A dimmable lighting system may replace a bi-level lighting system without having to modify or supplement the existing wiring between a bi-level control unit and one or more light fixtures. The dimmable lighting system may include a dimming controller that may be configured to replace a bi-level control unit in situ (i.e., e.g., in a wall-mounted dual-gang switch box). The dimmable lighting system may also include a dimming driver that may be coupled to the dimming controller via the existing wiring of the bi-level lighting system. The dimming controller may output to the dimming driver a 0-10 volt DC dimming signal referenced to an AC utility voltage. In response, a dimmable lighting device coupled to the dimming driver may output light over a wide range of dimming light levels. Methods of replacing a bi-level lighting system with a dimmable lighting system are also provided, as are other aspects.