I talked to a guy who services these booths and lots of others and HE said the problem is the duct size. Fan is 24" but the installer(?) necked the duct down to 12" before it goes thru the sheetrock ceiling. When he lifted the duct offf(while running) the dimming stopped. He said it's likely that the increase in air resistance is straining the fan motor messing up the harmonics and therefore the electronic ballasts. Sound right?
