This part of IEC 404 is applicable to grain oriented and non-oriented electrical sheet and strip for a.c. measurements of magnetic properties at frequencies up to 400 Hz and for d.c. magnetic measurements. The object of this part is to define the general principles and the technical details of the measurement of the magnetic properties of electrical sheet and strip by means of an Epstein frame. The Epstein frame is applicable to test specimens obtained from electrical sheets and strips of any grade.