A t12 ballast is a reference that essentially refers to the size of the tube of the florescent bulb that is being used. T12 tubes pull 40 watts, and are frequently being replaced with lower wattage t8 tubes, which operate on 32 watts.
When posing the question can a t8 light work on a t12 ballast, the short answer is no. Because the ballast is specific to the wattage of the bulb, and not necessarily the size, it doesn't matter that the tube is the same length, what matters is that a t12 ballast will push more power than a t8 light is designed to handle. The only way around the dilemma is to replace the ballast.
Cost of Replacement
Ballasts are not necessarily expensive; you can find a t8 ballast for under 20 dollars. Even if you have many that need replacement, this still does not amount to a huge expense. When you consider that the t8 is more efficient than the t12, the cost is easily justified.
Resources for Replacement
Ballasts can be purchased in your local hardware store. If you are in the market for something more industrial, there are a number of resources available online to purchase the right ballasts that you need.
T8 and T12 Light FAQ
Are T8 and T12 lights the same?
In many respects, T8 and T12 lights are highly similar. They are almost the same size, with T12 tubes being just a little bigger in diameter.
However, T8 lights produce more lumens than T12.
What is the difference between a T8 ballast and a T12 ballast?
The difference between T8 and T12 lights is in the size of the tubs. The T12 tubes are 1.5 inches in diameter and the T8 tubes are just one inch in diameter.
Other than this, there is no difference in the design, including in the ballast. Essentially, the ballast regulates the current in the light.
What is the difference between T8 and T12 light output?
T12 lights produce about 2,650 lumens. That's the amount of illuminating power they have.
By contrast, T8 lights put out around 2,800 lumens, which makes them brighter. These lights are not the same as T12 lights, but they are extremely similar.
Are T12 bulbs being discontinued?
A federal regulation from the U.S. Department of Energy in 2012 made T12 lights illegal to be imported or to be produced. These lights were not targeted specifically, but they no longer fell within new energy-efficient parameters set forth by the federal government.
Are T8 bulbs being discontinued?
While iridescent bulbs were targeted by environmental regulations, fluorescent and compact fluorescent lights have remained in production, including T8 lights. However, this is a continuously-evolving issue.
The UK passed regulations to phase out T8 lights by 2024. The law requires all business owners to get alternative lighting solutions and discard the outlawed bulbs as recyclables or as hazardous waste.
Similar legislation in the U.S. could also make the T8 illegal, as many support this change.