I was just wondering if LED tubes are used as retrofits in existing fluorescent fixtures are the ballasts, wether magnetic or electronic, are they still used for the LEDs or are they disconnected?

In most cases, LED tubes and LED retrofit lamps for HID lamps typically have the ballast bypassed which means that the LED tubes and LED retrofit lamps for HID bulbs are directly wired to the mains. In a few other cases, some LED tubes and some LED retrofit lamps for HID lamps use the existing ballast. However, the ballast bypass LED lamps are more efficient because the ballast losses are eliminated when the ballast is bypassed.

Eh, I've installed a number of the various types

- LED Tubes plug and play with existing T8 or T12 ballast
- LED tubes that must be direct wired to power feed
- LED tubes that require a LED specific driver (these are usually for dimming applications)

Have some LED bulbs in the flourescent lights at work-some of the LED retrofit bulbs are dying......Just the centers lighting-ends dark.Regular flourscent bulbs don't act that way.