In this study, a wide-area fault-location (FL) method for power transmission lines is proposed. Impractical installation of modern measuring devices (e.g. phasor measurement unit (PMU)) throughout all network buses, due to lack of telecommunication infrastructures or funds, has imposed problems and a growing concern toward the wide-area FL problem with a limited number of measurement devices. In the most related researches, the optimal PMU placement problem for the FL and state estimation issues is separately studied. Also, the existence of occasional gross errors in the measurement set, due to cyber-attacks and various telemetry noise or failure, can bring about the wrong results for the FL algorithms. In the presented study, a PMU placement scheme is proposed for achieving both state and FL observability. Furthermore, by utilising this scheme, a new FL algorithm capable of contemplating gross measurement errors has been proposed. Faulted lines have purposely assumed unknown. In addition, by employing the voltages positive-sequence components, results have shown immunity in regards to fault type and resistance. Comprehensive numerical simulations on the IEEE 14-bus, 57-bus and 118-bus test systems have demonstrated the effectiveness of the proposed method and provided proof to this claim.