10-19-2012, 09:21 AM
| || |
I thought that there was a difference in ballasts between T12 & T8. T12 typically uses magnetic ballast and T8 uses electrical ballast. Look at the ballast number and it will tell you what the ballast is rated such as QTP4X32T8/UNV sez this ballast is rated for a T8 lamp (UNV refers to voltage 120 or 220). The lamps are interchangeable in terms of fitting the socket yet using T8 lamp with a T12 ballast will cause lamps and ballast to fail prematurely.
One other aspect T8s are shunted, the T12s are not.
If the ballast connections are one wire to each tombstone (T8), then it must be shunted. If two wires to each tombstone (T12), then it cannot be shunted.
The reason being, the T8s are a 'cold cathode' design. High voltage and high frequency are used to start the arc inside the tube.
The T12s have a small heating element at both ends of the tube. Once it is hot enough, the arc will start at 60HZ.
The two types of ballasts are of different operating designs, hence the different connections and different lamps.
This is what I have learned about T12 & T8 lamps and maybe ole school by now with the fast changing technology.