An electric induction furnace with a lining wear detection system comprising: a replaceable lining having an inner boundary surface and an outer boundary surface, the inner boundary surface of the replaceable lining forming an interior volume of the electric induction furnace; an induction coil at least partially surrounding the exterior height of the replaceable lining; a furnace ground circuit having at a first circuit end, a ground probe protruding into the interior volume of the electric induction furnace and a second circuit end terminating at an electrical ground connection external to the electric induction furnace; characterised by: a t least one electrically conductive mesh embedded in a castable refractory disposed between the outer boundary surface of the wall of the replaceable lining and the induction coil, the at least one electrically conductive mesh forming an electrically discontinuous mesh boundary between the castable refractory in which the at least one electrically conductive mesh is embedded and the replaceable lining; and a direct current voltage source (V dc) having a positive electric potential connected to one of the at least one the electrically conductive mesh, and a negative electric potential connected to the electrical ground connection, a lining wear detection circuit formed between the positive electric potential connected to the one of the at least one electrically conductive mesh, and the negative electric potential connected to the electrical ground connection, whereby the level of a DC leakage current in the lining wear detection circuit changes as the wall of the replaceable lining is consumed. a replaceable lining having an inner boundary surface and an outer boundary surface, the inner boundary surface of the replaceable lining forming an interior volume of the electric induction furnace; an induction coil at least partially surrounding the exterior height of the replaceable lining; a furnace ground circuit having at a first circuit end, a ground probe protruding into the interior volume of the electric induction furnace and a second circuit end terminating at an electrical ground connection external to the electric induction furnace; a t least one electrically conductive mesh embedded in a castable refractory disposed between the outer boundary surface of the wall of the replaceable lining and the induction coil, the at least one electrically conductive mesh forming an electrically discontinuous mesh boundary between the castable refractory in which the at least one electrically conductive mesh is embedded and the replaceable lining; and a direct current voltage source (V dc) having a positive electric potential connected to one of the at least one the electrically conductive mesh, and a negative electric potential connected to the electrical ground connection, a lining wear detection circuit formed between the positive electric potential connected to the one of the at least one electrically conductive mesh, and the negative electric potential connected to the electrical ground connection, whereby the level of a DC leakage current in the lining wear detection circuit changes as the wall of the replaceable lining is consumed.