Quick answer: For 12V LED lighting, the right wire size depends on how many watts you're powering and how far the wire runs, not just on the fact that LEDs draw little power. Short runs to small loads can use 18 AWG. Longer runs or loads above about 30W usually need 16, 14 or 12 AWG. Use the chart below to keep voltage drop under about 3%.
You install a 12V LED strip along the kitchen cabinets. The end nearest the power supply looks great. The far end looks dimmer, or slightly orange.
Nothing is broken. The wire is too thin for the distance. At 12 volts, even a small loss in the wire is a big share of the total, and that's why wire size matters more for 12V lighting than most people expect.
12V LED wire size chart
Maximum one-way distance (in feet) from the power supply to the lights, for no more than 3% voltage drop at 12V:
| LED load | Current at 12V | 18 AWG | 16 AWG | 14 AWG | 12 AWG | 10 AWG |
|---|---|---|---|---|---|---|
| 12W | 1A | 28 ft | 45 ft | 71 ft | 113 ft | 180 ft |
| 24W | 2A | 14 ft | 22 ft | 36 ft | 57 ft | 90 ft |
| 36W | 3A | 9 ft | 15 ft | 24 ft | 38 ft | 60 ft |
| 48W | 4A | 7 ft | 11 ft | 18 ft | 28 ft | 45 ft |
| 60W | 5A | 6 ft | 9 ft | 14 ft | 23 ft | 36 ft |
| 96W | 8A | — | 6 ft | 9 ft | 14 ft | 23 ft |
Calculated for copper wire at room temperature, counting both the positive and negative conductors and assuming the whole load sits at the far end of the run. A strip whose LEDs are spread along the run loses less, so this chart is on the safe side. "—" means the current exceeds that wire's rated ampacity.
How to use the chart
- Add up your LED wattage. For strips, multiply watts per foot (or meter) by the length.
- Measure the one-way distance from the power supply to the lights, not the round trip.
- Find your wattage row and pick the thinnest wire whose distance is at least as long as your run.
Example: a 36W strip 20 feet from the power supply. 18 AWG only reaches 9 feet and 16 AWG reaches 15 feet, so use 14 AWG (24 feet).
Running a 24V system instead? You get 4× the distance
For the same wattage, a 24V system draws half the current, and the acceptable voltage drop (3%) is twice as many volts. Together, that means about four times the distance for the same wire.
| LED load | 18 AWG | 16 AWG | 14 AWG | 12 AWG |
|---|---|---|---|---|
| 24W | 56 ft | 90 ft | 143 ft | 227 ft |
| 48W | 28 ft | 45 ft | 71 ft | 113 ft |
| 96W | 14 ft | 22 ft | 36 ft | 57 ft |
Same assumptions as above, at 24V.
If you're planning long runs, a 24V system is often cheaper than buying thick 12V wire.
Why does voltage drop matter so much at 12V?
Every wire has a little resistance, so some voltage is lost along it. Losing 1 volt on a 120V circuit is under 1%. Losing 1 volt on a 12V circuit is about 8%, enough to visibly dim LEDs or shift their color.
Low voltage also means higher current for the same wattage, and the voltage lost in the wire rises with current. That's why 12V lighting needs thicker wire than the low power draw suggests.
For mains wiring, the US National Electrical Code includes a non-mandatory recommendation to keep branch-circuit voltage drop to about 3%, and 5% in total. We use the same 3% target for low-voltage LED runs.
Voltage drop vs. ampacity: two different limits
- Voltage drop is about performance: dim or uneven light at the far end. At 12V, this is usually the limit you hit first.
- Ampacity is about safety: how much current a wire can carry without overheating. For example, the NEC rates 18 AWG fixture wire at 6 amps and 10 AWG at 28 amps (EC&M on NEC Table 402.5).
Always check both: a wire can be safe for the current and still too thin for the distance.
Solid or stranded wire?
Both work for LED lighting.
- Stranded wire is more flexible and handles vibration better. It's the usual choice for vehicles, RVs, boats and anywhere the wire moves. Use connectors rated for stranded wire, or crimp ferrules on the ends.
- Solid wire is stiffer and holds its shape, which suits fixed runs inside walls or cabinets.
