T8 vs. T12 Lamps

One of the most common questions we receive at Adventure Lighting is, should I upgrade from T12 to T8 lamps

Here’s the rundown on why this is a no-brainer. T12 Lamps are being phased out of production.  I’ve heard that 2012 will be the last year they’re made. Now, I’m sure the lamps will still be available, but there are reasons why they’re going away. 

A standard 4 lamp fixture, similar to what most every office in America uses, has a standard 40 watt T12 lamp on a standard magnetic ballast (which won’t be produced after June of 2010) and uses 172 watts of energy.  The same fixture retrofitted with T8 lamps and a new electronic ballast uses 112 watts of energy – that’s a 35% reduction in energy usage!  To retrofit an existing fixture with the new ballasts is a simple process that requires very basic wiring knowledge.  Remove (2) T12 ballasts, replace with (1) T8 ballast, and replace old lamps with new ones in the same sockets.

Find out how to save money on your lighting!

Not only are you going to see a 35% reduction in energy consumption, you’ll also see a dramatic difference in light output.  The Standard T12 lamp produces 2,650 initial lumens per lamp.  The standard T8 produces 2,800 initial lumens per lamp, 6% brighter.  But the standard T12 lamp produces 2,300 design lumens and the T8 produces 2,660 design lumens.   


Initial lumens –  the average lumen output of the lamp after 100 hours of operation under controlled lab conditions. 

Design Lumens are the average lumen output of the lamp after 40% of its rated life. 

You can see that the T12 lamp loses 14% of its light output over the first 40% of its life, whereas the T8 only loses 5% of its light output.  Combine that over 4 lamps and you have a loss of 1,400 lumens per fixture as compared to 560 lumens lost on a T8 fixture. I’ll get into why the T8 lamp is a better lamp as far as color later – but the 35% energy savings and a better lumen maintenance are 2 of the reasons why switching is better. 

Let’s say your office runs those fixtures 12 hours a day, 5 days a week.  At an average energy cost of $0.07 per KWh you’re looking at a savings of $13.10 per year.  If you have 50 fixtures in your building, that’s a savings of $655.00 per year. And by the way, MidAmerican Energy gives you a rebate of $18 per fixture to do this.  $54 dollars if you have an audit done. (We’ll get into this at a later post.)

Find out how retrofitting your lights can save you money!

I think I’ve made a compelling argument as to why upgrading from T12 to T8 technology is a no-brainer.  Call us and let me come out to look at your situation to give you a free assessment of what can be done to upgrade you today! 

Brian Huff, along with Jack and Sue, own and manage Adventure Lighting in Des Moines, Iowa. To find out more, visit www.adventurelighting.com.


85 responses to “T8 vs. T12 Lamps”

  1. Joe Mass says:

    This evaluates energy vs T12 40W. People do not use those anymore, they use 34W T12. What is the energy savings then?

  2. Good question. This is mostly true, however most people are still using magnetic ballasts. When using this ballast, the actual input wattage of a T12 – 34 watt bulb on a two lamp fixture is 72 watts. It is 86 watts on a when using a 40 watt T12 lamp. So yes, there is a significant savings when using a 34 watt bulb versus a 40 watt T12. A typical 2 lamp T8 fixture using standard 32watt lamps uses 59 input watts. This is an 18% energy savings on a 120v system. The T8 lamp will also have an extra 4,000 hours of average rated life on a 3 hour start cycle, and a couple hundred extra lumens per lamp. Plus in most states there’s a rebate from the energy company for upgrading to this technology. If that’s not enough, the T12 lamps are being outlawed in 2012 by the EPA. (Although, I’m sure you’ll still be able to find them)

    • Just wanting clarification on your numbers.
      Are you assuming 28 watt or 32 watt T8 bulbs.
      Are the T8 bulb “Hi Lumen” output?
      And are you using .88 ballast factor for the t8 verses the 1.0 for the t12 magnetic?

  3. I like your explainations, simple, clear and to the point! thank you for being good writers!

  4. Jason says:

    What about 28 and 25 W T8 lamps in a 2 lamp fixture? What is the actual energy consumption?

  5. Jason says:

    And is your first example with the 4 lamp fixture using 32W bulbs? What about 28 and 25w? I’d like to know.

  6. ray miller says:

    hi, my mother has a t8 4 bulb fixture using t12 36w bulbs for 4 years now. the ballast has gone bad but never had to change a bulb. is this ok to do, do i need to replace t12 bulb with t8 with new t8 ballast. in the dark right now. thanks for your responce goat.

    • Thanks for the question. If you’re currently using t12 lamps and a t8 ballast, I’m surprised it has lasted as long as it has. The lamps will work for some time, but are not designed to work with a ballast that doesn’t match the technology. I would recommend getting 4 new t8 lamps, and a 4 lamp t8 ballast. The t8 lamps are higher quality, not only with more light output, but with a higher color quality and average life rating. This isn’t a large investment, and can be picked up at any hardware store. I, of course, would reccmmend buying from a local lighting distributor who can help you select the proper color temp and lumen output of the new lamps for your application.

      Please get back to me if you have any other questions I can answer.

      Brian Huff
      Sent from my iPad

  7. ray miller says:

    Thanks Brian for your reply. My mom has two of these fixtures one is still functioning properly, the bad one I replaced the ballast and installed T8 bulbs. I’ll wait until the other one goes bad to replace that ballast. Thanks again. Ray

  8. Lonnie E. Caudill says:

    Are t-8’s going to be phased out and replaced with LED tubes?

    • There is no word of that happening anytime in the near future. Eventually, maybe. Right now it’s just the T12 tubes going the way of the buffalo. LED tubes are just starting to become a viable option. But still only if you can afford to buy them… And they are EXPENSIVE.

