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 drivers needed. (This works with electronic ballasts only, 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). These allow you to entirely remove old lamps and ballasts and direct wire the new LED lamp without a separate (external) driver. It sounds like a winning situation because you never have to think about replacing ballasts again.
But actually you do. It's just that now we're calling them drivers. And having them inside the lamp might not be ideal. [Article continues after images ...]
Ballasts generally last for many years, but they eventually die and have to be replaced. So it seems reasonable to want to eliminate them from the equation. But drivers also die. Since this is a relatively new technology, we don't know how long they will typically last, though quality drivers should also last for years. But eventually they go bad. And while the light-producing diodes of an LED lamp may last 50,000 hours and beyond, there's no telling if the driver itself will last that long. If it doesn't, and if that driver is built into the lamp, there's no way to just replace the driver. You have to replace the entire lamp.
So if you do choose direct wire LEDs, just remember that you're depending on the driver to last. Since the driver inside the lamp is new when installed, it may well last a good deal longer than the used ballast you have in place. But when that lamp dies for whatever reason -- even if it's just the driver -- you'll need to replace the entire lamp. This can be more costly than just replacing a ballast.
This doesn't mean direct wire is wrong, as this depends on your business needs. Maybe you prefer having a simpler system with fewer components, which is the benefit of direct wire LED tubes. And of course it's possible that drivers will long outlive ballasts. We'll have to see in the coming years. (And we expect established brands that have to stand behind their warranties -- the kind of brands we carry -- will provide better odds of longevity.) But it's worth knowing the pros and cons of direct wire versus a LED / ballast retrofit when making your lighting decision.