Buyers of LED fluorescent replacement tube lights often ask if they can use a T8 sized LED tube in a T12 fixture. We cover most of the basics on how to choose LED tube lights for your application here but customers are often confused after purchasing when they receive an LED that is marked as T8.
As we describe in our how to article, T8 and T12 feature the same G13 bi-pin connector. T8 tubes are simply 1 inch in diameter versus the 1.5 inch diameter of T12 tubes. In an effort to make LED tube lights compatible with the internal dimensions of most fixtures, you will find that most LED tube lights feature a T8 or 1 inch diameter. They can indeed be used in T12 fixtures. With this said, T12 fluorescents for the most part use magnetic ballasts therefore, the only way to use LED tube lights with this type of fixture is to either purchase an LED ballast bypass tube light and bypass the ballast wiring or purchase a universal magnetic ballast compatible tube light.
Please note the above information is primarily directed towards 4 Foot bi-pin G13 T8 and T12 products.