The reliability of power supply for production and life depends on the low-voltage distribution system. The line fault prevention and detection is an indispensable work. Traditional detection methods are to directly access to the meter circuit under test, which would lead to impaction on the circuit structure and result in some security risks. A non-contact technique is presented in this paper. Based on the coupling capacitance and the processing of the signal samples, non-contact detection of the wrong line-connection and the line-damage are realized and experimentally verified, which lay the foundation of realization of systematic and intelligent line investigation.