The combined ballast apparatus provides dual function, as both slave ballast and emergency battery ballast, without the expense of a dual installation of ballast onto or into a light fixture. The apparatus is further designed for best efficiency in mounting and in service and removal. The mount holes and quick clips provide for installation to existing fixtures without the need for screwdrivers, for example. The quick connects allow the apparatus to be quickly plugged and unplugged from a light fixture, without having to strip wires and use wire nuts or the like. If equipped with the apparatus and needing a ballast change, the fixture is serviced in a matter of perhaps ¼ to ⅓ the time previously required, without the litter.