A sill and door jamb assembly providing an opening in an electric arc furnace, the sill and door jamb assembly having a sill block assembly and two jamb block assemblies. The sill block assembly having side-by-side sill blocks, each of the sill blocks being positioned side-by-side to form the sill block assembly and having an upper end and a lower end. The lower end of the sill block assembly is confined within a plurality of courses of the refractory bricks. Each jamb block assembly having a plurality of jamb blocks positioned side-by-side. Each of the jamb block assemblies having a lower end and an inner surface abutting the distal ends of the sill block assembly. The inner surfaces of the jamb block assemblies and the upper surface of the sill block assembly form the slag opening in the furnace.