You will see either T8 or T12 stamped on one side near the end with the prongs. You also will see the lamp’s rated wattage, usually 32 watts for T8 and 40 watts for T12. Measure the diameter of the lamp. T12 lamps are larger than T8 lamps, with a 1 ½-inch diameter.

How do I know if I have a T8 or T12 ballast?

If no markings are available, the size in diameter of the tube is the easiest way to determine the type you have installed. T8 tubes are 1-inch in diameter and T12 tubes are 1 1/2 -inch.

How do I know what type of ballast I have?





You can determine whether you have a compatible fixture in seconds. 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 will work with direct drop-in LED tubes.

Do T8 and T12 use the same ballast?

T8 LED lamps which are not direct-wire compatible (with ballast) will require a T8 ballast to operate, so unless the T12 ballast in the T12 fixture is replaced with a T8 ballast, a non-direct-wire compatible T8 LED lamp will not work in a T12 fixture.

How do I know what kind of fluorescent ballast I have?

Method One – Use your smart phone camera. Stand under the light or a place close to the light and point your cell phone camera at the light. If you can see some strong dark strips flickering in your camera, it must be a magnetic ballast based light. Otherwise it should be an electronic ballast based light.

How do I identify a T8 bulb?

Linear fluorescent lamps typically include a “T” in the shape abbreviation with a number following it. This “T” stands for tube and the number that follows is the diameter of the tube. That number is divided into 8 to translate into inches. So a T8 has a one inch diameter.

How do I know if my bulb is a T8?





If you do not see markings, the size or diameter of the tube will be the easiest way to tell the kind that you have installed. T8 tubes will be one inch in diam. and T12 will be 1 1/2 inch in diameter. If you happen to have a tube that is relatively small in diameter, about 5/8 of an inch, it is a T5.

How do you read a ballast number?

The T stands for tubular and the number provides the diameter in 1/8 of an inch. Lamp diameter is determined by ballast type. Therefore, a T12 ballast must use a T12 bulb. A T5 ballast must use a T5 bulb and so forth.

How do you know if it’s the bulb or ballast?

One probe of the multimeter should touch the hot wire connections, while the other touches the neutral wire connections. If the ballast is good, an analog multimeter has a needle that will sweep to the right across the measuring scale. If the ballast is bad, then the needle won’t move.

How do I know what size ballast I need?

By selecting a ballast with an ideal ballast factor, you can optimize the light output of your fluorescent lighting system and maximize your energy savings. To estimate your total system lumens, multiply the rated lumens of your lamp by the ballast factor. For example, 3200 lumens x 0.77 BF = 2464 total system lumens.

What is a T8 electronic ballast?



The “T” in T8 indicates the bulb is Tubular, while the “8” means they are eight / eighths inch (or 1″) in diameter. 1/2 Lamps F32T8. 2/3 Lamps F32T8. 3/4 Lamps F32T8. F96T8 Ballasts.

Are all fluorescent ballasts the same?

Types of fluorescent ballasts

Fluorescent ballasts use three different types of starting technologies: rapid, instant, and programmed.

Do all fluorescent fixtures have ballasts?



All fluorescent bulbs require a ballast. All compact fluorescent (CFL) bulbs require a ballast, which is often integrated. All HID bulbs require a ballast, which is sometimes integrated. No LED bulbs require a ballast, although some are engineered to work with an existing ballast.

Do T8 bulbs need a ballast?

Most T8 LED bulbs do not need a ballast. The only type of LED tube that requires a ballast is plug-and-play. Used as direct replacements for fluorescent tubes, plug-and-play LED tube lights install without fixture rewiring, and operate off the existing fluorescent ballast.

Where is the ballast on a fluorescent light fixture?

Locate the wiring cover plate, usually in the center of the fixture. On either side of the cover, there will be tabs that catch in slots in the fixture. Squeeze the sides of the cover inward to slip the tabs out of the slots, and pull the cover down. This will expose the ballast and its wiring.

How do I know if my T8 ballast is bad?

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

  1. Flickering. …
  2. Buzzing. …
  3. Delayed start. …
  4. Low output. …
  5. Inconsistent lighting levels. …
  6. Switch to an electronic ballast, keep lamp. …
  7. Switch to an electronic ballast, switch to a T8 fluorescent.

What does a bad ballast smell like?



A common source of these odors is the fluorescent light ballast. When called to such an incident, you typically will find an electrical odor or a haze of smoke.

Why are my fluorescent lights flickering?

Flickering fluorescent lights can also be a result of temperature. If the air around the bulb is cold and circulating, the bulb won’t be able to generate enough heat to work properly. The internal temperature of a fluorescent bulb should be about 50 degrees Fahrenheit for it to work properly and optimally.

Are T12 bulbs being phased out?

In effect since July 2012, the legislation eliminates nearly all 4-foot T12 lamps, some 4-foot T8 lamps, most 8-foot T12 lamps, and almost all standard halogen PAR38, PAR30 and PAR20 lamps from the market. T12 technology is over 80 years old. Since that time, lamps and bulbs have been developed that just work better.

What happens if you put a T8 bulb in a T12 fixture?

The main difference between T8 and T12 tubes is the tube’s diameter. T12 tubes are 1.5″ in diameter while T8s are just one inch. All other things—socket sizes, lengths, distance between pins—are the same. T8 LED tubes won’t fall out if you try to install them in a T12 fixture—they’ll fit just fine.

Can I use T8 in place of T12?



T8 tubes are simply 1 inch in diameter versus the 1.5 inch diameter of T12 tubes. In an effort to make LED tube lights compatible with the internal dimensions of most fixtures, you will find that most LED tube lights feature a T8 or 1 inch diameter. They can indeed be used in T12 fixtures.