LED technologies, and in particular industrial LED luminaires, are increasingly entering the industry. Their application in industrial buildings in the food industry is the subject of this study. When reconstructing an industrial building, it is usually envisaged that the lighting will be built with LED luminaires. One of the problems that occur in this situation is the use of electronic starting-regulating devices (LED Drivers), which generate higher harmonics in the power supply network and thus degrade the network parameters. The report presents a long-term study of the harmonic pollution generated by an industrial LED lighting system in an industrial room for the food industry. The study was conducted for a period of 6 months, under different modes of operation of the lighting system and different temperature regimes in the room. The obtained data are summarized and systematized. The report presents the summarized results of the study in tabular and graphical form. It was found that the harmonic pollution resulting from the lighting system significantly exceeds the requirements of the electricity quality standard. Conclusions and some recommendations from the research are formulated.