ballast with wrong lamps - Electrician Talk - Professional Electrical Contractors Forum

JohnJ0906 · 08-05-2007, 07:47 AM

Yes, I know I should check the label 1st!

I have a 4-tube, 2 ballast T-8 fixture. When I changed the lamps, I replaced them with what was installed (T-12) without checking the label. It was just a few months ago, and when they burned out again so fast, I went to check it, and saw the label "T-8 lamps only"

It's what I get for trusting the person before me, I know.

The question is, would this damage the ballasts? Should I replace them up front, or just re-lamp properly, and see what happens?

MDShunk · 08-05-2007, 10:01 AM

Of all the T8 ballasts that I've run across that have had T12's in them, the lamps are normally fine and the ballast is toast. For that reason, when I convert a fixture (which is what I normally do as T12 ballasts fail), I write on the ballast cover "T8 lamps only", and I warn the owner. In my experience, installing T12 lamps in a T8 fixture almost guarantees that the ballast will die. Your results may vary, but those are mine.