Can You Put T12 Bulbs in a T8 Fixture Without Shortening the Bulb’s Life?

Can You Put T12 Bulbs in a T8 Fixture

There is no contender for a Tubelight in the lighting industry. These fluorescent bulbs have evolved with time from changing to LEDs that are much more efficient these days.

One of the great things about a T bulb is that they last very long and can light up a large space. You don’t need a lot of bulbs to illuminate a 12 square feet room. One will do the trick. 

Although the T12 bulbs have been taken over by T8 bulbs, you might still have some T12s handy. So can you put T12 bulbs in a T8 fixture if you wanted? Let’s discuss the possibilities and outcomes in today’s article.

Can You Put T12 Bulbs in a T8 Fixture

While the T12 bulb and T8 can be identical in length, they are not in diameter. The T8 is a bit slimmer than the old T12 and runs better.

Most tube lights have a pin connector although you will find screws on connectors. But the base is G13, which makes you use a T12 in a T8 fixture.

Believe me, it will fit and work, but there are a few reasons that it might backfire. And that is not about the size of the bulb or the chemistry. 

Here are the things you should know before putting in a T12 bulb on a T8 fixture. 

Ballast Is the Main Thing

You might be thinking, both have the G13 connector, so why won’t it work? The T12 has a more complex connector with additional magnetic ballast sometimes. And that is where everything gets complicated.

The magnetic ballast is one of the things that consumes more electricity than modern-day ballasts that are already included in the connecting sockets. So if you want to put on a T12 in a T8 fixture, make sure to get the right ballast set.

Size Is Not an Issue

As we have told you earlier, the T12 and T8 are almost the same length. Both come in of a standard of 4 ft and can go up to 8 ft. The diameter of a T12 is a bit larger than a T8.

The thing they differ from each other is the way they work. While T12 needs a magnetic ballast, the T8 doesn’t need any additional ballasts. This is why you won’t find any ballast in a T8 fixture.

Go For the Alternative Ballast Kit for T12 Bulbs

If you are keen on fitting your T8 fixture with a T12 bulb, you have to put in a ballast kit. Which is easy to find in electronic stores and you just have to screw it in.

The wires are already set up from the factory and if not, it is easy to set it up yourself. You can ask a professional electrician for better fitting and safety if you don’t know how to do it. 

Do T8 Bulbs Fit In T12 Fixtures?

Yes, they do. But T8 bulbs don’t normally require a ballast and with the T12s ballast setup, it will drain the life out of your T8 bulb.

Normally a T8 bulb has 36,000 hours of lumens. If you connect it to a T12 ballast, it will go down to 2,000 hours. This is due to the high electrical voltage output from the ballast. This is why you should not put a T8 bulb in a T12 ballast setup.

The same thing goes for a T12 bulb in a T8 setup. It might not have a ballast setup that won’t regulate the electricity. And run down the lumen time of a T12s from 20,000 hours to 3000 hours.

Frequently Asked Questions

How long will T12 bulbs last with a T8 ballast?

Normally a T12 bulb has 20,000 lumen hours. If you fit it on a T8 ballast without the T12 setup, it will go down to 1500-3000 hours. It is best if you fit your T8 outlet with a T12 ballast before you put in a T12 bulb.

How do I convert a T12 fluorescent bulb to a T8?

To convert a T12 fluorescent bulb to a T8, you will need a T8 ballast kit. You will find it in any electrical equipment store. Then remove all the T12 ballast kit from your light fixture. A screw and a plier will do the trick. Then put in the T8 setup in the same place. And you are done. Remember to unplug and turn off the power before you even start doing the procedure. 


Getting a T12 bulb fitting in your T8 fixture is not big of a deal. You can find all the necessary equipment in the stores and with a little guidance and help from a professional, you can easily convert the whole system. The thing you can be proud of is reusing the fixture instead of buying the whole setup. Which is a kind gesture towards the environment and economy. 

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