Patent ID: 7889463

Claim:
A method of preventing non-passive ballast failure caused by overheating in a high-intensity discharge lamp ballast having a primary coil magnetically coupled to a secondary coil, the method comprising: detecting a temperature directly from the secondary coil of the ballast; comparing the detected secondary coil temperature to a predetermined temperature threshold; detecting a current through the primary coil of the ballast; comparing the detected current through the primary coil to a predetermined current threshold; permanently disabling the ballast in response to one or more of a first ballast disabling condition associated with a detected secondary coil temperature in excess of the predetermined temperature threshold and a second ballast disabling condition associated with a detected current through the primary coil in excess of the predetermined current threshold; wherein the step of permanently disabling the ballast further comprises disabling one or more ballast leads having an integral fuse coupled between a power source and the primary coil of the ballast; and wherein the step of permanently disabling the ballast in response to the first ballast disabling condition further comprises triggering a thermal protector with normally open contacts electrically coupled to the primary coil, wherein a portion of the primary coil is shorted by connecting of the normally open contacts.