Scott35 implied this—but it’s worth repeating. I there is a multi-voltage [tapped] ballast, be certain that only two {of say, five leads} are connected to the {incoming} branch circuit. An example would be a replacement ballast that is labeled 120/208/240/277V. There are often wire pigtails, and on the line side only two should be connected, with the others capped off/well insulated. One of the unused leads accidentally contacting ground or other lead in the ballast case will cook a ballast in short order.
