Quick answer
An LED driver is the electronic power supply that converts household alternating current into the regulated direct current an LED light needs, holding either the current or the voltage steady so the LEDs run at the right brightness without overheating.
Screw-in LED bulbs hide a tiny driver in the base, while fixtures, tape lights and under-cabinet lights often use a separate driver box. The driver usually decides how well a light dims and how long it lasts.
Quick facts
The key facts about LED Driver, with sources:
- Input
- Household AC, for example 120 V in US homes
- Output
- Regulated DC: a fixed current (constant current) or a fixed voltage such as 12 V or 24 V (constant voltage) 12
- Example efficiency
- Mean Well LPV-60: 76% at 5 V up to 86% at 24–48 V (typical) 1
- Example rating
- Mean Well HLG-120H-C: 150 W constant current, 94% typical efficiency 2
- Class 2
- Power-limited output; the LPV-60 is listed as a Class 2 power unit 1
- Energy context
- DOE: an LED as low as 9 W can give the 1,100 lumens of a 75 W incandescent 5
Key takeaways
- Every LED light has a driver; in a bulb it is hidden in the base.
- Constant-current drivers feed a set current to LED modules; constant-voltage drivers feed 12 V or 24 V to tape and strips.
- The driver, not the LED chip, usually decides how a light dims and often how long it lasts.
- Match the driver to the LEDs’ type, voltage or current, and wattage, and to the dimmer.
- Driver boxes connect to 120 V wiring; replacing one is work for an electrician.
What an LED driver does
LEDs run on low-voltage direct current at a controlled current. Your home supplies 120-volt alternating current, and the driver sits between the two to do the conversion.
A driver also protects the LEDs. An LED’s current climbs fast if its voltage rises a little, and heat makes that worse. A driver holds the current or voltage steady, so the light stays even and the chips do not overheat.
People sometimes call it an LED transformer or ballast, words borrowed from older lighting, but a modern driver is a switching power supply, closer to a phone charger than to a transformer.
How a driver turns wall power into LED power
Inside, the driver rectifies AC into DC, then uses a fast-switching circuit to set the output. A feedback loop watches the output and adjusts it many times a second.
Many drivers also correct the power factor, which keeps the current drawn from the wall in step with the voltage.
Mean Well’s HLG-120H-C, for example, lists a power factor of 0.98 or better at 115 V and full load 2.
Every conversion loses a little energy as heat. Mean Well’s LPV-60 constant-voltage driver lists typical efficiency from 76% on its 5 V model to 86% on its 24, 36 and 48 V models 1. The larger HLG-120H-C lists 94% 2.
- 120 V AC inFrom the branch circuit
- RectifierTurns AC into DC
- Switching converterSets the output voltage or current
- Feedback and protectionHolds output steady; limits shorts and overloads
- Regulated DC outTo the LED module, bulb or tape
Source: [2]
Constant current vs constant voltage
| Type | What it holds steady | Typical use | Example |
|---|---|---|---|
| Constant current (CC) | Output current; voltage floats within a range | LED modules in downlights, high bays, outdoor fixtures | HLG-120H-C: 150 W, constant current 2 |
| Constant voltage (CV) | Output voltage, such as 12 V or 24 V | LED tape, strip and under-cabinet lights | LPV-60: 5 to 48 V models, 60 W 1 |
| Integral (in-bulb) driver | Built into a screw-in bulb | Household LED bulbs | Not replaceable on its own |
| Dimmable driver | Responds to a dimmer or control signal | Dimmed rooms and fixtures | Phase-cut, 0–10 V and other inputs |
Example: sizing a constant-voltage driver for under-cabinet tape
An illustration using the published ratings of the Mean Well LPV-60-24 1. The tape figure is hypothetical; read your tape’s own label.
| Step | Math | Result |
|---|---|---|
| Driver rating | LPV-60-24: 24 V, 2.5 A | 60 W |
| Tape load (hypothetical label) | 12 feet × 4.4 W per foot | 52.8 W |
| Headroom | 52.8 W ÷ 60 W | About 88% of the driver’s rating |
| Energy from the wall at 86% efficiency | 52.8 W ÷ 0.86 | About 61 W drawn |
Many designers leave headroom so a driver is not run at its limit; follow the fixture or tape maker’s guidance. The lighting circuit planner helps group lights on circuits.
