Copper Wire Break Photographs Microphotograph Pictures Courtesy of Mr.  L. V. Hai - July, 2006   By Peter Stewart-Hay
Wire Break No. 1 Diameter 0.257mm or 0.0101 inches. This could be a start up wire break. Note the symmetrical cone which is typical of a tension break but the wire also appears shaved, possibly by jogging the machine without lubrication.
Wire Break No. 2 Diameter 0.257mm or 0.0101 inches. This appears to be a foreign inclusion break. Note the damage at the end. No symmetrical cup is present.  
Wire Break No. 3 Diameter 0.257mm or 0.0101 inches. There is no cone here indicating that the wire was likely quite brittle. This could be a foreign material issue say from copper oxide in the rod weld in the wire or perhaps foreign inclusions.
Wire Break No. 4 Diameter 0.257mm or 0.0101 inches. Again this looks like a foreign inclusion break.