  9. Robert long says:

    HI : I have a shop with apprx 60 2lamp vho t12 110 w bulbs, I installed these when the building was built and have had constant problems with them. currently our electric supplier has energy credits which I may choose to take advantage of but I don’t know what lighting choice to use. I am knowledgable about lighting , lumens,cri ,ect . This is a large auto repair facility which we originally spec’d for 100 candle pwr at the work level with 16ft ceilings . I have had constant ballast problems, lamp problems ect no matter what brand or cost I have used . I had GE engineers out , electric company techs out, no one has solved the problem for 30 yrs . I really need a solution .

    Bob , Chicago

    • Bob-

      I’m sure you’ve already looked into this, but is your power consistent? It sounds like there may be a voltage spike killing ballasts. If you’ve checked that, and I assume you have, I’d look at getting away from the T12 VHO. It’s a rather finicky lamp type.

      If you’re actually looking at a new system, we usually put 6 lamp T8 High Bay fixtures in auto repair shops. They put a NICE punch of light to the work area and don’t use a ton of energy. The fixtures use a more reliable and better tested (read: more common) type of ballast and lamp combination. We’ve had nothing but good luck with them. There is also likely a rebate available from your energy provider. If you would like to send me the dimensions of your facility I can run a foot candle calculations CAD Drawing to see how many fixtures you’d need to get to your desired 100fc level. However, I’d recommend putting 1 fixture up to see if it does everything you want it to do first.

      Thanks for the questions!
      Brian Huff

      • Robert long says:

        Brian: Thanks for the response . I have to do something as we are at a stage where the lighting needs service badly and after reading some data online it seems like we originally relied on a contractor to decide the lighting layout and I am not sure it was ever really optimal for what we do! On its best day we had good general light but undercar and in between car lighting has always been poor. We have always used drop lights under car and under hood but this also is poor at best and maintenance is terrible. How do I go about getting someone to look at the situation and perhaps come up with the best all around best case situation. The building is 8700 sf irregular rectangle with a outcropping office in the front south and another outcropping at the north rear (longer bays for truck repair) 5 doors rear and 5 doors front all drive in bays. overhead lighting is going contrary to the bays. I would appreciate any help in thinking through a solution.

        Bob Long

  10. Mike Renna says:

    Home user here, hope you don’t mind answering this:

    I have a light over the kitchen table. 3 fixtures, each with 20w / 2′ T12 lamps (so 6 bulbs total). I feel they don’t give off enough light and I am changing the bulbs every 2 – 3 years. Also, they are daylight, not cool white (too yellow for the kitchen, right?)

    I was just at Home Depot and the guy was talking about T5 bulbs. Is that a better / same option? Do you do retail sales? Do you have T8 or T5 in 2′ length and daylight snd in simple fixtures that just hold the bulbs (no covers /reflectors – there’s a plexiglass 2′ x 2′ cover that covers the 3 fixtures. Or do you think I’ll find those at retail?



    • Thanks for the question Mike- Here we go…
      First, I think we need to make sure you’re talking about the proper color temp. You’re saying that you have Daylight (i.e. 5000k) not cool white (4100k) and that it’ too yellow for the kitchen… One would assume that would be the warmer white (3500k). (5000k – Almost Blue/White light – 4100k Standard cool color you’ll see in most offices, 3500k a warmer tone – more yellow.) There isn’t actually any difference in the light output of a particular lamp for either of the colors, but the eye perceives the higher Kelvin color temps to be brighter. With that being said, if you put 5000k lamps in your kitchen and you have can lights with halogen lamps around it, the colors will be vastly different.

      As far as T5 goes… You won’t be able to simply change out the bulbs and have T5. The T12 lamp and T5 lamp are completely different. You would have to change out the entire fixture in order to get to T5.

      The easiest and probably best change for you would be to move to a T8 lamp. Your current T12 (assuming it’s a daylight) produces approximately 850 lumens. If you were to move to a T8 lamp that fits in the same sockets you would bump each lamp up to 1325 lumens. You will have to change out the ballasts as well, but that isn’t difficult.

      Here’s what you’ll need from any local lamp and ballast distributor…
      3 – ICN2P32N – 2 Lamp Electronic T8 Ballast
      6 – F17T8/TL850 – 5000k Daylight 2′ T8 Lamps (you can pick your color by changing the TL850 to TL841 or TL835) I will say that you might struggle to find a 5000k 2′ T8 lamp. We stock 100,000 lamps and don’t have that one in our warehouse. Your best bet would be to go to a 4100k Lamp. I don’t think you’ll be disappointed.
      Also, several wire nuts, screwdriver, and simple hand eye coordination.

      This shouldn’t cost you more than $100.

      Get back to us to let me know how it went! Oh, and don’t forget to turn off the power.

      Brian Huff
      Adventure Lighting

  11. Ralph says:

    I have a retail store with the t12 light fixtures 3 tube 40w Ballast are dying and I am not sure what to do> I could replace all 40 Ceiling fixture or just change out ballast and tubes. The current lights are at least 15 years old. ? replace fixture or retrofit with T8 and new ballast? If so what ballast would you recommend

    • Thanks for the question Ralph-

      The easiest and least expensive option would be to change out the lamps and ballasts in a simple retrofit to T8 lamps. Using the existing sockets and fixture. The ballast you’d be looking for would be an Advance ICN4P32N (or ICN4P32SC, they change the p/n all the time, no difference) This assumes you are talking about a 4 lamp fixture. You’d be looking for Philips F32T8/TL741 lamps as well. There are a ton of options when it comes to lamps, but this is the best selling, least expensive, most common lamp out there.

      If you take a look at your fixture and see that your sockets are breaking, lenses are yellowing and breaking… maybe it’s time for a whole new fixture. If you see that maybe it’s time to go with a new fixture, there are much more energy efficient fixtures on the market today. New fixtures look nicer than the old, and use less lamps to produce the same amount of light. This is a better option… But it’s also going to be more expensive.

