I have tried to crimped a PVC-insulated terminal 2.5 mm² on a NYM cable. The terminal can be taken off with a hand. What have I done wrong?
All insulated terminals are made for the crimping of stranded cables. If you try to crimp a solid wire, the force of the tool will be not enough for the deformation of the solid wire, so the crimping will be of poor quality and not reliable at all.