Considerations about Fault Loop Impedance Measurement in TN Low-Voltage Network

Loop testing is one of the most difficult measurement performed, day to day, by the electrical technicians. Choosing the tests methods, correlation with instrument accuracy and understanding the external factors that influence the measured result are challenges that the electricians have to deal with. This paper presents some considerations about the equivalent fault-loop circuits, in terms of proximity to the distribution transformer and particularly configurations, TN-S or TN-C networks. We analyzed the measured parameters and successive tests to be done, possible sources of errors and in the final stage the conclusion regarding the network security degree.