16.13 Conduit knockout and twistout
16.13.1 The following test shall apply only to conduit entries and shall be performed on a sample securely
held in place using the test apparatus described in Clause 19.23.
16.13.2 A force of 44 N (10 lb) shall be applied to a knockout for 1 min by means of a 6.4 mm (0.250 in)
diameter mandrel with a flat end. The force shall be applied to the exterior surface of the knockout, in a
direction perpendicular to the plane of the knockout, and at the point most likely to result in movement.
16.13.3 The knockout shall remain in place, and the clearance between the knockout and the opening
shall be no more than 1.6 mm (0.063 in) when measured after the force has been removed.