A method of monitoring a lighting system which comprises a plurality of lighting units (16, 20) positioned along at least a supply cable comprising: obtaining physical location information in respect of each lighting unit; receiving supply voltage information in respect of each lighting unit; characterized by: based on the physical location information of each lighting unit and the supply voltage information, deriving power network information which identifies cable routes between the lighting units (16, 20); wherein before the step of deriving power network information, the method further comprises the following steps of: clustering the lighting units into one or more clusters based on their physical locations; identifying the cable routes between the lighting units (16, 20) based on supply voltage information within each cluster; and wherein the lighting system further comprises a set of lighting cabinets (98, 108), each lighting cabinet supplying at least one respective set of lighting units (16, 20) along a supply cable extending from the lighting cabinet, and wherein deriving power network information comprises identifying locations of the lighting cabinets along the cable routes by analysis of peaks and valleys of the supply voltages and wherein a gathering of peaks corresponds to a location of a lighting cabinet (98, 108). obtaining physical location information in respect of each lighting unit; receiving supply voltage information in respect of each lighting unit; characterized by: based on the physical location information of each lighting unit and the supply voltage information, deriving power network information which identifies cable routes between the lighting units (16, 20); wherein before the step of deriving power network information, the method further comprises the following steps of: clustering the lighting units into one or more clusters based on their physical locations; identifying the cable routes between the lighting units (16, 20) based on supply voltage information within each cluster; and wherein the lighting system further comprises a set of lighting cabinets (98, 108), each lighting cabinet supplying at least one respective set of lighting units (16, 20) along a supply cable extending from the lighting cabinet, and wherein deriving power network information comprises identifying locations of the lighting cabinets along the cable routes by analysis of peaks and valleys of the supply voltages and wherein a gathering of peaks corresponds to a location of a lighting cabinet (98, 108). based on the physical location information of each lighting unit and the supply voltage information, deriving power network information which identifies cable routes between the lighting units (16, 20); wherein before the step of deriving power network information, the method further comprises the following steps of: clustering the lighting units into one or more clusters based on their physical locations; identifying the cable routes between the lighting units (16, 20) based on supply voltage information within each cluster; and wherein the lighting system further comprises a set of lighting cabinets (98, 108), each lighting cabinet supplying at least one respective set of lighting units (16, 20) along a supply cable extending from the lighting cabinet, and wherein deriving power network information comprises identifying locations of the lighting cabinets along the cable routes by analysis of peaks and valleys of the supply voltages and wherein a gathering of peaks corresponds to a location of a lighting cabinet (98, 108). clustering the lighting units into one or more clusters based on their physical locations; identifying the cable routes between the lighting units (16, 20) based on supply voltage information within each cluster; and wherein the lighting system further comprises a set of lighting cabinets (98, 108), each lighting cabinet supplying at least one respective set of lighting units (16, 20) along a supply cable extending from the lighting cabinet, and wherein deriving power network information comprises identifying locations of the lighting cabinets along the cable routes by analysis of peaks and valleys of the supply voltages and wherein a gathering of peaks corresponds to a location of a lighting cabinet (98, 108).