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
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
Hey! What's that about a governement mandated discontinuance of
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!).
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?
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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