13.3.1 When 25.4 mm (1 in.) specimens are used, the electrodes shall be 63.5 mm (1⁄4 in.) in diameter, with edges rounded to a 0.8 mm (1⁄32 in.) radius.13.3.2 If the size of the molding does not permit 25.4 mm (1 in.) wide specimens, 12.7 mm (1⁄2-in.) discs or strips 0.5 6 0.05mm (0.020 6 0.002 in.) thick shall be used with 1.6-mm(1⁄16-in.) diameter electrodes with rounded edges.13.3.3 The specimen must extend sufficiently far beyond the electrode edge so that a flash-over does not occur.