This paper presents the analysis of a downed conductor open circuit fault that occurred in the Powerco distribution network. While short-circuit faults on a distribution system can normally be detected and cleared by overcurrent and earth protection, open-circuit faults are much harder to detect. The analysis based on the method of symmetrical components attempts to demonstrate why conventional protection is unable to detect this type of faults. In addition, a few methods that use modern technologies to detect this kind of high impedance faults (HIF) and their implementation are discussed. These methods include brownout voltage detection, I2/I1 (ANSI 46BC) protection and Arc Sense HIF technology.