LED light tubes are popular replacements for the long, fluorescent light tubes, as they can last much longer and don't contain toxic mercury. Most of these tubes are designed to simply fit into the fluorescent light fixtures you already have; you can just remove the fluorescents, install the LEDs and you're done. Some LEDs, however, will work better if you remove the ballasts within the light fixtures that work with the fluorescents. This requires a slight bit of electrical work to replace the bulbs.
Consult with the vendor that you get the LED tubes if you need to remove the ballasts in your light fixtures. Some LEDs can still work with the ballasts of fluorescent fixtures, but might still might cause problems with the amount of power consumed.
Make sure the light switch has been off for at least 30 minutes to an hour. Detach and remove the acrylic (or other type material) shielding covering the fluorescent bulbs if you use such a cover.
Disconnect the bulbs and store them away safely. Do not throw them away or place them somewhere that they might break.
Open the panels to the ballasts on the light fixture. Twist the metal tabs on the edges of each panel to remove them.
Locate the ballast and disconnect it from the wires at both ends by removing the wire nuts or cutting the wires. Pay attention to how the wires are lined up before you cut them.
Connect the wires on both sides together by stripping an inch off the insulation, twisting the bare wire together and wrapping it in electrical tape. You must connect each wire to the one that was directly opposite it on the other side of the ballast. If the red and black wires looked like they were connected through the ballast, connect them now.
Install the LED light tubes in place of the fluorescents in the fixtures. Close up the ballast panels and replace the acrylic cover. Turn the lights on to test them.