A Grinding Operation Can Cut Multiple Turns of a Resistor Winding

What the evidence preview establishes

Both resistors failed because a manufacturing grinding operation damaged several adjacent wraps of resistance wire and reduced their remaining cross-sections until rupture occurred.

Why this case matters

Preserve and radiograph an open wirewound component before sectioning. Once the open is localized, progressive exposure can distinguish a final electrical melt from the earlier mechanical damage that reduced the conductor cross-section.