How to reduce voltage drop
- Put the power supply closer to the lights. Shortening the low-voltage run is the cheapest fix. See How to Power 12V LED Lights From a Wall Outlet.
- Use thicker wire for the run from the power supply to the lights.
- Feed long strips from both ends, or add a second feed partway along.
- Split the load into separate runs, each with its own wire back to the supply.
- Switch to 24V for long runs.
- Wire 12V lights in parallel, not series. See Parallel vs. Series Wiring for 12V Lighting.
Connecting the wires
- For joining and splitting low-voltage runs, WAGO 222 lever nut wire connectors accept solid or stranded wire from 28 to 12 AWG, with no twisting or soldering. (10 AWG needs a larger connector.)
- For plug-in power supplies and lights with barrel plugs, DC 2.1mm male and female wiring connectors let you connect bare wire to a standard barrel jack.
This guide covers the low-voltage DC side only. Mains (120V/230V) wiring, wire colors and cable sizes follow local electrical codes and differ between countries. Leave that side to a qualified electrician.
Frequently asked questions
What gauge wire do I need for 12V LED lights?
It depends on wattage and distance. As a rough guide at 12V: 18 AWG for small loads on short runs (for example, 12W up to about 28 feet), 16 or 14 AWG for typical strip installations, and 12 AWG or thicker for long runs or loads above 60W. Use the chart for your exact numbers.
Is 18 gauge wire OK for LED strip lights?
For short runs and small loads, yes. At 12V, 18 AWG keeps voltage drop under 3% for about 14 feet at 24W, but only about 9 feet at 36W. Beyond that, step up to 16 or 14 AWG.
What size wire for a 12V LED strip 20 feet from the power supply?
For a 24W strip, 16 AWG (22 feet) works. For 36W, use 14 AWG (24 feet). For 60W, use 12 AWG (23 feet).
Can wire be too thick for LED lights?
Not electrically. Thicker wire only reduces voltage drop. The practical limits are cost, stiffness and whether it fits your connectors and terminals.
Why is the far end of my LED strip dimmer?
Usually voltage drop. The wire or the strip itself loses voltage over distance. Use thicker feed wire, move the power supply closer, or feed the strip from both ends.
Does a 24V system need thinner wire than 12V?
Yes. For the same wattage and wire size, a 24V system can run about four times as far before reaching the same percentage voltage drop.
This guide is general information for low-voltage DC lighting. Turn off power before wiring, use wire and connectors rated for your current, and follow local electrical codes.
5 comments
Great article! Choosing the right size wiring for LED lighting is an important consideration to ensure optimal performance and safety. The appropriate wire size will depend on various factors such as the wattage of the LED lights, the distance between the lights and the power source, and the maximum current rating of the wire. It’s always best to consult with an electrician or follow the manufacturer’s recommendations to ensure that the wiring used is appropriate for the specific LED lighting application.
Stranded wire is more flexible than solid – that is why they make it stranded. The absolute reverse of what you have said. Also you have said that by arranging lots of led runs in parallel they will draw a lot of current through the wires, it’s the series linked runs that pull more current through the wires – for example: if you have 4 strips with 10 leds in parallel, each strip will only have the current draw for 1o leds, in series the current draw through those wires would be for 40 leds. Please correct me if I’m wrong, its been awhile since I’ve done Kirchoffs. I know I’m right about wire flexibility though – it is the main reason stranded wire was introduced.
Hi I brought the WS2812B 5 meter (60 led per meter) and I have a wire gauge question. I brought 18awg wire to connect the strip to the power source 5v 10 amp. I did this because I was told I need 18 awg wire to carry more than 8 amp current. But the WS2812B comes with thinner wire(20cms with a jst connector). I would like to keep the JST connector which makes it easy to connect/disconnect. Is it ok to connect the 18 awg wire to thin wire of WS2812B or do I need to cut your wire off and attach/solder 18 awg wire directly to the WS2812B?
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I plan to drill my corner shower canopy and install some 12 volt marker LED lights like what goes on vehicles. I will install at least 20- to 40 of these and wondered what watt remote control i should use. Would a 120 watt relay control be ok for up to 60 of these bulbs as they are about .o3 amps or .04 each. If i can find the voice control for four different color lights i might try the wifi approach but i think i need some advice on that how to set it up economically.