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T-8 lamp and ballast questions (Looooong post)

Hello Folks, 

I put in many, many, additional hours of searching 
after I posted my series of questions and received 
Bill’s reply. (Thank you Bill!)  I used the formulas 
from the Advance web site “Specifications/Terms” 
section to develop answers to some of my questions. My

original desire was to upgrade my $7 shop lights by 
replacing the cheapie ballast with an electronic 
ballast to get the energy savings. That’s still what I

want to do. I started to run the numbers.  I couldn’t 
find actual numbers for my cheapie ballast so I used 
numbers from an Advance magnetic ballast (TM 2540-TP) 
http://www.advancetransformer.com/ to approximate it. 
This Advance ballast is probably more efficient than 
my $7 shop light configuration.  So I consider this to

be a conservative comparison so my electrical savings 
should be higher, but probably not by much.

My first question “1. Sylvania’s website indicates 
that their .88-.90 ballast factor units provide a 30-
40% cost savings over 40 watt T12 bulbs. In generic 
terms, how does the light output of a 32 watt T-8 with

electronic ballast fixture compare to cheap shop light

T-12 40 watt fixture?” 

The answer that I came up with is: The Magnatek 
B232I120RH (two bulb T-8 ballast available at Home 
Depot) gives 106% of the lumen output and uses only 
64% of the energy (based on input watt values 
and “average” lumen output from the tubes) of the 
cheapie ballast. To re-run this using the “initial” 
lumen output from the tubes gives the results that the

electronic ballast set up gives 100.4% of the lumen 
output and uses only 64% of the energy.  This assumes 
(at least) several things – 1. Use of similar bulbs 
(GE F32T8/SP41 and F40/SP41/RS/WM), 2. I applied the 
formulas correctly, 3. I read the specifications 
correctly, and 4.  The incorrect assumption is valid -

that the T-8 and T-12 tubes perform similarly across 
their 20,000 hour life (They don’t the T-8’s provide 
better lumen output across their life so this is again

a conservative assumption). There are a lot of BIG ifs

here, but I’m reasonably confident. I think that the 
bottom line here is that you should expect at least as

much useable light from your T-8 lamps as compared to 
the T-12 lamps even thought the wattage is less.  BTW,

Here’s magnatek http://www.magnetek.com/ballast/  

My third question “3. Jamie Johnson asked in 1999 “It 
seems the instant starters produce more lumens/watt, 
but with a reduction in lamp life, which is ok, I 
change every 6 months…” His question wasn’t answered 
as far as I can tell from the archives. Do the instant

starters produce more lumens/watt? Is it 
significant? “ 

The answer that I came up with is: According to the 
advance site comparison of “Instant Start vs Program 
Rapid Start” document for their Centium Instant Start 
Electronic Ballast. IS uses 7% less energy than the 
Centium RS ballast. That’s significant IMO. The 
negative to this is that IS will reduce lamp life. 
This is insignificant according to the same document 
unless you plan on cycling your bulb off and on for 
more than 10,000 times. That’s over 27 years worth of 
off/on if you do it once a day. Plan on replacing your

switch also if you do this.;-) 

My fourth question “4. Where can I buy the ballasts on

line and who has the best prices?” The answer that I 
came up with is: http://www.gesupplylight.com/ The 
same ballast at Home Depot might be cheaper here on-
line. It depends on how many you need and which 
ballast (2, 3, or 4 bulb model) you need.  Don’t 
forget to add shipping costs. Exact Home Depot pricing

escapes me but the ballasts are roughly $20, $22, and 
$29 for 2, 3, and 4 bulb models respectively.

My fifth question “5. Just out of curiosity, has 
someone already done the legwork of finding the 
cheapest .88-.90 electronic ballast for either a two 
or four bulb model from an on- line retailer?”

Here it is.  If your main goal is to save electricity 
cost without sacrificing useable light, just go to 
Home Depot and buy an electronic ballast for your 
needs. Then refit your light fixture with this ballast

and expect to get similar or better useable light 

If you are trying to do something exotic (like 
overdrive your lamps), go do your homework and do a 
comparison.  If you use the 3 lamp Home Depot model 
(Magnatek B332I120RH, ballast factor .98 in this case)

to run two t-8s (F32T8/SP41), you will use 12% more 
energy for a useable light gain of 4% compared to 
using the 2 lamp Home Depot model (Magnatek 
B232I120RH) with the same two bulbs.

I’ll save $.81/month per shop light with the Home 
Depot electronic ballast vs the old cheapie light on a

calculated $2.25 ($.07 per kilowatt-hour energy cost) 
per month per shoplight in energy costs.   That works 
out to about $.02/month in savings for each hour I 
spent researching this.  Let’s hope I live a long

I’m not an electrician, but I play one on the 
internet… Double-check the specs and wire it up 

Good luck!


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