"kev" wrote in message
...

I opened up the ballast box to see what type of ballast is used.
It's a Philips e-Matchbox, e-M124SH ballast. It's difficult
to find specs on that ballast, but it is labelled as

1 x TLD 15/18
1 x PLL 18/24, 1 x TL5C 22
1 x TL5 24 HO


The ballast is capable of driving a 24W tube - 25W is not really going to
be a problem. The only possible problem I can see is the extra heat
generated by both the tube and ballast. If the 25W tube fits, I'd
monitor the heat produced.

Hmmm... From what I can figure out by doing web searches, a PLL
tube is a compact fluorescent, and a TLD tube is a T8 tube. So, if
they ballast can drive a 24W compact fluorescent, can it also drive
a 25W T8? Looking at the labelling, I guess the answer is no. On the
other hand, the G25T8 is rather unusual -- it has the same physical
dimensions as the G15T8, yet produces 10W extra.

I always thought that the wattage of a fluorescent tube dependent
purely on its lenght (for a given diameter) but, apparently, that's not
the case for the G15T8/G25T8.

Sigh... I wish there were a place on the web where I can just look
things like that up, but I can't find one :-(

Michi.

--
Michi Henning Ph: +61 4 1118-2700
ZeroC, Inc. http://www.zeroc.com