An adapter plate is provided that fits an existing luminaire in place of an existing globe that mounts to the luminaire. A heat sink mates to the adapter plate and also houses a solid state light engine and associated electronics. The heat sink may provide an enclosed, protective volume for the associated electronics, such as a power supply for the solid state light engine. A globe mounting ring attached to the heat sink allows either an existing globe to be re-mounted or a new globe to be installed.