      Good Luck! Let me know if you need to talk it through a bit more.
      Brian Huff

      • Ralph says:

        The landlord says its would be on my dime if I replaced the fixtures, There are three bulbs in the system and for some reason the center one still burns. We have taken the outboard bulbs out and put them in a differant fixture and they work. I guess I’ll at least change out the ones that are bad with new ballast and T8 bulb, cant find a ballast for t12 at any local home center

        • I’m sorry, the ballast I reccomended was the 4 lamp. I meant to say the 3 lamp. (NEED TO PAY ATTENTION, BRIAN.) I’m sorry, the ballast you’d be looking for is the ICN3P32N. That should allow you to eliminate 1 ballast out of your fixture, as the current T12 fixture has 2 ballasts. My guess is that the ballast running the two outter lamps has gone bad. And then the ballast running the 1 inner lamp is still running. The newer T8 electronic ballast will run all 3 of the lamps. Hope this helps!


        • As far as this being on your dime… The lights are going to look a lot better when lit. There will be a significant energy savings that should pay for itself in under 2 years time. And if that’s not enough, look for rebates through your energy provider. My guess is that the basic rebate will cover most of the cost of the ballast. In our area, it would be $14.00. Good luck!

  12. Allen says:

    Hi i’m changing out 8′ T12 with 2- 60 watt bulbs and putting in 4-4′ 32 watt T8’s its a retro fit kit what would be the energy savings

    • Allen-

      Excellent choice! We’ve had a lot of luck with this type of retrofit. It’s also much easier in the long run to stock 4′ lamps, instead of 8′ lamps.

      Thanks for your commment!

  13. Ralph says:

    Does the 3 lamp requirement alter you 4 lamp ballast

  14. Art says:

    Good Morning;
    Can you address the question of T12 vs. T8 tube life?
    I’m hearing from several sources that the T8 tubes require much more frequent replacement than previously used T12s.
    This seems to be a problem for both new installations and ballast/bulb retrofits.
    The speculation is that because the T8s have the greater output, they are more highly stressed, which reduces life.
    Thanks for the information.

    • I would be glad to address this question-

      Without copying and pasting the life ratings straight from the catalog, I’ll explain what I think is happening. You’re going to have to trust my numbers… Though I can back them up…

      The standard T12-34watt lamp that you would find on sale anywhere for around $1.50~ has a life rating of 20,000 hours.
      The standard T8-32watt lamp that you would find on sale anywhere for around $2.00~ has a life rating of 24,000 hours.

      These life ratings are based on a 3 hour start tests, meaning under lab conditions, lamps are turned on for 3 hours, turned off for 20 minutes, turned on for 3 hours, turn off for 20 minutes… and so on until they die. (rough life right?)

      The life rating of a lamp is defined as follows: 100 lamps in lab conditions are turned on and off as explained above. When half have died, that is your life rating. So the issue with life ratings is that even under perfect conditions, half the lamps should have died by the time the life rating is reached. And if you’re turning your fixtures off and on frequently those numbers will drop drastically.

      Reading from the comments above with regards to power consumption and Ballast Factors, T8 lamps under basic conditions are only run at 88% of their capacity, where the old T12’s were run at 100% of their capacity.

      As for why someone is having to replace T8 lamps more frequently than T12 lamps, I’ve never really heard that this is much of an issue. What I have seen in real life, is that the newer electronic ballasts don’t last ANYWHERE NEAR AS LONG as the old magnetic ones that ran T12s. This may be where your information is based. Does that attempt to provide some context to your question? Please let me know if I’m off base.

      Brian Huff
      Adventure Lighting

  15. Confused says:

    Can you explain, how 4 – 32 watt lamps (simple math 128 watts) can use 112 watts of input power. I don’t understand how a electronic ballast can not have some losses, and even can create an energy gain. The ballast would seem to have a 114% efficiency.

    • Excellent question! I’m glad to see someone is checking these numbers! The input power is the actual power used on the grid. The reason the ballast can be so efficient is because it’s only running the lamps at 88% of their capacity. Each ballast has a Ballast Factor (BF). The standard BF for standard electronic ballast is .88. To get the total lumen output of a lamp, you take the (lamp lumens x the Ballast Factor).

      So in essence- the reason the ballast doesn’t use as much power as you would think is because it’s not running the lamps at their full 32w capability, Rather, 88% of their 32watts.

      In contrast, ballast manufacturers use High Ballast Factor ballasts and Low Ballast Factor ballasts. The high BF is 1.18, and the low is .77 (Advance Ballasts, other mfg’s will vary) so you can pair different lamps with different ballasts in order to get the desired lumen output per watt used.

      The best way to get the most Lumens Per Watt (which is important in LEED Certifications) is to use combinations of ballast factors and lamp outputs to achieve the desired light levels in the space. This is where we come in.

      Thanks for the question, I hope I’ve shined some light on the issue. (pun intended)

      Brian Huff
      Adventure Lighting

  16. Chris Meyer says:

    Why do T8 Bulbs cost more that T12 Bulbs?
    BTW, Love all the Q&A here! I’ve learned some things!

    • Chris- This is an excellent question. I had to do some research on this as well…

      Old T12 lamps use what are called “Halo Phosphors”. These phosphors are mined from Limestone. A READILY available resource in Tennessee, Alabama, and throughout the United States. T8 Lamps, all the new T12 lamps, as well as T5 lamps use Tri-Color phosphors. These are much more rare, and therefore much more expensive. As a matter of fact, China mines approximately 97% of the earths Tri-Color Phosphors.

      This gets back to a newer post about the cost of lamps going up due to the prices of Rare Earths going up. China has a strangle-hold on Tri-Color Phosphors, and has actually declared it a Strategic Resource. SO, they get to sell it to whomever they like, without any anti-trust problems. This is why costs of ALL fluorescent lamps are increasing, and will likely increase well into the future. Any further insight is greatly appreciated!

