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Increase Lighting Efficiency with LED Drivers and Fluorescent Ballasts

12/4/23

Lighting accounts for 17% of total electricity consumption in commercial buildings, according to the most recent study from the U.S. Energy Information Administration. To cut down on energy costs and meet new federal standards, facility managers are replacing old incandescent fixtures with high-efficiency lighting technologies, like light emitting diodes (LEDs). New lighting can be 10 times more efficient than incandescent bulbs, as well as requiring less maintenance and emitting less waste heat. However, installing LEDs isn’t as easy as swapping out bulbs. To get the longest life and best performance out of your high-efficiency lighting fixtures, they will need to be paired with the right ballast or driver. 

Why Drivers and Ballasts are Necessary

Unlike incandescent bulbs, LEDs and fluorescent lights cannot run on the electrical current from a standard outlet. LEDs require low-voltage direct current, while fluorescents need a high-voltage impulse to ignite, followed by a low-voltage, high-frequency alternating current. To transform the electrical current flowing from the outlet into a form that can be used by your lights, you will need an electronic ballast or driver.

Upgrading ballasts and drivers can improve your lighting’s performance and efficiency. Some common reasons to replace ballasts and drivers include: 

  • Light quality: Old fluorescent ballasts can flicker and hum. New electronic ballasts are quieter and create constant illumination. 
  • Dimmability: The ability to dim the lights when full brightness isn’t needed can cut your energy usage and create a more welcoming atmosphere. 
  • Controllability: Drivers and ballasts that are compatible with building automation system occupancy sensors can reduce energy costs and allow easier control over a room’s appearance. 

Fluorescent Ballast Basics

Fluorescent lights work by creating an arc inside a glass tube filled with fluorescing gas. To generate that arc, the light relies on the current from its ballast. A ballast transforms the 120 or 277 volts in your building’s electrical supply into a brief high-voltage ignition spark, followed by a low-voltage, high-frequency current that maintains the bulb’s arc.

Choosing the right ballast depends on how you want your lighting to perform. Some features to look for in a fluorescent ballast include:   

  • Compatibility: Ballasts are designed to work with a specific number and type of fluorescent bulbs, so be sure the ballast will work with your fixture. A ballast designed for T5 bulbs may not work with longer T8 bulbs.  
  • Harmonic distortion: Like all electronic devices, fluorescent ballasts distort the alternating electrical current flowing in your building. This distortion can affect the performance of other electrical devices in your facility. Ballasts are rated by total harmonic distortion, which can range from 32% to less than 10%.  
  • Efficiency: Ballasts come in a range of energy output levels, called the “ballast factor.” A ballast with a high factor will produce brighter light but use more energy. Ballasts are also rated for their power factor, or how efficiently they transform current. Upgrading to higher power factor ballasts can reduce energy costs without sacrificing performance. 
  • Quick startup: An electronic ballast can ignite the arc inside its fluorescent tube using one of three methods: 
    • Instant start ballasts produce a voltage spike that immediately generates a full-brightness arc inside the lamp, without any flickering or warmup period. However, instant starts are hard on the fluorescent bulb’s electrodes, and they can limit a bulb’s lifespan to 10,000 switching cycles. A T8 fluorescent tube can be expected to burn 24,000 to 30,000 hours with an instant start ballast, so 10,000 switching cycles should be plenty for overhead lights that are turned on in the morning and burn all day.  
    • Rapid start ballasts heat the bulb’s electrodes before firing, reducing the voltage needed to ignite the arc. They can have a delay of up to a second before lighting up, and they produce about 2 watts of waste heat per bulb during operation. Compared to instant start ballasts, using rapid start ballasts can extend the bulb’s lifespan by 5,000 to 10,000 switching cycles.
    • Programmable rapid start ballasts heat the bulb’s electrodes with greater precision. While they have a delay of between 1 and 1.5 seconds before lighting up, the programmable rapid start ballast can extend a bulb’s lifespan to 50,000 switching cycles, as well as leading to a longer total lifespan of 40,000 hours for a typical T8 bulb. 
  • Light quality: Modern electronic ballasts generate a high-frequency current, which is more efficient and eliminates the flickering that can plague old fluorescent lights. New ballasts can also be quieter, emitting less annoying buzz. Ballasts are given a noise rating of “A” through “D,” with A being quietest.
  • Dimming: Not all ballasts can dim the lights. Choosing a dimmable ballast can enable occupants to save power by turning the lights down when full brightness is not required.  
  • Controllability: Some electronic ballasts are designed to interface with building automation software, allowing remote control over their operation. Controllable ballasts can be integrated with technologies like occupancy sensors and daylight harvesting schedules to further improve the light’s efficiency. 

LED Driver Basics

An LED driver transforms the high-voltage alternating current in your building’s power supply into a low-voltage direct current. Some drivers simply supply a fixed output, while others are dimmable and can interface with occupancy sensors and building automation software. When choosing a driver, consider the following features: 

  • Input and output current: First, be sure the driver will be able to connect to your building’s power supply and generate the current needed by your lighting. A driver's output can vary in voltage, amperes and watts, depending on the type of LEDs they are designed to power. Many drivers have programmable output levels, allowing them to work with a range of fixtures.
  • Harmonic distortion: Like fluorescent ballasts, LED drivers are electronic devices that draw irregularly from your building’s power supply, which can disturb the frequency of your alternating current. Drivers are rated by total harmonic distortion, with higher ratings creating more distortion. 
  • Insulation level: Some high-powered LED drivers are Class 1 electrical devices, carrying fire and electrocution risks. They must be well insulated and handled with care. Class 2 drivers emit a low voltage output, which carry less risk and require minimal insulation. 
  • Dimming method and type: Not all drivers are dimmable, and not all dimmable drivers use the same input. For example, a 0-10v dimming method relies on a low-voltage signal that comes to the driver via a dedicated circuit. Drivers also vary in their dimming range. Some drivers can be set anywhere from 1% to 100% of full brightness, while others cannot go below a 20% threshold.

Find more tips and insight to equip your facility here.

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The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.