A power line carrier (PLC) communication characteristics-based method is proposed for single-phase-to-ground fault location in neutral isolated medium voltage (MV) meshed distribution networks in this paper. The carrier signals with a time-varying frequency and constant amplitude are processed by a set of PLC transmitters and receivers, whose placement is optimized by regarding the power network as an undirected graph. Two signal encoding and decoding algorithms for the PLC terminals are proposed to avoid using expensive timing systems between the terminals. The fault location technique is implemented by comparing the cosine similarity of amplitude attenuation (AA) and phase offset (PO) between the fault and a library. The node corresponding to the maximum cosine similarity of the characteristics between the present fault and the library is selected as the location of the current fault. Only one set of low-cost PLC communication terminals and the widely available power lines are needed in the fault location system, making this approach highly practical. Numerical simulations using MATLAB/Simulink have been performed to verify the technique’s feasibility. The results show that the method can accurately locate faults in neutral isolated MV meshed distribution networks. Besides, the presented approach achieves high accuracy in estimating transition resistance values.