What Kind of Wire Do You Use for Under Cabinet Lighting?

What Kind of Wire Do You Use for Under Cabinet Lighting?

For a typical 12V or 24V single-color LED setup, 18 AWG two-conductor copper cable is a useful starting candidate for a short, modest-load run—if the light, driver, connectors, and installation route permit it. A short, lightly loaded connection may allow 20 AWG; a longer run or a feed carrying several lights may call for 16 AWG. These are options to check, not universal prescriptions. For a complete plug-in kit, use its supplied leads. For a direct-wire fixture connected to the household circuit, the answer is a different, circuit-rated wiring method rather than 16–20 AWG LED hookup cable.

The decision is easier once you separate the household side of the power supply from the low-voltage side feeding the lights. The sections below show which cable types belong to each job and how to decide whether a common gauge is appropriate.

Which Type of Wire Fits Your Lighting Setup?

Plug-in kit: its adapter, leads, and connectors are meant to work as a system. If the supplied lead reaches, there is no separate gauge to choose. If it does not, look for a manufacturer-approved extension rather than splicing in whatever cable is at hand. The transformer and LED driver guide explains why the power supply is part of this decision.

Custom 12V or 24V LED installation: use cable specified or permitted for the light and driver. A single-color light often uses a two-conductor positive/negative connection, commonly described as 18/2 or 16/2 when those gauges fit the run; tunable-white or color-changing products may need more conductors or proprietary connectors. Match the conductor count, voltage, terminals, and cable rating to the actual equipment.

Hardwired household-circuit fixture: this is not a job for small LED hookup wire. Residential branch circuits may use a cable assembly such as NM-B in suitable dry locations, while individual building-wire conductors such as THHN/THWN are used within an appropriate wiring method. They are not interchangeable names for “under-cabinet wire.” Southwire's NM-B specifications describe its branch-circuit use and limits. Have a qualified electrician choose the method for the actual circuit, fixture, and local requirements.

20, 18, or 16 AWG: Where Each Can Fit

For low-voltage LED cable, a smaller American Wire Gauge (AWG) number means a thicker conductor: 16 AWG is thicker than 18 AWG, and 18 AWG is thicker than 20 AWG. Thicker wire can reduce voltage lost along a run, but size alone does not establish that a cable is rated for its route or fits the light's connector.

These are candidate sizes for the low-voltage side only, not ampacity ratings or a substitute for the product's installation instructions. As the driver moves farther away or more lights share one feed, recheck the size. Lutron's constant-voltage driver guidance identifies load, lead length, and gauge as the main variables behind voltage drop—the loss of voltage along a wire. A lower-voltage system also draws more current than a higher-voltage one at the same wattage, so do not reuse a 24V cable decision for a 12V setup without checking it again.

How to Choose a Size for Your Actual Run

1. Check the light and driver: confirm the output voltage, connector type, permitted cable or extension, and any maximum run-length chart.
2. Add the load on the cable you are sizing: four 6-watt lights on one feed total 24 watts. That is about 2 amps at 12V or 1 amp at 24V (watts ÷ volts). A separate branch to one light carries less than the shared feed.
3. Measure the routed distance: follow the path from driver to light through the actual cabinet layout, not a straight line across the countertop. Include connections between linked fixtures where the manufacturer says they count.
4. Compare the approved gauges: find a size that meets the product's distance and load limits, fits the connector, and is rated for the planned installation route. If none does, move the driver closer or have the system redesigned rather than guessing.

A real chart example: for one specific Lutron Lumaris 24V linear-lighting system, the installation instructions list maximum wire lengths of 16.5 feet for 20 AWG, 32.8 feet for 18 AWG, and 49.2 feet for 16 AWG. On a 20-foot run in that system, 20 AWG exceeds its published limit while 18 AWG is within it. Its chart also counts wiring between linked luminaires. This demonstrates how to read a manufacturer's table; those distances are not universal limits for other LED strips, bars, or pucks.

A gauge calculation is not the whole decision. If lights dim toward the far end, flicker, or a connector feels warm, switch off the system and inspect it against the product instructions; a loose connection or unsuitable control can also be involved. Do not simply install a larger power supply to hide a wiring problem.

Before You Route the Cable

A low-voltage cable that carries 12V is not automatically suitable for every location. Check its marking and the light manufacturer's instructions before passing it through cabinetry or concealing it in a wall. If you are considering spare audio cable, see Can You Use Speaker Wire for Under Cabinet Lighting? for that separate rating question.

For a new hardwired household feed, the electrician must select the appropriate circuit cable or wiring method for the fixture and location. Our hardwired installation guide covers the planning sequence and safe stop points.

Multiple fixtures: the first feed from a driver may carry the combined load, while later branches carry less. Connector ratings, driver capacity, and whether the product permits linking matter alongside gauge. For fixture-to-fixture linking, see Can I Daisy Chain Under Cabinet Lights?. Do not alter a factory wiring harness or mix line-voltage and low-voltage wiring in one enclosure or route unless the equipment instructions and a qualified installer allow it.

If you would rather avoid selecting a separate cable, a complete kit is often the simpler purchase. For example, Lumaz's Ultra-Thin LED Puck Light Kit for Under Cabinet uses 12V DC pucks with a matching plug-in adapter and hidden-touch control. It is a fit when its supplied lead reaches your planned positions; check the kit configuration and wiring instructions before buying rather than assuming its leads can be extended.

Common Questions

Is 18-gauge wire enough for under-cabinet LED lights?

Often it is a reasonable candidate for a compact low-voltage installation, but check the manufacturer's distance and load limits, connector fit, and installation route. It is not a substitute for household circuit cable.

Should I use 16-, 18-, or 20-gauge wire?

For a custom low-voltage connection that permits field wiring, compare 18 AWG first, see whether the product allows 20 AWG for a short/light run, and consider 16 AWG for a longer or more loaded feed. Confirm the manufacturer's chart and the cable and connector ratings before choosing. Use the supplied wiring if you bought a complete kit.

Can I install the cable myself?

Using a supplied plug-in kit and accessible factory connectors is different from adding concealed wiring or changing a household circuit. Follow the kit instructions for user-accessible parts. For new hardwired feeds, concealed runs, uncertain cable ratings, or a circuit you cannot identify, consult a qualified electrician and local requirements before work begins.