This article was updated on 10/24/17 to clarify that direct connect LEDs -- or LEDs that connect directly to ballasts -- do have drivers inside them, and these drivers are designed to work with the ballasts.
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As businesses continue upgrading from fluorescent lighting to LED lighting, one question sits at the crux of the upgrade: should you retrofit the lamps using existing ballasts, or remove the ballasts and direct wire the LEDs?
Here's what we mean:
As we discussed in our article, Replacing T8 Fluorescent Tubes with T8 LED Tubes, LEDs need something to safely modulate the energy running through them just as fluorescent tubes do. Fluorescent tubes use ballasts -- external to the lamp -- for this purpose and LEDs originally used something called drivers -- also external to the lamp -- which effectively do the same thing. (Many LED lamps still use external drivers.)
So originally to upgrade from fluorescent tubes, you would remove the old lamps and their ballasts; direct wire drivers instead of ballasts; and then connect the LED tubes to these external drivers. In the interest of making things simpler, manufacturers developed LEDs that could work directly off the ballasts that were already being used. No external drivers needed. (There is a driver inside the LED that works with the ballast; this must be an electronic ballast, and you still have to make sure LED and ballast specs are compatible.) Philips, for instance, came up with their InstantFit line of LEDs.
Many new LED tubes, however, come with integrated drivers, or drivers that are built in (much like the LED bulbs commonly used in homes) for direct wire purposes. These allow you to entirely remove old lamps and ballasts and connect the new LED lamp directly to the power source without a separate (external) driver.
In both instances, there are drivers inside the LED, one designed to work with electronic ballasts and one designed to work directly with the power source. [Article continues after image ...]