There are 3 basic types of LED bulbs, and a 4th that is a combination.
1 is a retro bulb that will work with the existing ballast, which I think is a waste of electricity because the ballast is using electricity.
2 is a bulb that will receive 120 V directly from one end, and three, a bulb that receives half of the 120 at one end of the bulb and half of the electricity at the other end of the bulb.
3 is a combination bulb that can be wired any of the 3 ways.
This describes a shunted, or double-ended bulb, rewire; a non-shunted conversion is similar, but slightly different.
Non-shunted vs. shunted socket differences are due to how electric current flows through the light fixture. Current will flow in a shunted socket by a single path, but through multiple paths in a non-shunted socket. The bulb could burn out quicker, or short if the wrong one is used.
Shunted sockets of fluorescent lights are for instant start ballasts, while non-shunted work with others like trigger start or pre-heat. The ballast gives enough voltage to start the bulbs then regulates the current.
A voltage meter set to continuity would confirm whether the lamp had a shunted or non-shunted socket – a non-shunted would show no continuity. Direct wire is the most energy efficient because it doesn’t require a power source controller, like a ballast, to operate.
Confirm you have a shunted fixture. Otherwise, replace the non-shunted lamp holders (called tombstones) or wire for a shunted fixture. Using non-shunted tombstones can short the sockets and damage the LEDs.
The best is to disconnect the ballast and wire directly to the bulb.
When converting a broken electronic fixture that uses fluorescent tubes into a LED fixture follow these basic steps: 1. Disassemble the end of the fixture where the power cord goes in and see if you can locate the electronic ballast and remove it but don’t cut the wires until you have to.
2. Know where the wires come off of the electronic ballast and go to the tomb stone connectors that the bulb attaches to and see if you can use ‘end feed’ LED tubes or if you can use ‘shunted’ LED tubes. It’s important to know that you have a choice because one maybe more expensive than the other and if you can wire your fixture either way pick the way that’s most economical.
3. Connect the power cord wires to the respective wires to feed the LED tube, you must use the diagram that comes with the tubes, and you can either wire in or bypass the switch if the fixture has one.