In this paper, the correlation between unscheduled power flows in the interconnection lines at the eastern cross border of the European Network of Transmission System Operators for Electricity (ENTSO-E) and multiple electric arc furnace (EAF) operations in Turkey has been assessed. Turkey is interconnected to ENTSO-E at the eastern cross border via Greece and Bulgaria, with a 400-MW export and a 550-MW import agreement. In order to determine the degree of the relationship between the unscheduled power exchange between Turkey and Europe, and the multiple high-power EAF operations, Pearson correlation method has been employed. For this purpose, time-synchronized data of active power consumption have been collected from 17 major EAF plants during 1 week with a time resolution of 3 s, by using custom-design, synchronized power-quality (PQ) analyzers. A total peak-power consumption of nearly 1.5 GW of multiple EAF loads has been recorded. The results obtained have been evaluated by the use of the National Power Quality Monitoring System of Turkey, which continuously monitors the power flows in the interconnection lines of the ENTSO-E by PQ analyzers. The rate of change in total EAF power consumptions higher than 200 MW in less than 15 s against the rate of change in area control error (ACE) index is found to be closely correlated to each other, with a Pearson correlation coefficient (CC) of 0.8. Since the response of the frequency restoration reserve of power plants is much slower, such rapid fluctuations in the power consumption of multiple EAFs collectively result in uncontrollable power flows in the interconnection lines at the eastern cross border of ENTSO-E.