How to install a new T-8 Ballast in a flourescent light T-12 fixture

ejkia

How to install a new T-8 Ballast in a flourescent light T-12 fixture?

sdsester

They are expensive but you might want to think about just switching to the new LED tube arrays. Ballasts become irrelevant since they are no longer needed. No buzzing and we may both die before you have to replace the bulbs again.

jbfan

Follow the wiring diagram on the ballast.

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rjniles

You will also have to change the "tombstones". T12 tubes are 1.5 inches in diameter, T8 tubes are 1 inch. The pins on the T8's will not fit the old tombstones (white porcelain or plastic terminals that hold the end of the tubes). Unless this is an expensive fixture it is probably cheaper to buy a new fixture.

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nap

the pins are spaced identically so when changing from T12 to T8, you would not need to change the tombstones.

what you need to be aware of is if the tombstones are shunted or not and what your new ballast requires.

Jim Port

I agree with NAP. I have changed hundreds of t12s to t8s and never had a problem. The pins are the same spacing.

codeone

Correct, you will only have problems with the tombstones if you go to the newer T5 lamps.

frenchelectrican

The quickest way to tell if you have shunted tombstone is look at the ballast info if it say " Instat start " it will have shunted tombstone while " Rapid Start " useally not shunted unless specficed by ballast manufacter.

Some case you will see a marking " S " on the tombstone as well.

The reason why shunted tombstone due the T-8 filment can burn out early if only one side of tombstone is connected so the shunted is both pin on that end is shunted { tied together most case } it will make the bulb last longer.

Merci,Marc

spark plug

I agree. Most of the new/er ones (T8) are shunted.!

spark plug

I agree with both you and Nap! I also changed "Hundreds?" but a nice amount, and never encountered a problem on converting T12 to T8! But the wiring is different. (On the 2 light 96" . when converting from Magnetic to Electronic ballast)!

damons

I don't see the specifics, my T12 ballast has two yellow, black & white from left side, 2 red and 2 blue on right.

The T8 has one black, white & red on left, and 2 blue on right side of ballast, knowing this, the T8 has less wires, do I put the one red to the existing two red, and what do I do with the 2 yellow wires from lamps?

nap

as has been said several times; you follow the diagram on the ballast.

with yours, the black and white are for the incoming power; black to hot and white to neutral. the single blue would go to both tombstones on one end of the fixture and each red wire would go to only one tombstone on the opposite end of the fixture.

what I have done on fixtures that were a pain in the but to take apart, where there are two wires coming from the same tombstone, you simply connect those together and attach them to the one wire from the ballast that is needed at that tombstone. If you go clear to the terminals and remove the yellow blue or red wires, at any terminal where there was two wires, you would need to install a jumper between the two terminals of that particular tombstone to make it a "shunted" tombstone.

damons

Ok, I took a chance, the black and white where self explanatory. I took the two right blues and wires one side to the two reds of tombstones, the other blue to the two blues of tombstone, then wired two yellows from other side tombstone and attached to ballasts red wire, this should be right? I did turn on and lights work, hopefully were good.