Abstract: A monitoring apparatus is included in each street light of a plurality of street lights. Each monitoring apparatus monitors the operation of the associated street lamp and stores data representing the operation thereof. Data is sent from each monitoring apparatus to a monitoring station, via the power supply cables connected to the street lamps, under control of the monitoring station. The monitoring station stores the data until it is requested to transfer the data to an interrogating station. The data is then analysed to identify faulty street lights.