Section 6.2 of ASTM B470 covers the fraying test for bonded copper conductors used in hookup wire. The conductor, cut square at the end, is inserted into a blind hole of specified size and depth.
The edge of the hole is broken to no more than 1/64 inch radius. The conductor is bent 90 degrees over the edge and back to normal position. Hole diameters and depths are specified in Table 3 for each AWG size from 16 to 26.
After testing, no separations of strands shall be visible to the unaided eye from the cut end to the point of bend. This verifies the bonding provides adequate strand cohesion during handling.