      Thanks for the questions! On a side note, I’ve received calls from all over the country inquiring about this post. There have been some excellent questions, hope to keep it going!

      Brian Huff
      Adventure Lighting

  17. Cory B. says:

    Our whole Office Bldg. is Lamped with 4 Lamp T12 Fixtures. We are Aware of the T-12 Phaseout.
    Our Electrician has Decided to Replace the Magnetic Ballasts(when they go bad) with, Electronic T12 Ballasts.
    Is this a Wise Choice,or as you Stated is it more Efficient to Replace the Ballast with a 4 Lamp T-8 Electronic Ballast.

    • I’m glad you asked, otherwise, you’d be in a world of hurt… If you’re just replacing the Magnetic ballasts with Electronic that’s great, but that doesn’t change the fact that you can’t buy the bulb anymore. Granted there will always be an option in the T12, but right now, they’re VERY expensive. You’d be better served to go to a T8-4 lamp ballast and replace the lamps too. You’d be saving about 30% on the energy compared to where you are now, and the lamps are relatively cheap, and more importantly, still available!

      Good luck!
      Brian Huff

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  19. Jim says:

    The T8 bulbs may have a shorter life if installed where more frequent on/off cycles. The instant on nature fires electons off a cold cathode which increases oxidation of the cathode (dark rings at the ends) thus shorter life compared to the rapid start nature of the old magnetic T12 ballest. If installed in an location that will be turn off and on many times a day expect to replace the bulbs more often. If install in a location where they are only turned on once (office) expect a greater life and better life long light output. I believe this is the same issue with shorter than expected life of many CFLs.

    • Couldn’t have said it better myself. If you do have an application with lots and lots of cycles, LED is the best choice for you. LED fixtures today can offer excellent life ratings, comparable light output and much more control of the light than their fluorescent counterparts. The ability to Dim LED from the switch or by daylight harvesting sensors is an excellent way to save additional energy dollars. On/Off cycles are not an issue.

      Perhaps I’ll do another blog post on this incredible technology…

      Brian Huff

  20. Jeff CHisholm says:

    We own and opperate forty Sonic Drive-In restauraunts in Texas and have used the 2 lamp strip fixtures in each vehicle bay. The strip fixtures are HO and we use F96T12SP65/HO daybright bulbs. We are looking at retrofitting the fixture with a new ballast and the T8 700 series bulb but have learned the T8 700 series will be discontinued as well after two years and will need to user the T8 800 series. We still want a bright 6500K bulb, but can only find a 5000K lamp. What do you suggest we use for the brightest “white” lamp avaliable. Thank you.

    • Jeff-
      You have 2 options as far as I can tell. I’m unaware of a 65k T8 HO 8 foot lamp, so you’d have to go to the 5000k. You shouldn’t be able to see much of a difference… Option #2: When you retrofit, you can retrofit to a Tandem T8 Fixture with a High Ballast factor Ballast. Then you’d need 4x 65k T8 lamps. Once you go to the 4 foot lamp, there are MANY MANY more options on color temperature, light output and wattage. You ought be able to find a 65k 4′ lamp without much of a issue at your local lighting distributor. Make sure you use a High Ballast factor ballast to match the HO T12 fixture output you currently have.

      Call or comment back with more questions or comments!

      Brian Huff

      • Jeff Chisholm says:


        Well, we have finally moved forward with rebuilding existing F40/T12 4’ layin fixtures replacing the ballasts (2) and bulbs. Converting them to the F32/T8/SP65 bulbs with corresponding ballasts. My research shows me the most lumens I can get in the T8 bulbs is 2700 using the day light, or day bright bulb. Do you know of any manufacturers that offers a bulb with a higher lumen rating?

        Thank you for your help,

        Jeff Chisholm

        • Jeff Chisholm says:


          These are 2 ballast, 4 bulb 2’x4’ troffer layin fixtures. We’re swapping the bulbs and ballast to comply with the new law. Currently they are 40W T12 bulbs and ballasts and we are converting them to 32W T8 bulbs and ballasts. We are using the 6500 K bulbs for the whitest light, but can only find a 2700 lumen output compared to the old 40W T12 output of 3000 lumens. I can find 4200-5000K bulbs with a higher lumen but the color is not near what we would like for the interior of the restaurants.

          Thank you,

          Jeff Chisholm

  21. Brandon A says:

    I just built a 30×50 shop with 12′ ceilings. It has white insulation walls and roof. What light do you recommend I use and how many. I was thinking 10 of the 2 bulb t-8’s from Wal-Mart or Lowes. I want to maintain my 12′ ceiling with out losing any space.

    • Brandon-
      I’d recommend you talk to the teenager at Lowes or Wal-Mart and ask them to do a C.A.D. layout of your shop to figure out how many fixtures you need based on IES FootCandle Recommendations for similar shops based on the tasks you’re completing.

      I have very expensive software to do this, and I charge $500 per layout if you don’t buy the product from me. It’s free if you do. Bottom line, go to a professional, not Lowes or Wal-Mart. Better yet, go to a local lighting distributor. I’d refer you to the Buying Local post from a while back…


  22. Eddy says:


    Would like to ask that T8 can be use for Seedling or cloning flowers? ”paper or tomato”

    Thank u

    • I know the T12’s have lamps listed as “Plant” lights, but for the T8’s I’d reccommend a “F32T8/Daylight Deluxe/ALTO 43396-3” from Philips. I think that would get you where you need to be.

      • Eddy says:


        I have been looked up in google they said 32w give 2,660 lumens. so if more W then its gonna give more lumens ? i would like to know how its work

        thank u

        • Fluorescent lamps don’t simply have higher wattages and more light. (Though there are some exceptions, just not in this case) That lamp is the best you can do, based on the fact that it’s a 4 foot T8, “GROW” lamp. With that being said, you can use a High Ballast Factor Ballast to drive the lamp at 1.18x it’s rated output. Or 3138 lumens. The details are in the comments of this article, “#15 from Confused”.

