What to do if your T12 magnetic ballast goes bad (2024)

Posted by Francine Pitassi on

What to do if your T12 magnetic ballast goes bad (7)

This article has been updated with new information and new products. It was originally published in 2017.

If you still have T12s in your building and they run on magnetic ballasts, you may soon face a problem: what do you do when your ballasts die?

Well, like T12s themselves, magnetic ballasts are becoming harder and harder to find these days. They're really no longer in production in the U.S., so most people today are running T12 fluorescents on electronic ballasts.What is a ballast? Read more.

Before we get into troubleshooting options, let's briefly determine how to tell if a ballast is bad.

What to do if your T12 magnetic ballast goes bad (8)

5 symptoms of a bad fluorescent ballast

If your fluorescent lighting is displaying any of the signs below, it could be a symptom of a bad ballast:

Flickering

If your lighting is flickering or strobing periodically, it's not necessarily that the bulb, or tube, is about to burn out. It could just as well be that the ballast is going bad.

Buzzing

Bad ballasts often buzz, or hum, when they're on their way out. If you've been hearing this, you need to test the ballast.

Delayed start

If your fluorescent lighting starts to act like HID when you turn it on, and it's slow to reach full brightness (what lighting experts call illuminance), your ballast is most likely the culprit.

Low output

Dim light or low lumen output is almost always the cause of one of two things: an old fluorescent lamp or an aging, bad ballast.

Inconsistent lighting levels

Fluorescent lamps almost always experience color variation and fading. So, at different stages of the lamp's life, different light levels will be produced. But if you're seeing dark corners and inconsistent lighting in your space, it may not just be because of the lamps. It could very well be the ballast, too.

Read more:Here are your LED replacement options for T12 fluorescents

T12 magnetic ballast replacement options

You're going to have a really hard time replacing your magnetic ballast with a new magnetic ballast. But you've probably figured that out by now.

Here's what you can do:

1. Switch to an electronic ballast, keep lamp

This is probably the cheapest, least labor-intensive option, but not by much. Once you understand the total cost of lighting, though, you'll see that there's a better long-term solution. The "work smarter, not harder" approach to this debacle would be to swap out the lamp while you're swapping out the ballast, for a clean, full upgrade.

That said, you can run most T12s off an electronic ballast, so if you think your lamps still have a lot of life in them, this is an option.

2. Switch to an electronic ballast, switch to a T8 fluorescent

As mentioned above, if you're going to climb a ladder to do a ballast change out, you may as well carry a lamp up there with you. Since T12s have been mostly phased out of production, the most affordable option would be to stay with fluorescents, installing a smaller-diameter, more energy-efficient T8 lamp.

Before switching from T12 to T8, be sure to have a conversation with your lighting specialist about which sockets you need.

For more on this, check out our post, "Shunted vs. non-shunted sockets: How to tell what you need."

3. Switch to an electronic ballast, switch to T8 linear LED

Depending on your application, and the average burn time of your lamps, this is probably the best play for both long-term savings and upfront cost. The cost of linear LEDs has come way down and, all in all, there are very few applications where you'd be better off with fluorescents.

Here's an article to help you better weigh linear LED vs. linear fluorescent.

As a side note, there is now a product that is actually compatible with both magnetic and electronic ballasts. So if you're looking to upgrade T12 tubes to LED but you don't want to replace all of the ballasts at once, the Philips UniversalFit tubes may be an excellent option to consider.

4. Switch from T12 to a new integrated LED fixture or retrofit kit

If you have the capital to completely retrofityour lighting, one option to consider is going with a new LED fixture. This optionprovides great visual appeal while carrying some of the longest life ratings and highest efficiency options available in a lighting system.Here's a list of pros and cons for this option, from our article, 'LED lamp replacement vs. LED fixture: Which is best for you?':

LED fixture pros

  • Maximum control over light output and placement (great for situations where lighting design is paramount)
  • Longer life rating and efficacy than LED replacement lamps
  • Lower maximum fixture wattage than traditional fixtures, which is advantageous for meeting strict building codes or Title 24 standards
  • Excellent performance for controls and dimming

LED fixture cons

  • Longer, more expensive installation
  • Higher up-front cost than LED replacement lamps
  • Potential for difficulty in upgrading to future emerging technologies

We carry many of these products in our online store, and if you're a business customer you can sign up for an account to receive business pricing.

Or if you're looking for additional help in determining the best course of action, we would be happy to help. You can contact us here.

What to do if your T12 magnetic ballast goes bad (9)

What to do if your T12 magnetic ballast goes bad (2024)

FAQs

What to do if your T12 magnetic ballast goes bad? ›

If the ballast goes bad your lights are subject to overdriving or underdriving. This results in your bulbs appearing to be going out.

