In article et, David
Martel wrote:
Miami.

Lots of humidity in Miami so clean the fixture contacts with a bit of
sand paper. You seem to describe having a working fixture so test all of the
bulbs (or as many as will fit). Check to be sure you bought the right
fixtures. Test the ground and the ballasts.

Another thing that occaisionally works: Clean the tubes.
Sometimes they get a little film of dirst including salt from sweat of
people handling them, or from salty air in coastal areas. In high
humidity, this little film of salty dirt will become hygroscopic and
become conductive. That can screw up the electric field distribution
within a tube that is trying to start.

Also look for:

1) Proper grounding of fixtures and ballast cases and make
sure you have no hot-neutral reverses anywhere. That can also affect
electric field distribution within tubes that are trying to start and
sometimes interferes with them starting.

2) Tube/ballast mismatch. Those newer T8 (1 inch diameter) tubes will
often not work at all if the ballasts are for T12 (such as F40), and will
usually be overpowered and/or have unstable operation if they do. Also
there are different kinds of 1.5 inch diameter (T12) 4-footers. Most
but not all are F40 and should work on ballasts for F40 - check the
ballast labels to see if they are rated for F40 and that the tubes are
F40.

3) Some F40's are the "energy saver" or the like ones, which are 34 watt
ones. Because they have a different gas in them, they can be crankier and
more difficult to start than "true F40".

- Don Klipstein )