          Brian Huff

      • Eddy says:

        All right thank u so much Brian

  23. Norm Siebenthal says:

    It seems everyone assumes that existing T12 installations use magnetic ballasts. I have 6 preschools that were built withion the last 20 years with 4 bulb 32 watt T12s and rapid start electronic ballasts. Each school has 80 to 100 fixtures. T12 32 watt bulbs are getting scarce but so far no one has reliably said that I can’t replace the T12 32s with T8 32’s on the existing T12 electronic ballasts and sockets. I’ve replaced a few with T8 ballasts and bulbs when one of the ballasts failed; its about a 20 to 30 minute task. Not a big deal unless you have 600 of them to change. I’m going to experiment with just changing out the bulbs. Will this really not work?

    • Norm-

      I see what you’re saying, and the answer is Yes, It will work. BUT, the lamps will not perform to the specs they promise as far as life, and lumen output are concerned. The ballasts aren’t designed to run them, and therefore will not last as long as they otherwise would. And you’d be voiding any kind of warranty you have on the lamps and ballasts.

      Also, the I think you mean “34” watt T12’s, not 32 watt. These supersaver T12’s have been in use for quite some time. And to my knowledge no longer exist. The Government has banned them as of June of last year. If you can find them, I’d buy them while you can. WE stock a Philips T12 replacement that meets government efficacy standards, and works just like a T12. Same look, same ballast, no need to change anything. These replacement lamps are double the price of the old lamps.

      I can understand that you don’t necessarily want to change all the ballasts out in your 600 fixtures. But, by just replacing the lamps you’re going to be replacing them 4 or 5 times as often, and you won’t be getting a rebate from your utility (if available).

      The choice is yours. It will work, but not very well. And you’ll likely spend more in maintenance over the next couple years than you would have if you’d have done it right the first time.

      Brian Huff

      • Ralph says:

        You might want to check with your local power company on sharing the cost of conversion, we did with our small store and our final cost for all the fixtures and bulbs was less than 400 or $10 per fixture

      • Norm S says:

        Yes. T34 is correct. Unfortunately, no rebates here. I intend to replace ballasts as they fail but can’t do them all at once. I’ll keep a log of bulb failures so we’ll see how much of an impact this will have on wanting to accellerate the ballast changeouts. I have two newer schools that already have all T8 34 watt systems and they fail much more than the existing T12s do. I’ve replaced almost every one of the T8 ballasts in a ten year old school due to failures and the bulbs seemingly go twice as fast as the other schools with T12’s.

        • My theory is that the manufacturer’s design the lamps and ballasts to fail soon after the warranty is up… But it’s just a theory. My question to you is… Do you use occupancy sensors in your new school? If you do, and you don’t have the lamps on “Programmed Start” ballasts, then you will see MANY MANY premature failures. The on-off cycles are what kill lamp life. In schools, teachers often turn the lights on and off and on and off all day long to get the attention of kids, or occ sensors do that for you… If you’re not using programmed start ballasts, then you can have some serious life issues with regard to lamps.

          Good Luck!

  24. Rob says:

    I have a T12 single tube and fixtue situated in kitchen with no more strip light spares as back up. The light is W40/35.
    If I retain the fixture but move to a T8 what combination of light and starter motor is required. If there is other work involved, please advise accordingly.


    • Hello Rob-

      I think what you’re looking for is a 1 lamp T8 Ballast. The Advance Version would be a ICN1P32N. You don’t use the existing starter on these electronic ballasts, so you’ll have to wire around it. I’d recommend looking at the wiring diagram on the ballast to figure out how to wire. Then you’ll need 1 T8 Lamp as well. Since you have a 35k lamp, I’d recommend a F32T8/TL835/alto from Philips. This is a nice high quality lamp and ballast combination. You shouldn’t spend any more than $25 for these two items. And of course, I’d want you to go to your local Lighting Supply/Electrical Wholesale Shop. NOT a big box store.

      Spring is almost here!
      Brian Huff

      • Rob says:

        Dear Brian

        Many thanks for your advice, especially the bit about using a professional outlet. After sending you my e.mail I did come across a UTube video showing the business of rewiring ballasts for a T8 and now realise there’s much more to this than I first thought. Unless I get my hands on a T12, your advise is the perfect alternative rought:)

        Thanks again for a great service.


  25. rgmcadoo says:

    Reality check: the T8 lamps I find are only 2715 lumens each at 32 W while the T12 lamps I use are 3350 lumens at 40 W. T8 lamps DO NOT produce more output than T12 bulbs, and they are only SLIGHTLY more efficient. T8 efficiency = 2715/32 = 84.8 lumens/watt. T12 efficiency – 3350/40 = 83.8 lumens/watt. That’s only an increase of 1.2% efficiency – nothing to crow about. Plus, above it was stated that the T8 ballasts only run the T8 lamps at 88% capacity – THAT’S how they are further reducing the energy usage! So really, the T8 output in use is only 2715 x 0.88 = 2389. So, 4 T12 bulbs is giving you 3350 x 4 = 13400 lumens for 172 W and 4 T8 bulbs are giving you 2389 x 4 = 9556 lumens for 112 W. Yeah, a lot less energy consumption with a lot less light output – go figure. So, in real terms this is 71% of the light output for 65% of the energy – yes there is SOME efficiency increase, but not as much as they would have you believe. Really, they are just forcing us to use lower wattage bulbs. What will happen? You will replace your T12 fixture with a T8 fixture, find out you don’t have enough light and add a SECOND T8 fixture. I’ll let you do the math on that one (hint: you will be using MORE electricity than you were with your old T12 fixture).

