lately. This wire is specifically disallowed for network installations (Ethernet, etc., such as "Cat5", "cat6" etc), since the standards body that defines those "category" specifications specifically states that the wire has to be solid copper.
Using CCA for low voltage applications is also questionable, due to longevity concerns with the wire itself. Make sure you're buying your wire from a reputable supplier to avoid problems.
Bill
Thanks Walta for the tip on the DiodeLED Lo-Pro junction box. Really like that design.
Now off to researching quality dimmable LED strips or dimmable Class2 transformers that can be used with home automation systems (or Lutron Caseta 120V dimmers).
Looks like the Magnitude Lighting JBZN-Series (with either E-Series or SOLIDRIVE PRO-V) is a good option for me, since I want to independently control various LV LED circuits and it allows TRIAD dimmers for different zones:
- kitchen under cabinet lighting
- kitchen toe kick lighting
- kitchen shelving lighting
- stair walkway lighting
- bar under cabinet lighting (basement)
- bathroom toe kick lighting
- master bathroom toe kick lighting
The location for the LV lighting panel is under the stairs on the main floor (in the center), so no LV run should be more than 30 feet or so.
https://magnitudeinc.com/products/constant-voltage-drivers/jb-series/
https://magnitudeinc.com/wp-content/uploads/2022/02/JBZN-SERIES-E-SERIES-Spec-Sheet-REV002-FINAL.pdf
I hope the price tags on the stuff you are looking at does not make you want to cry.
Walta
I've been sobbing for hours. However, anything multi-zone is expensive. Just buying 8 of the DiodeLED Lo-Pro enclosures is 8 x $60 = $480...plus then the cost of the transformers (which you can find less expensively). Plus the saved electrician time of installing a single box and quickly wiring rather than assembling each enclosure/transformer and wiring independently. Or my own time wiring everything...so it may come out not so bad of a premium.
Highly recommend Lee Valley Tools system of undercounter lighting found here: https://www.leevalley.com/en-ca/shop/hardware/lighting/led-tape-lighting
I bought the dimmable power supply and hard wired it into a junction box that I ran the old fluorescent lights wiring off of. Then used a normal dimmer switch for the lights. In between the lights I used 18 ga wire that was marine grade (left over from the boat!) Very happy with the results.