Homeowner Forum / Repair / January 2010

Try pulling / pushing the wires going into each bulb socket. These can be
loose.

"Charlie"  wrote in message

 Did you check the type of bulbs specified by the ballast label to be
sure you are using compatible bulbs?

 For example, there are a few different 4-footers that have 2 pins on
each end:

1:  25 watt cheap shop light ones 1.5 inches in diameter.  These lamps
should only be operated on ballasts rated for these lamps.  Ballasts that
rated for these lamps may be rated for no other 4-footers, and/or may be
OK with 32 watt 1 inch diameter 4-footers, and/or may safely operate (at
reduced power) "true 40 watt" F40 4-footers.

 Use of 34 watt "energy saving F40" in a 25 watt fixture has significant
chance of cranky operation, including flickering and/or snaking/swirling
and/or beading/banding, especially in cooler temperatures.

 Use of "true 40 watt" F40 / F40T12 is not as bad as use of the 34 watt
one, but it may get cranky as above, especially in cooler temperatures.

2:  1 inch diameter F32T8 32 watt modern "newfangled" 4-footers.  They
should only be used with ballasts rated for them (in fixtures having
ballasts rated for them).  Ballasts rated for these are usually not rated
to run any other 4-footers, although a few may be rated to run 25 watt T12
(1.5 inch diameter) 4-footers.  Most ballasts for these will usually run
European 36 watt 1 inch diameter 4-footers OK or reasonably OK, but this
is not guaranteed.
 Most ballasts rated for 32 watt 4-footers and shorter length lower
wattage T8 (1 inch diameter) lamps/bulbs will run the 25 watt T12 4-footer
at least fairly OK and will often run "true 40 watt" F40 "fairly OK", at
least in warmer temperatures.  (WARNING - if the ballast is not actually
rated to operate these, then officially you are abusing the ballast by
using it with such lamps/bulbs.)  Use of F32T8 ballasts with 34 watt T12
will underpower those to extent of fair chance of "cranky" operation,
including beading/banding, flickering, and/or snaking/swirling, especially
in cooler temperatures.

3:  European 36 watt 1 inch diameter.  Ballasts for those usually take 230
volts and are often compatible with 240 volts.  Ballasts for these tend to
do at least fairly well with North American 32 watt T8 (1 inch diameter)
4-foot lamps/bulbs and have fair chance of doing fairly weill with 4 foot
25 watt T12 (1.5 inch diameter), and with "true 40 watt" F40T12 although
underpowering those somewhat.  Ballasts for European 36 watt 1-inch-diameter
4-footers have slightly better prospect with 34 watt 1.5 inch diameter
bulbs than North American ballasts for the 32 watt ones - but that is not
saying a much good news in that area of running 34 watt T12.

4:  34 watt "energy saver" version of F40T12:

 Those have some tendency to be cranky, especially in cooler
temperatures.  These also need to be used in fixtures (or run by ballasts)
specifically rated for these 34 watt lamps/bulbs.

 These bulbs tend to work OK in fixtures (or run by ballasts) rated for
"true 40 watt" F40 / F40T12.  If the ballast is rated for 40 and not 34
watt, then the ballast's life may be shortened by using it with the 34
watt "energy saver F40 / F40T12".

 Ballasts that are rated for both 40 watt 4-foot F40 and 30 watt 3-foot
F30T12 (1.5 inch diameter), especially if of "rapid start type", tend to
be OK with 34 watt 4-foot bulbs/lamps.

 One common ballast failure of dual-F40 rapid start ballasts that is more
common with 34 watt bulbs has main symptom that the ballast "eats bulbs",
2nd-place-most-noted symptom is line current being something like 1.5-1.7
amps rather than around .8 amp.  3rd place is the bulbs running only
slightly abnormally bright and/or flickery and/or off-color and/or at
slightly higher temperature than normal.

5:  A much less common one - the 35 watt "energy saver F40 / F40T12".
This one is significantly less "cranky" than the 34 watt version is, due
to having gas composition more like that of "true F40" than is used in the
34 watt version.  It usually works A-OK with any ballast and in any
fixture rated for the "true 40 watt version".  As for
being-hard-on-the-ballast - the 35 watt version of F40T12 bulb is OK to
use with ballasts rated for use with both 40 and 34 watt versions, and is
OK with ballasts rated for both 40 watt 4-foot and 30 watt 3-foot 1.5 inch
diameter versions, as long as starting method compatibility is maintained.

=============================================

 Other than bulb/ballast compatibility issues, I would worry about
non-ideal temperature, beaten-up starters if you are using starters, and
any use of those 34 watt "energy saving F40 / F40T12" bulbs that get
cranky easily.

 Another common problem area - "trigger start", which is a variant of
"rapid start" having increased compatibility with "preheat bulbs".  My
experience is increased crankiness, especially with the dual-20-watt
2-footer ...

 (My experience suggests that 20 watt F20T12 2-foot F20T12 tends to be
fed more like 17 rather than 20 watts anyway...)

 If you have a dual-20-watt / dual-F20T12 fixture taking 2-foot 1.5 inch
diameter bulbs, I would replace the ballast (or entire fixture) to use
the 17 watt F17T8 (1 inch diameter 2-footer) instead.

- Don Klipstein (don@misty.com)

   Are you sure you have a good solid ground?

Since you have two identical fixtures...have you checked the wiring
(compared color for color) just in case there is a difference.
I recently had 4-tube, 4-foot, electronic ballast where 3 tubes were
out and one dim. Turned-out...the only bad one was the dim one!
It wasn't dark at the ends but it was loading-down the voltage. (These
were all new tubes when the ballast was changed-about 2 months ago).

bob