    • rgmcadoo-

      I will agree that your math holds water. But I’ve never seen a T12 lamp that has 3350 lumens. The Highest Output I can find is a 2600 initial lumen lamp. (2250 design lumens) @ 40 watts. The only 4 foot T12 lamp (that I can find) that is anywhere close to those lumens is a F48T12/CW/HO High Output Lamp. This lamp is rated for 3400 lumens at 60 watts. But we’re talking apples and oranges.

      I’ve replaced thousands of fixtures full of T12 lamps, and I can assure you that when the lamps are replaced, not one person has ever told me there isn’t as much light as there was with the T12’s.

      I’m sure you’re not wrong on this lamp, but I think we’ll agree to disagree on this one.

      Brian Huff

      • RODGER MCADOO says:


        Thanks for the reply.  The lamps I have been using (the only ones that work for any length of time in my cheap shop light fixtures – yes, lesson learned) are GE Premium Cool White F40T12, #71744.  Packaging says: 3350 Lumens, 40W, 4100K temp.  Don’t know what to tell you – I’ve never measured them, but that’s what GE claims.  The search for replacement bulbs is how I found your website.  Now, instead of replacing a few bulbs, I will now be replacing 18 fixtures AND getting new, more expensive bulbs.  Thanks, Uncle Sam.  I could have paid for a lot of electricity using those “inefficient” T12 bulbs for what this is gonna cost me.  But I guess the important thing is somebody somewhere got a gold star, a grant, and a promotion for “helping” us average idiot Joes out here!

        Anyway, you can agree to disagree, but the fact remains that the American people (those without any electrical background anyway) are being duped.  They are told over and over again that new things are “more efficient.”  Some are, some aren’t.  When output goes down as well as input, nothing is saved.

        Those people who have not complained to you about not having as much light have probably been told they have the same amount and believe it – I bet none of them have ever done a side-by-side comparison.  Plus, I do understand that the new T8 fixtures have been designed to be more efficient, which probably helps, but then, they could have redesigned T12 fixtures, too.

        I am getting tired of the government telling what is for my own good.  Gee, those CFLs work great for porch lights if you live somewhere it never gets below 50 degrees – but not where I live!  Plus, I have not had any indoor CFLs yet to last any longer than an incandescent, some even less!  And on the subject of CFLs, my eyes can tell me for SURE they do not output an “equivalent” 40, 60, 75 or 100 incandescent watts!  If you don’t believe me, do a side-by-side comparison with the same fixture – I have.  Where I had used 40W incandescent bulbs in the past, I find I need to use at least 60W “incandescent equivalent” CFLs.  I don’t care what their testing says – I’m not an expert, but I am aware there are many methods to measure light output and using a different method can give you an “equivalent” output.  But the real test is a side-by-side, equal method comparison with your own eyes!  BTW, I do have some experience in light output measurement; I did extensive acceptance testing on the space station “porch lights” as we called them.

        I hope you see my point.  I’m not blaming you, but I would like to see more truth about these things instead of everyone just “drinking the Koolaid!”

        Thanks again for your time if you read all of this.

        Sincerely, Rod McAdoo


  26. William Butler says:

    Hey, I have 3 fixtures with 2 4′ foot T12’s in them, there atleast 12+ years old, I just recently replaced the bulbs as the old ones were dim and flickering madly, and probably as old as the fixtures… But now my problem is the fixture in the middle will sometimes not come on with the other two, like it will come on very dim and just sort of stay dim for about 5 seconds, and then it will come on. I am wondering, is that just normal for old magnetic ballasts, or is the ballast starting to go bad? Also one other question, the bulbs that were in the fixtures previously were mostly 34 watt, and a couple of 40 watt bulbs, I put all 40 watt bulbs in now, they said “Universal Bulb” on them, which led me to believe that they would work in any T12 fixture, but after discovering that many of the bulbs were 34 watt, I am wondering if it was a 34 watt only fixture. Did they ever make a 34 watt only? Would my 40 watt bulbs be lighting up if it was 34 watt, and also if it is a 34 watt ballast, would it be alright to just leave the bulbs in there till it fails? (bulbs were cheap, planning on T8 replacement when time comes). And just one last thing, do you know where I might be able to find American made T8 fixtures (or atleast ballasts…), as these T12 fixtures as well as the rest of the T12’s in my house have all lasted atleast since I moved here 12 years ago, and I would like to replace them with something that will last equally as long.

    Sorry if that’s a lot of questions, its just difficult to find somebody knowledgeable on lighting. Also just a random question, not sure if you have any experience with HID lighting, but I have a 250 watt mercury vapor light running on a 250 watt metal halite ballast (which the company I bought it from assured me it would be compatible), and I noticed on the 250 watt MV bulb spec sheet it calls for like 225 volt open circuit voltage, and my ballast appears to be giving 278 volts at startup, would you think that would be shorten the life or cause any adverse effects with the MV bulb? (It goes down to ~130 volts once its warmed up). And how warm should a ballast like that get, it gets around 160+ degrees when running for a couple hours, should I be concerned about that, or is it normal to get that hot. I know you will probably tell me just to put a metal halite bulb in it, but for my application I very much prefer the light that a clear MV bulb puts out, and I haven’t been able to find anything that replicates it. Thank you!

    • William Butler says:

      Oh and also one other question relating to mercury vapor lights, do you know if a clear mercury vapor bulb puts out any harmful UV (as in to much to be around), with an intact outer bulb of course. I have had some trouble finding the answer to that on google, but I thought maybe being in the lighting industry you might know that answer. Thank you again.

