In electrical power grids NH-fuse-links (gG) are widely used to protect electrical components in case of overloads or shorts-circuit currents. New requirements of modern power grids, especially in the context of a growing share of renewable energies, implicate a much higher thermal stress level of the fuselinks. This can lead to an accelerated ageing of the fuse-elements and can impair the fuselink's tripping behaviour in the area of overloads. Therefore, current research investigates the influence of a higher thermal stress level at normal operation on the functioning of fuse-elements at the border area between rated operation and the interruption of overloads. Therefore temperature rise tests and tripping tests were done with fuse-elements, which have been pre-stressed in additional long-term tests. Based on that results conclusions on possible causes of failures were drawn. Furthermore potential limiting temperatures have been identified, which may guarantee a long-term stable and reliable operation even at higher thermal stress levels.