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Re: T-8 Light and Ballast Questi


I agonized about this same topic earlier this year. 
If you are the kind of person that needs to solve this
to the n-th degree, you will be busy.  I posted my
after I did my research.  It might help.  

The short answer is that if you are looking for a
cost-effective, energy-efficient system that you can
put together inside a hood, it isn’t too tough to do. 
If you are looking for maximum light output
(overdriving bulbs) and costs-be-darned, you can still
do it rather easily, but need to do much more

The energy efficient solution is to call your local
electrical contractor supply house.  Don’t ask a
jillion questions, they will probably tell you that
they don’t sell to individuals – which isn’t the case,
they just don’t want to answer a jillion questions for
a $29 sale.  Ask the specific questions “I need a
electronic, instant start ballast for two (or your
number of tubes you want) T-8 fluorescent tubes that
are four feet long.  What is the make and model of
your generic ballast?  How much is it?”  Write this
info down and do your search on the internet for the
specs.  If the unit has a ballast factor of .88-.92
you are fine, buy it, and install it.  

For me this was easy because I was working with
refitting 4’ shop lights from t-12 to t-8.  If you are
not refitting an existing light, it gets more
difficult because you need to buy endcaps, a
reflector, and tube holders.  

The max light output solution doesn’t sacrifice a
whole lot of energy if you are working with standard
T-8 tubes.  From memory, I think you loose about 15%
energy efficiency when you overdrive your tubes.  Here
is where you look for the maximum ballast factor. 
Look for 1.18 and higher, again from memory.  This
ballast factor is usually obtained by using a ballast
designed for one more tube than you need.  Then you
cap the extra hot lead and your remaining tubes are

For either solution, AFAIK, the Macdonald’s Arch
Shaped Reflector is a myth for aquariums.  The
lighting contractors have said that they are available
from specialty companies for commercial fixtures that
go in 2 x 4 feet suspended ceilings, but they are for
two bulbs spaced evenly in a 2 foot opening.  BTW,
they ballparked the price at around $200 for a
fixture.  Useless…  Yes, you will benefit from a
reflector.  Ivo Busko wrote an informative post about
the reflectivity of certain reflectors.  I ran the
calculations using Ivo’s numbers to compare my white
painted shop lights to the polished aluminum
reflector.  The light increase wasn’t worth the money
spent to buy the Aqua Mirror in my case.  I did buy
one just to see for myself.  It’s still standing in
the corner, I might use it some day. 

Also, I have had some more recent discussions with
other folks who investigated T-8 lighting.  Their
conclusions were a little more positive than what I
came up with.  Here is another opinion – “My rule of
thumb is that you get 20% more light for 1/2 of the
electricity, and the lamps last 5 times as long.”
Good luck!


newellcr at yahoo_com

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