    • Wow, that is a LONG list of questions… I’ll start at the top…

      1) I think you have a bad ballast. I’d replace with a 2 lamp T8 ballast and T8 lamps.
      2) The original T12 lamps were 40 watts. Manufacturers made a 34 watt “energy saver” T12 lamp for many years. That lamp is no longer produced. We carry a “supreme” 40 watt T12 lamp that would work for your application. But back to answer #1 – you shouldn’t even use these lamps any more.
      3) You will struggle to find American Made Fixtures in any Big Box Store. You’ll want to go to your local Electrical Distributor. They’re available, and of course more expensive (for the most part). But they are generally higher quality. As for ballasts, you will not find a ballast made in the USA. Advance makes theirs in Mexico. Close enough? My theory on ballasts won’t help your quest to buy a long lasting ballast. I’m convinced that the manufacturers of the Electronic Ballasts have programmed them to fail after the 5 year warranty is expired. They certainly don’t last as long as the old magnetics, but you don’t have an option. Those aren’t made any more.
      4) Mercury Vapor Bulbs – You’re right, I would say use a Metal Halide Bulb. But I get it. When you start talking circuits and voltages and electrician lingo, you lose me. I just sell the stuff. You’ll need to check out the H.I.D. Troubleshooting Guide from Advance. You’ll be looking for the 250w Metal Halide testing procedures. If all tests out correct. The Mercury Vapor lamp should work just fine with your Metal Halide Ballast.
      5) H.I.D. ballasts do run very hot. I’m not sure what the actual temperature is, but it’s hot. Nothing to worry about.
      6) As far as a Mercury Vapor bulb putting out harmful UV. That’s one I’ve never heard. What exactly is the concern here? I assume you’re not using it to Tan. You should be fine so long as you’re not staring into it from 12 inches.

      Hope I nailed this quiz!
      Brian Huff – Adventure Lighting, Des Moines, IA. 515-288-0444

      • William Butler says:

        Thank you very much for the prompt answer, and for the detailed answers, my field of expertise is more in DC and computers, so I am a novice when it comes to AC and florescent and all that. And I had thought it might be a bad ballast, good to know I didn’t put the wrong bulbs in. I will probably leave em until they fail, as they do atleast light up eventually haha. You will definitely be first on my list when I go to replace them though, after how helpful you have been. Sad that they don’t make American ballasts anymore, I would gladly pay the extra price for something that would last. Oh well though. And thank you for the help on my HID lighting, its good to know the heat is normal, I didn’t wanna fry anything. As to the UV my only concern was that the box the bulb came in said not to use where people remain for long periods, and that had me a little concerned,I still won’t be staring into it though :D.

        Well anyway thank you again for the help, its much appreciated!

  27. Larry Eckert says:

    Brian, we have a flourescent sign at our church which has three lamps each 96″. The ballast is a T12 and has Magnetek Jefferson 256-472-100 on the cover. The sign is approx. 10 feet long and approx. 5 feet tall, with plastic front/back, two sided. What would you recommend for replacing the ballast, and possible lights/lamps. Thanks, Larry Eckert

    • Hi Larry-

      Signs are a bit of a different breed. The style of lamp you have is a T12HO lamp. They’re built for outdoor use in canopies and signs. And the ballasts that run them are built for that as well. You have the option of going to the T8 version of that lamp, but you’d have to change the ballast and re-wire the whole fixture. I see two choices. 1, stick with what you’ve got. 2, replace the entire lighting system with an LED option. This can be done through your local sign manufacturer.

      Hope this helps.
      Brian Huff

      • Larry Eckert says:

        Thanks Brian. We need to replace the ballast, as the sign no longer lights up. We have checked the power source, new bulbs, etc and have determined the ballast is the problem. Other problem is we cannot locate a T12 Ballast to replace our existing one. Do you know if they are still being made? Some internet research pretty much indicates they were or are being phased out.
        Thanks, Larry

  28. I’ve read through most of the comments here, so I hope I’m not asking something you’ve already answered. I have 14 two-light fixtures that I purchased within the last 3-4 years, not all at once though. I use them for seed starting and have run the T12 bulbs in them. I accidently purchased a case of T8 bulbs and it would be somewhat of a hassle to exchange them for T12’s. What are the main concerns of running the T8 bulbs in the T12 fixtures? Replacing the ballasts sounds daunting to me (I have no electrical skills) plus they are just the basic shop lights – not sure they are worth the time and expense to replace the ballasts. On top of that I don’t really want to dump them (seems wasteful) as I don’t really have the budget to replace the fixtures.

    • Thanks for the question. The T8 lamps will work. They just won’t work for very long. If you would normally see 3 years of operation for the lamp that is supposed to be used, you might see 6 months with the wrong combination you speak of. The lamps won’t be as bright, as they’re not meant to run on the T12 ballast. But they will work for a while. You’ll just have to replace them more often.

      Good luck!
      Brian Huff-

  29. Phil Whitaker says:

    I read through the Q&A during a search for ballast failure causes. The discussions of rapid vs instant start effect on bulb life of T8 vs T12 were enlightening. You’ve also addressed the issue of reduced ballast life in electronic ballasts vs the magnetic ballasts. Does frequent cyling adversely affect the lifespan of an electronic ballast, and are there different classes of replacement ballasts. I have always bought whatever I could find at the local HD or Lowes. I am currently updating my 4ft 2 and 4 bulb T12 fixtures as needed, to T8 ballasts/bulbs. If I could make a “best” choice for T8 ballasts with more frequent cycling, then suggestions would be welcomed. I also was concerned whether the electronic ballast life cycle was shortened by leaving the power applied (switched “on”) after the bulbs are burned out. Thanks for your thoughts on these issues.

    • Thanks for the kind word Phil-
      There isn’t much you can do with regard to a “better” ballast. There isn’t much of a difference as long as you go with a Commercial Grade, name brand. Like Advance (my preference) GE, or Sylvania. You will find a bunch of junk at the local big box stores, those cheap ballasts are built for residential use. And even though you may be using it in a residential application, the quality of the parts will cause the ballast to be subject to pre-mature failure. As with most things, you get what you pay for. With that being said, If you have frequent cycles, you won’t effect the ballast life but you will effect the lamp life. You’ll probably want to go with a Programmed Start Ballast. This will greatly extend the lamp life. As always, I would suggest you buy it at your local lighting distributor. Or call me! I’d be glad to ship you what you need.

