Patent ID: 6657400
Filing Date: 2003-12-02
Classification: H05B,Y10S

Abstract:
A ballast for powering a gas discharge lamp load, comprising:a circuit ground having a nonzero average voltage with respect to earth ground; an inverter having a DC voltage supply and an inverter output, wherein the inverter is operable to commence operation when a voltage provided by the DC voltage supply reaches a predetermined start up threshold; first and second output connections adapted for connection to the gas discharge lamp load; a protection circuit coupled to the DC voltage supply of the inverter, the circuit ground, and one of: (i) the inverter output; and (ii) the first output connection, wherein the protection circuit is operable, in response to a fault wherein the first output connection is coupled to earth ground prior to start up of the inverter, to prevent start up of the inverter by preventing the voltage provided by the DC voltage supply from reaching the predetermined start up threshold.