Unaware connection of high pressure sodium lamps to the grid, represent a relevant problem for the grid operators. They have several negative effects in the network, they can overload the circuits and affect the quality of the energy delivered to customers by the injection of harmonics. This thesis aims to answer the question: Can the high pressure sodium lamps connected to the grid be detected through measurements at a centralized location such as a substation? The hypothesis that the lamps have specific electrical characteristics which can be used for its detection, was stablished and validated. Current harmonics and power characteristics of several high pressure sodium lamps were measured. The measured values were used for simulations of the harmonic flow in a low voltage network, and to emulate aggregated measurements combining the lamps with several loads. These calculations were compared with field tests done with high pressure lamps in a low voltage network. The results prove that within certain limitations, in a combination of several loads, the high pressure sodium lamps characteristics can be enhanced in order to be detected and identified from the aggregated data.