A kit of parts for retrofitting an overhead rail for continuously charging a lift unit along a length of a rail, comprising a conductive tape (114a,114b), a carriage (106) comprising a carriage body (140), at least one pair of support wheels (114a-d) rotatably coupled to the carriage body, at least one conductive roller (156) rotatably attached to the carriage, said at least one conductive roller being upwardly biased into rolling engagement with the conductive tape when the conductive tape and the carriage are installed in the rail, a connector card (160) for electrically coupling the conductive tape to a power source, and a plug adapter and a power supply for electrically coupling the connector card to line voltage. The conductive tape, the carriage, the connector card, the plug adapter and the power supply are packaged together.
