Updated 1/14/25 by Angela Rogers
Unless you're an electrician, you've probably never changed a ballast. Chances are, when your garage fixture or kitchen light went out, you changed the bulbs, and when that didn't work, you went to an overpriced hardware store and bought a brand-new fixture. Sound familiar? Unfortunately, you could've saved a lot of money by switching out the ballast—an investment of only $10 to $15.
But with so many options out there, how would you know which ballast to pick? The truth is, it's pretty simple. There are tons of fluorescent ballasts to choose from (we have nearly 300 on our site!), but most business owners and even homeowners will find it easy to wade through that seemingly never-ending selection if they concentrate on just 3 key specs: Bulb type, start method, and ballast factor.
Why Fluorescent Light Ballast Matter
Ballasts are the cornerstone of any fluorescent light fixture. Without them, your fixture wouldn’t operate. A ballast is a device that regulates the current and voltage going to the lamps. The current and voltage are spiked rapidly to start the lamp, then they are limited to keep the lamp producing a steady light. Without this regulation, the tubes would burn out in seconds due to the uncontrolled current draw.
Selecting the Right Fluorescent Bulb for Your Ballast
Needless to say, this is the most important part. If you don't know what type of fluorescent bulb you're using, you're going to have a hard time figuring out which type of fluorescent ballast to buy. Fortunately, most fluorescent fixtures will use one of three common bulb types: An F40T12 (4' long; 1.5" in diameter), an F32T8 (4' long; 1" in diameter) or an F54T5 (46" long; 0.625" in diameter). If your bulbs don't meet one of these descriptions, you'll need to check the etching near one of the ends of the fluorescent bulb (a good idea even if you think you know the bulb type).
| Bulb Type | Ballast Type | Common Applications |
|---|---|---|
| T8 | Electronic Ballasts | Office Lighting |
| T12 | Magnetic Ballasts | Industrial Setups |
| Compact Fluorescent | Dedicated CFL Ballasts | Residential |
Choosing the Best Start Method for Fluorescent Light Ballasts
Once you've determined what type of fluorescent bulbs you have, don't burn them out prematurely by choosing a ballast with the wrong starting method. As discussed in a previous article on how to extend the life of a light bulb, an instant start ballast hits the fluorescent bulb cathodes with about 600 volts every time you flip the light switch. As you might imagine, the bulb can only stand so many of those on/off switches. Consider where your fixture is installed. Offices, boardrooms, and retail spaces tend to stay lit for long periods, so use an instant start ballast should be fine, as long as you don't switch the lights off and on more than about 3-4 times a day. Hallways, stairwells, and bathrooms are switched much more frequently, especially since the lighting in these areas is often controlled by an occupancy sensor. In these areas, it's best to use a programmed start ballast, which will heat the bulb cathodes more slowly and prolong its life.
Understanding Ballast Factor in Fluorescent Light Ballasts
Finally, you need to consider light output. "What?" you say. "You mean the bulb isn't exactly the brightness it says it is on the label?" Nope. The light output shown on a fluorescent bulb's label, expressed in lumens, is figured using a normal light output ballast with a ballast factor between 0.77 and 1.1. A normal ballast factor is usually the right option, for "normal" circumstances. But if you don't need your room quite as bright, you can save electricity by using a a low output fluorescent ballast with a ballast factor below 0.77. On the other hand, if you are lighting a warehouse or manufacturing facility where brightness is important, you will need a high output fluorescent ballast with a ballast factor above 1.1, which will push the bulb to be 10% or more brighter than stated on the label.
Common Problems with Fluorescent Ballasts
Despite finding the perfect ballast for your fixture, it’s not uncommon to run into problems. Some the most common issues with ballasts are flickering, buzzing, and humming. In many cases, audible noise and flickering occur as part of normal operation. You might notice the lights flicker briefly went first turning the fixture on, and all ballasts emit some low noise. It’s when these become far more noticeable that there could be a problem. Excessive noise and constant flickering are all indicators of a failing ballast.
Ballasts can also cause electromagnetic interference (EMI) with other nearby devices. EMI is unwanted disturbances or electrical noise that disrupts the normal function of devices caused by electromagnetic fields generated by other sources. If your ballast is creating interference with other electronics, there are several ways to mitigate EMI, such as grounding, shortening wire leads, filters, and shielding.
How to Extend the Life of Fluorescent Ballasts
With proper care and maintenance, ballasts can last for many years. This helps lower maintenance costs over time and reduces the number of replacements over the life of the fixture. Here are some tips for extending the life of your fluorescent ballast:
Choose ballasts that are rated for the ambient temperature of area the fixture is installed in.
Look for reputable brands that are known for longevity and quality.
Make sure that the new ballast has the correct wattage to match the tubes.
Ensure the fixture is designed for proper ventilation and heat dissipation.
Clean your fixture regularly. Able be sure to check the ballast and wiring for any damage.
Reduce power consumption by pairing dimmable ballasts with dimmers.
Avoid frequent on/off cycles. For these areas, consider pairing your fixture with sensors.
Of course, if you need something more specialized like a sign ballast, dimming ballast, or circline ballast, you'll likely need an equally specialized electrician. The same principles still hold true, however, so if you need to call an electrician, at least he'll be impressed by how much you know! Find the perfect fluorescent light ballast for your fixture by visiting 1000Bubls.com or call 1-800-624-4488 to speak with one of our lighting experts.
