A structure for TDDB measurement, a method determining TDDB at reduced spacings. The structure includes an upper dielectric layer on a top surface of a lower dielectric layer, a bottom surface of the upper dielectric layer and the top surface of the lower dielectric layer defining an interface; a first wire formed in the lower dielectric layer; a second wire formed in the upper dielectric layer; and wherein a distance between the first wire and the second wire measured in a direction parallel to the interface is below the lithographic resolution limit of the fabrication technology.