Faults that occur on transmission lines are relatively more common in countries that have extreme weather. Most faults in such countries are caused by lightning storms. For long distance transmission lines, it takes a long time to find the faulted point. This not only prolongs the time of removing and recovering the fault, but also increases economical damages. If fault can be precisely located, maintenance crew can reach the faulted point quickly, and remove the fault in time. So the precise locating of the faulted point on a transmission line is very important to remove fault, improvement of system reliability, and decrease of economic damages as an inherent consequence of a long term outages. Hence, the fault location methods become of much importance for utilities and researches. In this paper, three of single-terminal impedance-based fault location techniques will be investigated to show the reliability and deficiency of each technique.