Where you find LED drivers in a home
In screw-in bulbs, the driver is inside the base. In recessed downlights it is often a small box on the fixture or a module behind the trim.
Under-cabinet, cove and tape lights use a separate constant-voltage driver, often hidden in a cabinet or junction box. Outdoor and landscape lights use weather-rated drivers; the LPV-60 is encapsulated to IP67 1.
Some smart switches and dimmers rate LED loads separately from incandescent loads because LED drivers behave differently on a switch.
What a good driver gives you, and what a poor one costs you
Good driver
- Steady light without visible flicker.
- High efficiency, so less heat; 94% on the HLG-120H-C 2.
- Short-circuit and overload protection 2 1.
- Smooth dimming with a compatible control.
Poor or mismatched driver
- Flicker, buzzing or poor dimming.
- Heat that shortens the life of the driver and LEDs.
- Wrong output type can destroy LEDs.
- Early failure, often before the LEDs themselves.
Limits to keep in mind
A constant-voltage driver must not feed a constant-current LED module, and the reverse is also true. Match the type and the exact rating on the fixture or tape label.
Heat shortens driver life, and drivers in closed cabinets or under insulation run hotter, so follow the maker’s temperature rating.
Dimming is not automatic: a driver dims only if it is designed to and only with compatible controls. Mean Well’s dimmable HLG “B” versions take a 1–10 V DC signal, a 10 V PWM signal or a resistance, not a wall phase-cut dimmer 2.
Driver vs transformer
An old magnetic transformer only steps voltage down. An LED driver also regulates current or voltage and protects the LEDs. Do not swap one for the other without checking the fixture label.
What drives the cost and lifespan
We do not print prices, but cost rises with wattage, outdoor rating, dimming features and efficiency. Labor depends on whether the driver is reachable through a fixture opening or hidden in a ceiling. The project cost tool lists drivers of cost.
Warranty terms vary by maker; Mean Well lists a two-year warranty on the LPV-60 1. Lifespan depends heavily on operating temperature.
Energy savings are real: DOE says an LED as low as 9 watts can give the 1,100 lumens of a 75-watt incandescent 5.
As an example at the EIA’s July 2026 average residential price of 18.31 cents per kWh 6, a light used 3 hours a day saves about (75 − 9) W × 3 h × 365 ÷ 1,000 × $0.1831 ≈ $13 a year.
How a driver is chosen and replaced
Drivers connect to 120 V wiring, so choosing and replacing one is work for a licensed electrician.
- Read the fixture or tape label: CC or CV, voltage or current, and watts.
- Choose a listed driver with the right output, enough headroom and the right dimming input.
- Check location: damp, wet or outdoor ratings where needed.
- With the circuit off and verified dead, the electrician wires the driver in an approved enclosure.
- Test full brightness and dimming across the range.
Care and owner checks
- Keep drivers ventilated; do not bury them under insulation or storage.
- Note when flicker starts and what changed (new bulb, new dimmer).
- Replace bulbs with the same model so the dimmer and driver stay matched.
- Switches and covers near drivers should stay cool to the touch 7.
Warning signs of a failing driver
Common signs: flicker that gets worse over time, lights that turn on late or cycle on and off, buzzing from the fixture, partial brightness, or a burning smell. A swollen or discolored driver case means it is overheating.
Standards that apply
UL 8750 is the US safety standard for LED equipment used in lighting products. UL announced its first edition in 2009 4.
Intertek, a testing lab, describes it as covering LED drivers and power supplies, including constant-current and constant-voltage types, and notes it is used alongside UL 1598, the standard for complete luminaires 3.
Mean Well lists UL8750 among the safety standards for the HLG-120H-C 2.
Class 2 power units limit output energy, which affects how the low-voltage wiring may be run. The LPV-60 data sheet lists it as a Class 2 power unit 1. Installation falls under NFPA 70 as adopted locally.
LED driver compared with related parts
| Part | Job | Relation to the driver |
|---|---|---|
| Dimmer switch | Sets brightness from the wall | The driver must understand its signal |
| Transformer | Changes AC voltage | Does not regulate LED current |
| LED module or tape | Makes the light | Needs a driver matched to its CC or CV rating |
| Smart switch | Remote or automated control | Rates LED loads separately |
Myths about LED drivers
- Myth LEDs last forever.
