Educate yourself before purchasing. All you need to know about ballasts sizes, energy usage, voltage. I have been asked so many questions about ballasts and I have answered them one by one. I am going to write this to share what I know with you now.

    F40T12 Magnetic Ballast       Latest F32T8 Electronic Ballast                                              

Which one is better? Electronic or magnetic ballast? T12 or T8 fluorescent lamp?

Ballasts are either magnetic or electronic. At least, these two are the ones that I am going to talk about. A few years ago most ballasts were magnetic. These ballasts were bigger in size ( width and height but length is the same as electronic)  in comparison with their newer generation electronic model. They were heavier in weight. They would last less and most they had humming noise ( you could hear the ballast working ). Most importantly, they would use lots of energy. Opposite all these charastristics and you would have electronic ballast.

I want to replace my magnetic ballasts should I change the bulbs too?

When magnetic ballasts were in use ( still are ) T12 lamps which are older generation fluorescent lamps were used along with them. Most people when they talk about F40T12 ballast they mean magnetic ballast which works with T12 fluorescent light bulb and uses 40 Watts. But little by little is getting harder to find magnetic ballasts for T12 lamps since factories stopped making them. Instead they started making new generation of  lamps (T8 lamps) and respectively T8 ballasts and still for replacement of T12 ballasts they had to make some T12 ballasts but they started to make ELECTRONIC T12. Now, we can use F40T12 electronic ballast for F40T12 fluorescent bulb. Eventually magnetic will disappear as T12 is disappearing and every fluorescent bulb is getting changed to T8 which is newer technology in making bulbs. T8 bullbs are thinner in diameter in comparison with older T12 bulbs . Also,T8 bulbs use less energy. Remember, we said earlier that electronic ballasts save us energy and now we know T8 bulbs are saving us energy. How about combination of these two? Before we move on would you answer to the question which I used as the title of this paragraph. Your answer is " yes" since if you use newer technology T8 bulbs then use newer technology electronic ballasts too. Unless, you want to shorten the life of your newly changed electronic ballasts and burn out your T12 lamps.

I used to use F40T12 bulbs what kind of bulb and ballast do I need?

Factories started making 32 watts T8 fluorescent bulbs instead of 40 watts T12 fluorescent bulbs since with T8 technology a 32 watts bulb was producing same amount of light as a 40 watts T12 bulb. As you see we are saving 8 watts of energy just because of a newer model lamp. Now that we have a 32 watt T8 lamp we need a ballast for it. Then we use a F32T8 electroni ballast for it. This ballast is an electronic ballast since it is related with T8 and T8 is newer technology in bulbs and we use respectively

newer technology of ballasts which is electronic. We can make this statement  then that all T8 ballasts are electronic but remeber all electronic ballasts are not T8 since as we said factories had to make some electronic ballasts for replacment of older model T12 magnetic ballasts.95% of the time T12 and magnetic are related and 100% of the time T8 and electronic are related. ( we are not talking about T5 ballast here at all ).

Most ballast cover smaller in length bulbs and also bulbs with lower watts. For example F32T8 which is ballast for a 32 watts T8 bulb ( this bulb is 4-foot in length) also powers on 25-watt (3-foot) bulb which we call F25T8 and also powers on F17T8 which is 17-watt (2-foot) bulb. You can find all compatible bulbs on the sticker on the ballast. This sticker also gives you the Amps that this ballast uses in order to power on the bulb(s). Also tells us how many bulbs this ballast is capable of powering on.

Which ballast is more efficient?

Ex:  (4) F32T8   .84  means this ballast powers on 4 bulbs of 32-watt T8 and it uses 0.84 Amps in order to power on all 4 lamps. On the same ballast if you see (3) F32T8  0.65 means this ballast also is capable of powering on 3  32-watt T8 bulbs and uses 0.65 Amp in order to run all 3 bulbs. Most 4-lamp ballasts are capable of running 3 or 2 or 1 lamp(s) but since we have ballasts that are designed to cover the 2 or 1 section then mostly we say that ballast is 4/3 lamps. You may ask yourself if a 4-lamp ballast covers 4/3/2/1 then why even bother making another kind of ballast which just cover 2/1 lamp(s). The answer is lower price and easier in fixture wiring.

What is HO ( high output) ballast?

Sometimes we want to use a 4-lamp ballast to power on 2 lamps when we need to get more light out of the bulbs. It is like using a powerful 4.0 liter engine which is designed to be used on a car with 4 wheels on a motorcycle with 2 wheels. Of course you transfer more energy to each wheel in the bike case. I do not recommend using 4-lamp ballast on 2 lamps since we are going to shorten the bulbs life. We do have some HO ( High Output ) ballasts that are designed for this purpose (  for either T12 or T8 bulbs) and of course we also use HO bulbs with these HO ballasts. Since HO ballasts and bulbs are expensive some people do use the 4 on 2 as we talked about it. 

What is L, N, or H ballast?

Now that we talked about HO ballasts lets talk about H, N and L ballasts. H is high-power ballast, N is normal and L is low-power ballast. The higher the power the higher the amount of light that you can get out of a bulb. Most people rather L ballasts since they rather to save energy and L ballasts have enough light. N produces more light and you pay more for energy bill and H is for special projects or where you need lots of light. ( either add more fixturs or use H ballasts).

GE, Universal Lighting (Triad), Sylvania and Advance are main brand names. Howard Industries come after in my opinion. These companies make almost the same ballasts but they name them differently. For example GE-432-MAX-L/Ultra which GE makes is the same as B432IUNVEL-A which Universal (Triad) makes. As you see both have letter "L" means both are L ballast or low-power. 

Another example GE-432-MAX-H/Ultra is the same as B432IUNVHP. See both have letter "H" since both are High power.

Don't buy the wrong voltage?

Another thing is voltage of the ballast. Older days we had to make some 120 volts ballasts for residential and small businesses use and then some 277 volt ballasts for industrial uses. Today with new technology we have Dual Volt ballasts that work with both 120 and 277 volts.

Hope you find this guide helpful.  Please vote.  just look below and vote please.