The present invention is a kit for adapting a tube lamp fixture made for a first size of lamp tubes into a fixture that accommodates smaller lamp tubes. The kit comprises a conversion apparatus that itself comprises a bar in which are disposed one or more plugs for connecting to the sockets in the existing tube lamp fixture, said plugs being slidably disposed on the bar to adapt to the position of the sockets in the fixture. The conversion apparatus further comprises one or more slidably disposed sockets on the opposite side of the bar that may be positioned independently from the plugs. Appropriate wiring permits the supply of electrical energy to the tube lamps. The invention further comprises a master-slave ballast conversion assembly. The ballast conversion assembly comprises a chain of circuit boards connected by cables and connectors that enable a single ballast to control two or more tubes through a chain of circuit boards.