      Brian Huff

  30. Bradley says:

    Hello! I am trying to keep some t12 magnetic rapid start fixtures as long as possible – but I realize it may be time to upgrade someday soon. I had just a couple of questions?

    First of all, I would like to go with a t8 “program start” or “program rapid start” ballast. What is the difference between these two? Are they often the same thing but sometimes called differently?

    Secondly – this is pretty important to my application – I’ve heard some rough stories about some commercial grade electronic ballasts putting off a lot of electronic noise that interferes with everything from radio to you name it (and maybe also running hotter than residential). I think I’d like a residential grade ballast that has to adhere to the more strict specs for these reasons? However, I can’t seem to find any PRS or PS T8 ballasts that aren’t just commercially rated and are rated residential. Does such a thing exist?

    Thank you!!! And thank you for maintaining this blog and answering the questions on it so thoroughly.

    • Bradley- Thanks for the question and kind words. Here’s my assessment of your situation-

      There are three different types of “starts” in ballasts, Programmed, instant, and rapid. So a programmed rapid start is still a programmed start. Rapid start ballasts are harder on the lamps that programmed start. You can expect to get longer lamp life from using programmed start, but these ballasts are more expensive.
      Next, The distinction between residential and commercial ballasts is generally the opposite of what you’re saying. The commercial ballasts use better components and thicker wires, thereby adhering to higher standards and generally lasting longer. The radio interference is a separate issue. We’ve seen this 3 times over our years of selling ballasts. 2 out of 3 times a radio frequency filter has been added to the circuit and it’s fixed the problem, the third time, it didn’t work. Now, the programmed start ballast is as high end as it gets, so my guess is that you won’t have any problems, but if you do, the radio frequency filter will likely fix it.

      Hope this helps, Thanks again!
      Brian Huff

      • Lorin Toman says:

        Q: Our Church has a number of 4 lamp, 32 watt T8 fixtures. Approximately 20 are energized in a hallway daily. Wondering if we could remove two of the lamps in each fixture and not stress the ballast?

        • You could do that and the lamps will work for a while. But they will quickly burn out. I obviously wouldn’t recommend this. But it can be done.

          Try changing to a 2 lamp ballast, this will require some re-wiring of the fixture. But you’ll get much better performance.

          Brian Huff

  31. Mark Geitz says:

    I have a machine shop with (10) T12 8 ft 2 bulb fixtures with older ballasts. I believe they are all magnetic. From what I am reading the magnetic starters last much more then the electronic. Also the amount of light produced from the 8 ft T12’s compared to the 4 ft T8’s, I would have to convert them over to (4) 4 ft bulb fixtures. From all I am reading, the minimal savings I would get on the electric usage would not offset the conversion cost (retrofit kit, new ballasts) and replacing ballasts that do not last as long, compared to purchasing and replacement T12 8 ft bulbs as long as I can. The lights go on one time a day, nor constant switching, for about 2800 hours a year. Is this correct?

    • Hi Mark-

      I won’t dispute your logic. It’s generally true that the old magnetic stuff is more reliable, but I would take issue with the fact that it’s brighter. There are ways to make 4′ T8’s much brighter than T12. It all comes down to a cost benefit analysis, and if the costs outweigh the benefits, who am I to tell you that you have to change?

      But here are some things to consider, if you have broken or fried sockets, you’ll start replacing lamps more often. Second, these lamps will become more and more scarce as time goes on. This is because, unlike me, the government has decided that they can tell you what light you have to use. T12 product is being phased out in favor of T8 and LED. Next, you will save energy. Depending on what your energy costs, this alone can pay for the retrofit in a matter of a few years. Finally, if your utility offers rebates for upgrading your lighting, I’d take advantage of them while they’re available. At some point in time you won’t be able to find those lamps and ballasts, then you’ll have no other option but to upgrade. At that time, any rebates would likely be gone. Food for thought…

      Brian Huff

  32. Lorin Toman says:

    Since our new Church opened in 2006, we have gone through 50 electronic ballasts, (Advance 4 tube T-8). We have been installing Sylvania units that have been reliable. Am disappointed in as much as at our old church we had magnetic ballasts and very rarely replaced any.

  33. Donna says:

    Hello – I am wondering why industrial and commercial businesses have changed their T8 8 ft bulbs to 2 T8 4 ft bulbs. What is the benefit as far as energy savings or was it done because there was a suspicion of 8 ft linear bulbs being discontinued?

    • Brian Huff says:

      Hi Donna- More and more the reason for this is because there isn’t an LED 8′ bulb to go into the older fixtures. But previously; 4′ bulbs are cheaper, more reliable, they last longer, there are more color options, they’re easier to transport/ship/take home in your car, and they’re easier to change. They are generally better as far as energy efficiency. 8 foot bulbs are still around, but we sell very few of them these days.
      Brian Huff

  34. Mike says:

    I just leased a retail space and some of the lights were needing replacement. inside of the 4 lamp fixture some lights are on some are off. Some are flickering. Some fixtures have a mixture of t8 and t12 bulbs. I cannot for the life of me find out what type of fixture/ballast it is, a t8 or t12. How would I know which lights to buy and replace? Some fixtures seem interconnected, as when one bulb is taken out or put in, a light in another fixture will start to flicker. Please help.

    • Brian Huff says:

      I think it’s time for an overhaul. You’ll need to take one of the bulbs to your local lighting distributor and say, I need a T8/LED T8 version of this bulb. And a ballast to run them. You could also call an electrician to do this for you. But you need to standardize on one type of bulb and bring all of them up to snuff. Also, check to see if any rebates may be available in your area!
      Brian Huff

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