Fluorescent dimming ballasts

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fisherelectric

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Northern Va
I have a residential job that specs 4' and 2' single tube fluorescent fixtures w/ T8 tubes which are to be dimmed. The lighting designer says she will supply the fixtures but I will need to remove the original ballasts and lampholders and replace with dimming ballasts and rapid-start type lampholders and rewire the fixtures (unless she can find fixtures w/ rapid start lampholders). In addition the ballasts they will supply are for three lamps so I will have to wire three fixtures together on one ballast, I suppose by running flex between them. The dimmer is a 3wire electronic dimmer. The cut sheet notes that "Class 2 sensor wiring must be separated from all power and class 1 wiring..." and that the ballast has terminals for "power wiring, lamp wiring, and EcoSystem bus" in addition to a "class 2 sensor terminal". Does anyone know wether the third wire on this dimmer is class 2 or even what it's for. I believe the sensor terminal is for a different application.
The wiring diagram on the ballast cut sheet says "black (switched) hot, orange (dimmed hot), and neutral" plus the standard lamp wire terminals.
The specs also say the lamps must be "seasoned" for 12 hours before dimming, which I'm not sure what tjhat's about either.
 
-lamps are supposed to be run continuously on high power for a day or two before dimming (I forget the exact reason)

-only sensor wiring we ever ran to dimmer panels was for light sensors so panel could attenuate light based on ambient light (where you might have skylights, outside light, other light sources), but in our cases the sensor wiring went direct to dimming panel so there was no issue (sensor wiring was not contained in luminaires)

-I put in some dimming ballasts and specs said bus wiring was LV, but we ran everything thhn so there was no issue with wiring class/rating
 
the dimming ballast on the job we are on right now are controlled by 24v from a lighting contactor panel designed by watt stopper. In the specs of the job it said the dimming circuit was to be run in seperate conduit. the dimming wires on the ballast are a purple and a gray
 
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nakulak said:
-lamps are supposed to be run continuously on high power for a day or two before dimming (I forget the exact reason)
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I think it has to do with fully evapoating the mercury and/or baking the phosphorous coating. Either way, I have found that the process does increase tube life and, for CFL's, helps the lamps brighten faster after turn-on.
 
If I am understanding you right you are going to use a single ballast with three seperate fixtures. If the dimming ballasts go down to 5% or lower this might not work out since adding extra wiring to reach the lamps will cause capacitive current loss and the three lamps will not be at the same light intensity. If you have to do it this way you should take a carful look at the maximum specified lead length(to the lamps) for the ballast you are using.
 
JKinPA you are right. These ballasts will dim below 5%, however, the maximum length of the ballast to lamp wires is 7' which we should be able to maintain. I am going to run this by the designer to CMA. I appreciate you all sharing what you know. It's hard to beat this forum for great info.
 
fisherelectric said:
Rob you are right....they are using Lutron Hi-Lume ballasts....they provided me the wrong cut sheets. Just curious what the third wire is for.
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The third wire on the ballast (orange) is for the dim leg from the dimmer. You can connect it to the switch leg (black) at the ballast to get 100% light output but no dimming.
 
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