Glance around your home and you’ll notice most light fixtures connect directly to the line voltage of your electrical system. Line voltage, also called high voltage or household current, is the standard 120 volts found in outlets and junction boxes in the U.S. Line voltage fixtures cover most traditional lighting, including ceiling fixtures and sconces.
Low voltage lighting runs on far less, typically 12 or 24 volts. It got its start in American homes in the 1950s, developed first for landscape lighting before moving indoors. Today it’s common in recessed lighting, track lighting, under cabinet lighting, strip and tape lighting and more.
So what sets low voltage lighting apart, and when should you choose it?
What Counts as Low Voltage?
In general electrical usage, anything under 50 volts gets called low voltage. The code is more specific.
NEC Article 411 covers lighting systems operating at 30 volts or less, with power supply output circuits rated for no more than 25 amperes and supplied from a maximum 20 ampere branch circuit. Article 725 governs the Class 2 wiring, capping those circuits at 30 volts and 100 volt amps.
One detail explains a lot about landscape lighting. Where a system is used outdoors or anywhere wet contact could occur, the voltage limit drops to 15 volts. That’s why nearly every landscape system you’ll see runs at 12V rather than 24V.
The Class 2 classification is also why low voltage is easier to install. Article 725 allows Class 2 wiring to run without conduit in many cases, along structural members and through framing cavities, which line voltage conductors can’t do. Local amendments can override that, so check with your inspector.
Transformers and Drivers
Low voltage LED fixtures rely on transformers, sometimes called drivers or power packs, to step the line voltage down from 120 volts. The driver either lives inside the fixture or sits remotely.
LED drivers do two jobs:
- Convert higher voltage alternating current to low voltage direct current.
- Protect the LEDs from voltage and current fluctuations. LED output is proportional to current supply, and LEDs are rated to operate within a specific current range. Too much or too little current makes output vary or degrade faster as heat builds inside the LED.
Every LED light source depends on a driver, internal or external.
When sizing one, use only about 80% of the rated load of the power supply. That keeps the driver from running stressed and extends its life. A driver rated at 96 watts should carry no more than 77 watts of LEDs (96 × 0.8 = 76.8). Drivers often have a minimum load too, below which the LEDs flicker or hum, so check both ends of the range.
Household bulbs with screw-in or plug-in bases normally have an integrated driver, which is what makes them easy to replace. LED downlights, tape lights, and many panels and outdoor rated fixtures need an external driver. Sometimes a fixture ships with the driver it needs and sometimes it doesn’t, so check the recommended accessories on the product page or the manufacturer’s spec sheet before you order.
Constant Voltage vs Constant Current
Two driver types, and they aren’t interchangeable.
Constant voltage drivers hold a fixed output, usually 12V or 24V, and let the load draw the current it needs. This is what tape light, strip light and most linear products use, and it’s why you can cut tape to length without changing the driver.
Constant current drivers hold a fixed current, expressed in milliamps, and vary the voltage to suit. Many LED downlights, modules and engines use these, and the driver has to be matched to that specific fixture.
Putting a fixture on the wrong driver type produces flicker, dim output or a failed driver. If a spec sheet lists an output in mA, it’s constant current. If it lists 12V or 24V, it’s constant voltage.
12V or 24V?
Both are common and the choice comes down to run length.
Power equals volts times amps, so a 24V system draws half the current of a 12V system for the same wattage. Less current means less voltage drop across the wire, which means you can run longer before the far end of the run goes dim.
As a rough guide, choose 12V for landscape lighting, where the 15 volt wet location limit applies, and for short indoor runs. Choose 24V for longer tape light runs, whole room installations and anywhere you’re pushing distance.
Voltage Drop: The Thing That Trips People Up
This is the most common reason a low voltage install disappoints, and most buying guides skip it entirely.
Voltage falls off across the length of a wire run. The first fixture gets full voltage and the last one gets less. On a 12V system that margin is thin, because a drop that would be trivial on a 120V circuit is a significant percentage of 12 volts.
Keep every fixture within 10% of the source voltage. On a 12V system, nothing should sit below 10.8V. Below that, LEDs visibly dim and some shift color.
Three ways to manage it:
- Heavier wire. Use 12 AWG rather than 14 AWG as your default on landscape runs, and step up to 10 AWG past roughly 150 feet.
- A multi tap transformer. Feed a long run off the 13V or 14V tap to offset the drop before it happens.
- Split the load. Two shorter runs from the transformer beat one long one, and a second transformer closer to distant fixtures beats both.
Measure voltage at the last fixture before you bury cable or close up a wall. It takes five minutes and it’s the difference between a working install and digging a trench back up.
Types of Low Voltage Lighting
There are plenty of ways to use low voltage around a home. Under cabinet and cove lighting works in kitchens, closets and bathrooms to light countertops, shelving and surfaces. Low voltage recessed lighting handles general illumination indoors and out, or directional light to highlight a feature. In many cases low voltage does the same job in the same space as line voltage.
Outdoors, most people choose low voltage for the installation alone. Nearly all landscape and path fixtures come in low voltage, and adding or moving one is easy because there’s no trenching to conduit depth. Line voltage outdoor installations usually mean hiring an electrician, since the wiring has to run in conduit buried to code depth.
Spotlights, well lights and step lights add illumination around a home’s exterior. LED string lights, or bistro lights, are another popular low voltage effect on trees and over patios.
Dimming Low Voltage
This is where budgets get away from people, and the original version of this article glossed over it.
A standard incandescent dimmer will not work with low voltage. You need a dimmer matched to the transformer type: MLV for magnetic transformers, ELV for electronic ones. Mismatch them and you get flicker, buzzing or a dimming range that quits at 30%.
Those dimmers cost more than a standard one, and that’s worth putting in the budget alongside the transformers rather than discovering it at the end. If you’re troubleshooting an existing system, our guide to what causes LEDs to flicker covers the transformer and dimmer interactions in more detail. You can also browse Lutron dimmers including MLV, ELV and 0-10V options.
Bottom Line
Line voltage and low voltage both have their place, and the choice usually comes down to installation and fixture cost. Line voltage is often closer to plug and play, and the fixture itself can be cheaper.
On energy, the honest answer is clearer than it used to be. Low voltage doesn’t save energy over line voltage. A transformer has conversion losses, so a low voltage system is marginally less efficient at the wall than an equivalent line voltage LED. The savings people associate with low voltage come from LED versus incandescent, not from the voltage. Choose low voltage for the installation flexibility and the fixture sizes, not for the power bill.
What we can’t say strongly enough is to use a dimmer wherever possible. Dimmers give you control over light levels, with aesthetic and financial benefits on either system.
Where low voltage genuinely wins is size. Smaller fixtures open up tight, hard to reach spaces that line voltage can’t serve. Think super slim LED downlights, puck lights, well lights and strip lighting inside recessed slot details.
Whether you’re lighting a kitchen with under cabinet fixtures or brightening the walkway to your front door, PROLIGHTING carries plenty of low and line voltage options. Our certified lighting PROs can help with fixture selection, layouts, quotes and product questions, including sizing a transformer and checking voltage drop on a long run. Send us an email or use the live chat on our site. We’re available Monday through Friday, 8AM to 5PM EST.
Updated September 2026
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