|
120 volt works best on 120/240 single phase or 120/208 3 phase power systems. 240 volt works best on 120/240 singe phase or 240 volt three phase power systems. 277 works best on 277/480 volt three phase power systems. 277 takes the least current so you can switch more lights with a 20 amp switch than you can 240 volt than you can 120 volt ballasts. The lamps run the same for each input voltage ballast. The price of the new ballast depends primarily on how many million they made this year of that voltage and model. The more they make the cheaper they get. Unless you get the lamp ballast for nearly nothing the cost of the boosting transformer to use a 277 volt ballast on 240 volts or 120 volts won't pay. Then the old ballast may be less efficient than a new ballast and for sure will have a shorter lifetime left, so the economics are poor. Fixtures with 277 volt ballasts will be surely industrial fixtures, probably of better quality than you can buy in a home center and if they can be bought for less than you'd pay in a home center you could afford to buy 120 volt ballasts easier than the boost transformer and rewire them for the more common residential or small shop 120 volt operation. 120 volt and 277 volt ballasts where one side of the ballast is connected to the neutral can be switched with single pole switches. 240 volt ballasts should be switched with two pole switches (so the light fixture wiring is all cold when off) which are uncommon in home centers. Gerald J.
| 
