I am not particularly familuar with your particular type ballast. However under the general principles of most ballast designs either of three things will happen.
1. The ballast will fire the lower wattage bulb just like it would the rated bulb.
2. The start sequence will kick in but will not switch to the run sequence because it has not sensed the correct from of current through the tube.
3. The start sequence will cycle but when it switches to the run sequence it will not detect the bulb is burning properly and the start sequence will restart.
Either way if watch it within 3 minutes you should be able to tell which of the above three is occuring. If it lights up nor,mally which I suspect would happen with 95% of the none electronic ballasts then your home free. If not then the ballast is tightly tunned to a specific bulb.
Now if it is an electronic ballast and it does not properly fire some of them have adjustments so they can be tuned to particular bulb. The bad part is that these adjustments are not always readily accessable.
On the side note form others comments. Yes many manufacturers build only one basic ballast for multi applications. In some cases it may be the adjustment of a pot to change the ballast from 2- 24W bulbs to 2-54 watt bulbs, in other it may be a hidden selector switch, and it others it might be electronicly sensed and switched.
The saving between building a ballast to handle 55 watts maximium compared to 150 watts maximium is probbly less than a $1.00 each. Yet the savings by being able to build 10,000 ballast at a time compared to 2,000 is probably greater than $5.00 each. So it becomes a no brainer in many cases. However there are no gurantees as to haw a particlur company will approach this. If they are building millions of ballasts that savings of $1.00 in parts may be atractive as the savings from building 1,000,000 compared to 200,000 may be negliable or only pennies.
Now where you do have a much higher risk is when you assume that the ballast that ran your 1-24W bulbs will run your 2-54 watt bulbs. It might be able to light them up but is it properly cooled or have the heat sinks to handle the added wattage. Will it overheat. or start a fire? or is the same ballast they sell in a fixture with 4-54 Bulbs and will not give you any issues?
Dennis
<a href=showthread.php?s=&postid=9165939#post9165939 target=_blank>Originally posted</a> by RichConley
TropTea, I've got a bunch of these QTP ballasts sitting aroudn, so it'd be a 39w bulb in each 54w slot, so pulling significantly less wattage.
