Prior to the LED lighting transformation, the most common light source in the commercial market was the linear fluorescent lamp. The original linear fluorescent lamp was the T12 which operates on a magnetic ballast. In the early 1990’s the T8 lamp was invented which operates off an electronic ballast. The T8 lamp is much more efficient and lasts longer than a T12, so a majority of the market upgraded to T8 fluorescent systems. One additional and often overlooked benefit of converting from T12 to T8 was the reduction of flicker.
T12 Magnetic Ballast Flicker
T8 Electronic Ballast Flicker
As you can see, the T8 electronic ballast system drastically reduced the flicker effect of linear fluorescent tubes, but T8 lamps are now being replaced by linear LED tubes at a rapid pace. Following the logic of T12 to T8, LED tubes reduce energy and last longer than T8 fluorescent bulbs. But is anyone taking the time to think about the quality of light they are getting from LED and specifically the flicker effect of LED?
With any light source there are varying levels of flicker, but there are so many LED options available that the flicker varies more than any other light source. The following graphics illustrate the flicker range of some LED products in the marketplace today:
What determines flicker in LED sources
It all comes down to the driver. If the LED product has a high quality driver, the flicker effect will be minimal. If the LED product has a low quality driver, it is much more likely to flicker.
Why do we care about flicker?
There are several reasons why flicker is an issue, but the primary reason is for the health of the people in the environment being lit. Flickering can cause migraines, delayed performance, eye strain and potentially seizures.
Going back to the title of this article, there are many LED tubes in the marketplace today that flicker similar or worse than T12’s on magnetic ballasts did. There are several types of LED tubes, but the Type B LED tube is by far the most popular LED tube. It is also the most susceptible to flicker. The Type B LED tube operates off direct line voltage, so the driver is built into the tube. That means the driver needs to be small so it’s difficult to put all the components needed to allow for minimal flicker. That said, there are now Flicker Free Type B LED Tubes available.
Flicker is not a major concern in all applications, but every facility with linear fluorescent will be converting to LED at some point so take the time to consider it. Here are some steps you can take to make sure you have the flicker effect under control:
- Test the LED in your application
- Buy a hand-held flicker meter
- Become familiar with flicker metrics
- Understand employee’s sensitivity to flicker and applications that require attention to flicker in your facility
Or you can save yourself some time and work with a lighting partner who understands the value of high quality lighting.