LED Drivers: What Are They And Which Do I Need?

The switch to LED lighting technology is trending tremendously in the commercial industry. Due to their long-life spans and energy-efficiency, many contractors are beginning to understand the benefits of this light-emitting diode. Learn more about LED’s with The Only LED Guide You Will Ever Need

…So, how do you power LED’s?

Because LED’s operate with a low voltage, they require specialized equipment to power them. LED light fixtures require a specialized device called an LED driver. These drivers provide LED light bulbs with the electricity to function properly; similar to how a ballast powers a fluorescent lamp or a transformer powers a low-voltage incandescent bulb.

LED Driver Header

How do LED drivers work?

External LED Driver

LED Drivers basically keep the electrical current flowing through the LED circuit at their rated level of power. LED’s are designed for low voltage power (12-24 volts), but in most commercial spaces the supply of power is much higher (120-277 volts).

LED drivers are used to direct the right amount of electricity to the lightbulb. In the instance of a change in voltage (power), an LED driver would protect an LED bulb from any electrical current fluctuations. These fluctuations can cause a light bulb to vary its light output (brightness), or cause the LED bulb to overheat. An LED Driver is vital to the safety of the bulb.

Internal vs. External Drivers

Every LED light fixture requires an LED driver to power them. There are two different types of devices: internal drivers and external drivers.

Household lightbulb

Internal Drivers

Internal drivers are normally found in household light bulbs. These are your standard incandescent and CFL light bulb replacements with screw-in or plug-in capabilities.

Outdoor Lightin

External Drivers

External drivers are normally used for commercial lighting purposes. This is anywhere from area lighting, to warehouse lighting, to street lighting. In most cases, it’s much cheaper to replace the external driver than to replace the entire LED light fixture. For lighting installation, check out our Retrofit Guide

When should I replace my External Driver?

Replacing External Driver

It’s no surprise that external drivers will fail, but before replacing your entire LED light fixture, you should consider the benefits of simply replacing your external driver. Often times, drivers will fail due to their exposure to high temperatures.

These high internal temperatures can shorten the life of the driver, and cause an LED light bulb to stop working. Just by replacing your old driver with a new one, you can save time and money!

How do these high temperatures occur?

The temperature within an LED driver directly correlates with the external temperature of the driver. High temperatures occur when the electrolytic capacitors found inside of the driver, begin to overheat.

These capacitors have a gel inside them that gradually evaporates over time. When exposed to higher temperatures, the gel evaporates quicker, and causes the driver to stop working unexpectedly. An LED driver will indicate its hottest point on the label, known as the TC point.

This point is used to mark a driver’s max operating temperature. This is why LED drivers with high TC points can withstand higher temperatures, and therefore have higher life expectancies. If your LED light bulb has stopped working unexpectedly, it probably means that it is time to replace your external driver.

What External LED Driver do I need?

There are three types of external drivers, constant-current, constant-voltage, and AC LED drivers. When replacing an old driver, you must make sure that the input/output requirements match perfectly with your LED lamp. LED’s cannot operate with conventional transformers like low-voltage halogen or incandescent bulbs. Because they operate with a low-voltage, they require a specialized device that can detect low voltages.

Constant- Current Drivers

Constant Current Driver

Constant-current external drivers will power LED’s with a fixed output current and an array of varying output voltages. A particular LED bulb will indicate one specific current, labeled in amps, and will have a variety of voltages that will vary depending on the wattage of the bulb. These specs can be found on the external driver’s datasheet.

Constant-Voltage Drivers

Constant Voltage Driver

Constant-voltage external drivers will power LED’s with a fixed output voltage and a maximum output current. In this particular LED light bulb, the maximum current is already regulated within the lamp, and the voltage will be fixed at either 12V DC or 240V DC. These specs can be found on the external driver’s datasheet.

A/C LED Drivers

A/C LED External Drivers

A/C LED drivers are used with bulbs that already contain an internal driver. The internal driver will convert the electrical current from A/C to DC.

An A/C LED Driver simply detects the voltage of an LED bulb and converts the electrical current to meet the requirements of the power for that particular lighting device. These LED drivers are typically found in LED MR16 bulbs, but they can be used with any 12-24V A/C LED bulb.

Other things to consider when purchasing an external LED driver

Max Wattage

Max Wattage

LED drivers should always be paired with LED bulbs that use 80% of their maximum rated wattage. For example, if your external driver can operate a maximum of 120 watts, it should only operate LED light bulbs that use 96 watts.

120 watts x 0.80 = 96 watts




All three types of external drivers offer dimming capabilities. Be sure that both the LED lightbulb and the driver indicate that they have dimmable functions on the product data sheet. Most dimmable external drivers will require an external lighting control system. These devices will specify what external dimmer is needed to control certain LED bulbs.  Learn how to Install dimmers and sensors with our Lighting Control Guide.

UL Listing

Class I vs. Class II

UL Class II drivers comply with the UL1310 standard. This means that the power output is safe for contact and no major safety protection is required for handling. (There is NO risk of fire or electric shock)

These drivers can operate with:

  • Less than 60 volts in dry applications
  • 30 volts in wet applications
  • Less than 5 amps
  • Less than 100 watts

Please Note *There is a restriction on how many light bulbs can operate on one class II driver*

UL Class I drivers have a power output that ranges outside of Class I drivers. Due to their high voltage output, Class I drivers require safety protection when handling them. Unlike their counterpart, Class I drivers are far more efficient because they can accommodate more LED light bulbs.


We strive to provide quality products at competitive prices. Whether you are looking to replace or retrofit your lighting system, we can help you along the way. HomElectrical offers an array of LED Drivers and LED Lighting for your convenience.

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Shakir Williams
Shakir Williams

A true creative with a penchant for the spiritual and natural order. She loves the Earth, almost as much as she loves writing about it.

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