DIYbanter - View Single Post - Replace old fluorescent tube with brighter?

Don Klipstein

In article .com,
wrote:
Victor Roberts wrote:
On Thu, 30 Nov 2006 13:53:04 GMT, Alex
wrote:

My understanding of that other post was that older
electronic ballasts had some reliability problems and that
make him shy away from even the modern, more reliable ones.

indeed, but that does not imply that the new fitting will be more
reilable or as reilable as the old. On the whole it tends to be the
other way round. One only need think bathtub curve to see that. Then
theres the 2nd factor of a more price-aggressive market today. So its
no surprise new goods dont have anything like the life expectancy of
older kit.

Electronic components are getting less expensive and sturdier, more
robust. Circuit designs are improved upon those that failed the test of
time.

Bigger iron core items of older technology have not enjoyed as much
reduction in production cost.

As opposed to meow2222/NT I believe that we should try to
save energy whenever possible. Your one lamp fixture may
not save a lot of energy, but when multiplied by the number
of people making this decision, the impact can be large.

Maybe then you could explain to us how travelling out to get a new
fitting and putting it up will save more energy than the 7w the older
fitting would consume with a T12 tube. Or even more to the point, the
smaller amount of energy difference involved in using a T8 in an older
fitting.

Modern USA 2-tube fixture with electronic ballast and two F32T8 lamps
often has the lamps receiving guesstimate 29 watts each (most fluorescent
lamps at a given current have both a slight decrease in power consumption
when frequency gets to a few KHz or more and a very slight increase in
light output when the frequency gets into the dozens of KHz), so the
fixture consumes fairly close to 64 watts.

The USA-traditional dual-F40 fixture had the lamps receiving 40 watts
each plus ballast loss that I guesstimate to be not much under 10 watts -
for power consumption in the upper 80's of watts, approaching 90 watts.

So I believe that replacing F40T12 lamps with F32T8 ones and replacing
the traditional dual-F40 ballast with an electronic one for two F32T8
lamps will reduce power consumption by somewhere around 24-25 watts.

Also, all popular F32T8 lamps made for "general lighting purpose" are
triphosphor. These do not dull/darken most red objects and green objects
the way most non-triphosphor fluorescents do. Non-triphosphor includes
even most fluorescents with color rendering index around 90-92 although
that range dulls/darkens reds/greens less than "old tech cool white and
warm white".

Plus, I expect that when you see the cost of a triphosphor
version of your current lamp that alone will start you
looking at T8 systems.

The OP has a T8 compatible system already. The OP is not in America.

1. I am speaking from and for America, the land of opportunity, including
a megatonnage of fluorescent fixtures having significant room for
improvement.

2. In a fixture having a magnetic 2-lamp rapid start ballast for two
T8 lamps, replacement of the ballast with an electronic one will
probably save more than 7 watts, since not only is the ballast loss
reduced but also the lamps can be fed a little less power. This even goes
to extent of giving the lamps only 29 or 28 or so watts each - slight
shortfall in initial lumens is partially balanced out by improvement in
lumen maintenance. Also, many lamps at same current consume 1-2 watts
less at high frequency (a few KHz or more) than at low frequency due
to reduction of a frequency-sensitive "anode fall" loss that most
fluorescent lamps have.
If the ballast output frequency is high enough for the "imprisonment
duration" of a 253.7 nm photon to get above or even into the ballpark of a
1/2-cycle of the ballast output frequency, then the RMS "electron
temperature"/"free electron kinetic energy" should be a couple/few
hundredths of an eV less than if the lamp received low frequency AC and
that can reduce the ratio of 184.9/253.7 nm radiation to an extent
sufficient to have a slightly significant impact on phosphor
deterioration.
Lamps alone can have power reduction about 7 watts per pair by replacing
a non-electronmic ballast with an electronic one, even without change of
lamps. Ballast loss redution is an additional couple to a few watts.
Savings get much bigger (typically over 20 watts per 2-"bulbs") in the
many opportunities in "The Land of Opportunity" where such a change also
includes replacing F40T12 lamps with F32T8 ones. The nominal "per bulb"
wattage is decreased by 8 watts as in 16 watts per pair, in addition to
the roughly 7-watt-per-pair underpowering that modern electronic ballasts
fairly easily afford and in addition to saving a couple to a few watts in
ballast losses from use of better higher efficiency electronic ballasts.
That sounds to me like power consumption decrease of roughly 25 watts
per pair of 4-footers from replacing T12 lamps and the iron-core ballasts
for those with T8 lamps and an electronic ballast for T8 lamps.

- Don Klipstein )