Hi,
2 footers driven by 4 footers -- well, that depends what kind of ballast you are using, but there are definitely problems with this method.
1) Strike Voltage. 4 foot ballasts provide a bigger spike that start its lamps. So, if you use the big spike with the little lamps, you get premature damage to the lamps. Ultimately, this means that you tubes won't last as long...1/2 as long as usual.
2) Electronic or Tar. If it is tar...better check if you have fire insurace on your house. Its not a hot idea to do that.
If it is an electronic ballast...better yet...a Fulham Workhorse, then you are in better shape.
Fluorescent lamps work by providing a small current through a mercury vapour tube with a special lining. The vapour causes the electric current or electrons to conduct through the tube. Every once in a while, an electron will hit the tube lining and it converted in to light. If we increase the current passing through the lamp, we increase the probability of an electron hitting the tube wall. That is basically what we are doing.
In practice, the lamp current is regulated by the ballast. In the case of an electronic ballast, the lamp current is fairly constant regardless of what tube/tube size/tube length is placed between the output of the ballast. This was done so that a single ballast could drive a variety of lamps (i.e. save development costs). If we take a electronic ballast that was design to drive two seperate lamps and combine the outputs, we will effectively double the current passing through a lamp. Due to losses and other things, we don't really get double. By increasing the lamp current....we get more light. We also get more heat too...this is a by product of the electron-light conversion.
If you want to do this, my recommendation is to get a Workhorse ballast (something like a WH5). WH5 can drive 3 lamps...maybe even 4 if the conditions are right. For example, if you wanted to drive one 2 foot lamp normally, you would use diagram 14. For a 2x overdrive, you would use diagram 10. For a dual 2x overdrive, you can try diagram 11.
The diagram number references and other info on Fulham are available at
www.fulham.com
Hope that helps. If you are not sure about things...ask questions or get a somebody to take a look at it.
- Victor.
[ 01 June 2002, 22:18: Message edited by: reefburnaby ]