Abstract
Electricity theft and illegal connection by ground surface conductors is a pervasive problem in South Africa. The impact this phenomenon has is not only limited to revenue loss and equipment damage, but more importantly it presents a life hazard. Although the issues of non-technical losses have been researched for decades, no universal solution has been presented due to the complexity of the problem. This paper investigates the application of zero-sequence current-based detection as a mitigation strategy to deal with illegal connections by ground surface conductors. Simulation and experimental results show the validity of this technique as well as its dependence on seasonal change of the soil resistivity.