Lighting puzzle


I have a 4' Florescent fixture with 2 F40cw tubes. The tubes look like there half lit, sometimes they will fully light & other times there very low. I don't know if it is the fixture or tubes that are bad. I took 2 tubes out of another fixture that works properly & put them in the Fixture in question & they also lit very low. So next i put the questonable Tubes in the good fixture & they also lit very low in the good fixture. So i am back to the question which are bad or if the Tubes & fixture are both bad.
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desgnr wrote:

Possibly neither. This often happens when the ground connection is bad.
What's the ground connection got to do with it? A grounded reflector increases the capacitance of the discharge path in the tube to help in getting the conductance started. Or something like that. It's similar to the ground effect in aviation, only different.
By the way, it's only nine months until the government-ordered demise of magnetic ballasts.
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Hey! What's that about a governement mandated discontinuance of magnetic ballasts? What jurisdiction are we talking about? Federal, state, provincial???? Which country? Australia, Canada, UK, USA etc? I'm in Canada, not in the industry and with enough spare (old style) ballasts; and also a couple of electronic ones, for the string in my workshop) to last out my lifetime. But definitely interested in what's happening. (Like the Australian mandate of the use CFLs!). More, please? Regards terry.
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On Mon, 21 Sep 2009 08:40:52 -0700 (PDT), stan
...

http://www.aboutlightingcontrols.org/education/papers/ballast_law.shtml
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is it possible that some of the keystones in the questionable fixture have loose connections, thus causing arcing and corrosion on the tube pins? So that when you put the tubes in the good fixture they are still not making good contact?
nate
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It could be that the bulbs in the fixture were damaged by a bad transformer, which would also make sense that bulbs from another fixture don't work either. My suggestion: If the fixture is in poor condition, replace it. If the fixture is in good condition and you are electrically handy, get a new electronic ballast transformer for 2-32 watt T-8 lamps. You'll need the new lamps as well. This transformer will work much better than the magnetic one currently in the fixture and the lamps will give more light than the old 34 watt T-12 lamps. The transformer does not wire the same as the one in the fixture now, but it's actually much simpler to connect.

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