How do I know if my T12 ballast is bad? ›

2. Look for warning signs that the ballast is failing.
  1. Buzzing. If you hear a strange sound coming from your bulbs or light fixture, like a buzzing or humming noise, that's often a sign your ballast is going. ...
  2. Dimming or flickering. ...
  3. No lights at all. ...
  4. Changing colors. ...
  5. Swollen casing. ...
  6. Burn marks. ...
  7. Water damage. ...
  8. Leaking oil.
Jun 25, 2020

What happens when a ballast goes bad? ›

If the ballast goes bad your lights are subject to overdriving or underdriving. This results in your bulbs appearing to be going out.

How do you tell if a ballast is blown? ›

When a ballast starts failing, it will typically buzz or causes the bulbs to flicker. These issues can sometimes happen while it is operating as expected, so it's important to check the equipment before assuming a replacement is necessary.

What is the life expectancy of a magnetic ballast? ›

Benefits of Magnetic Ballast

Low price with long lasting life up to 20 years, when comparing to electronic type with 5 years life.

How do I know if my ballast needs to be replaced? ›

Signs of a Bad Ballast
  1. Low output. If the lights remain dim for several minutes after you've turned them on, you could have an issue with your ballast, especially if you've just replaced your bulb.
  2. Flickering. ...
  3. Buzzing. ...
  4. Inconsistent lighting levels. ...
  5. Delayed start.
Nov 20, 2020

Do magnetic ballasts wear out? ›

As discussed earlier, most ballasts can last up to 30 years. This means that if your building was constructed a few decades ago, it's likely that the old magnetic ballasts with their internally-used oil are still in use. The oil helps to cool the ballast components and preserve its efficiency.

Is it worth replacing a ballast? ›

The good news is that a typical ballast will generally last about 20 years, so you won't have to worry about replacing them very often. However, cold environments and bad bulbs can factor into the mix, causing the lifespan of the ballast to decrease significantly.

What is the number one reason ballast fail? ›

If it is a two-bulb or four-bulb fixture, replace the pairing of tubes. Flickering fluorescent tubes can cause the ballast to overheat and fail prematurely! Causes of Ballast Failure: Premature ballast failure is usually caused by the surrounding environment. Heat and moisture are enemies #1 and #2 to your ballast.

How to tell if magnetic or electronic ballast? ›

Simply turn the light on, then take a photo of the fixture using your smartphone or digital camera. If there are no dark bands on the resulting image, you have an electronic ballast that is likely to work with direct drop-in LED tubes (with caveats: see the next section below).

Can a bad ballast start a fire? ›

Overheated fluorescent lights can cause fires! Overheating of the ballast could result in the following: Ignition of nearby combustible materials. Explosion of the ballast due to the generation of gases inside.

What does a magnetic ballast do? ›

Magnetic ballasts are sometimes called chokes because they are effectively set up to limit the current flowing around the lighting circuit. They do this by harnessing the electromagnetic field that is generated when current flows through a tightly wound coil.

How long does T12 ballast last? ›

According to the Certified Ballast Manufacturers Association, the average magnetic ballast lasts about 75,000 hours, or 12 to 15 years with normal use. The optimum economic life of a fluorescent lighting system with magnetic ballasts is usually about 15 years.

Are magnetic ballasts being discontinued? ›

These standards are now applied to magnetic ballasts used to light various fluorescent lamps, effectively causing the phase-out of these ballasts in 2010. Many manufacturers have already ceased production of magnetic ballasts in anticipation of the phase-out.

Can I replace a magnetic ballast with an electronic one? ›

One such recurring inquiry is whether a magnetic ballast can be replaced with an electronic ballast. We recognize this is a vital question for those considering upgrades or replacements of their lighting systems. Yes, a magnetic ballast can indeed be replaced with an electronic ballast.

How do I know if I need a new headlight ballast? ›

Signs of Ballast Failure

There is a good chance that your ballast is the cause of your lighting problems if your headlights are dim, changing colors, buzzing, or flicker. When inspecting it for potential issues, any burn marks, leaking oils, or swollen casing are indicators of failure.

What causes a ballast to burn out? ›

Every ballast has an ambient operating temperature range and UL location rating. When it's too hot or too cold, the ballast can burn or fail to start your lamps at all. Heat combined with prolonged condensation inside an electronic ballast can cause corrosion and ballast failure.

How do I match a replacement ballast? ›

How to pick a fluorescent ballast
  1. Step 1: Consider the lamps you're powering. ...
  2. Step 2: Consider how many lamps you're powering. ...
  3. Step 3: Consider what start type you need. ...
  4. Step 4: Consider the voltage powering your fixture. ...
  5. Step 5: Consider the dimensions of your ballast. ...
  6. Step 6: Consider the light output.
Sep 14, 2022

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