- Reality Drivers often fail first, and heat shortens both.
- Myth Any 12 V power supply can run LED tape.
- Reality Use a listed LED driver rated for the load and location.
- Myth All LED drivers dim.
- Reality Only dimmable drivers do, and only with compatible controls 2.
- Myth A higher-watt driver forces more power into the LEDs.
- Reality A CV driver supplies only what the load draws; a CC driver must match the module’s current.
Code edition and lighting rules
What to do with a flickering LED light
Start with the simple causes, such as a new bulb or a new dimmer, before replacing parts.
- If Started after a new bulb
- Then Swap back or use a bulb on the dimmer’s list
- If Only at low dimmer settings
- Then Ask about a compatible dimmer or low-end trim
- If Fixture buzzes, cycles or smells hot
- Then Turn it off; call an electrician to replace the driver
- If Many lights flicker together
- Then Call an electrician; it may be a wiring or neutral issue
Photograph the label
Before calling, take a photo of the driver or fixture label. CC or CV, voltage, current and watts are what the electrician needs.
Questions about LED Driver
Do all LED lights need a driver?
Yes, because every LED needs regulated DC power. In screw-in bulbs the driver is built into the base, while fixtures, tape and strip lights often use a separate driver box.
What is the difference between constant current and constant voltage drivers?
A constant-current driver holds the current steady and lets the voltage vary; it powers LED modules rated in milliamps. A constant-voltage driver holds a fixed voltage, such as 12 or 24 volts; it powers LED tape and strips. Use the type the light is labeled for.
How do I know if my LED driver is bad?
Flicker that worsens, lights that start late or cycle on and off, buzzing, partial brightness or a burning smell are common signs. Turn the light off and have an electrician check the driver.
Can an LED driver cause flickering?
Yes. A failing driver, or one that does not match the dimmer, is one of the most common causes of LED flicker. Check that the light and dimmer are on each other’s compatibility list first.
Is an LED driver the same as a transformer?
No. A transformer only changes AC voltage, while an LED driver converts AC to DC and regulates current or voltage to protect the LEDs. Some low-voltage lights need a driver, not a transformer.
How efficient are LED drivers?
It depends on the model and output voltage. One Mean Well constant-voltage family lists typical efficiency from 76% at 5 volts to 86% at 24 volts and above. A larger constant-current model lists 94%.
Can I use a bigger driver than I need?
For constant-voltage drivers, a higher watt rating at the same voltage only supplies what the load draws. For constant-current drivers, the current must match the LED module. Follow the fixture label.
What does Class 2 mean on a driver?
It means the output is power-limited by design, which lowers fire and shock risk on the low-voltage side and affects how its wiring may be run under the electrical code.
How long do LED drivers last?
There is no single figure, because lifespan depends on quality, load and especially temperature, and many drivers fail before the LEDs do. Warranties vary; one Mean Well model lists two years.
Can I replace an LED driver myself?
The driver connects to 120-volt wiring, so replacement is electrical work and this site does not give DIY wiring steps. A licensed electrician can match and install the right driver.
Sources
- Mean Well, LPV-60 series 60W single output LED power supply specification, retrieved .
- Mean Well, HLG-120H-C series 150W constant current mode LED driver specification, retrieved .
- Intertek, UL 8750 Standard for LED Equipment for Use in Lighting Products, retrieved .
- UL, UL publishes first safety standard for LED lighting products and components (2009), retrieved .
- US DOE Energy Saver, Consumer Guide to Energy-Efficient Lighting (DOE/EE-2465), retrieved .
- US EIA, Electric Power Monthly Table 5.6.A, average retail price to ultimate customers by end-use sector, retrieved .
- US CPSC, Home Electrical Safety Checklist (Pub 513), retrieved .
- Texas Department of Licensing and Regulation, 2023 National Electrical Code is almost here, retrieved .
- Washington State Register WSR 25-23-069 (L&I adopts the 2026 NEC), retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Driver ratings, efficiency, power factor, Class 2 and warranty come from Mean Well LPV-60 and HLG-120H-C specifications. UL 8750 scope comes from UL’s 2009 release and Intertek.
Lumen and wattage figures are from DOE; the savings example uses EIA’s July 2026 residential price and is labeled as an example. No DIY wiring; no installation prices under G-COST.
Suggest a correction. We fix errors and say what changed.