Abrupt Pull Test
This test is to ensure that a pull force on a cord doesn't damage the internal plug terminations. During this test, the plug is mounted in a 45 degree steel plate. The plug blades and ground pin are anchored in the plate. A fixture with a rod, striker plate and a 1.1 kg (2.5 pound) weight are clamped to the cord. The weight is dropped 25 times. During and at the completion of this test, there is to be no loss of electrical continuity (UL 817, Section 12.5).
Underwriters Laboratory (UL) requires the mechanical strength of the plug to be tested by repeatedly impacting the cord at the cord exit. This ensures that a pull force on the cord does not damage the internal plug terminations.