IEC 60884-1-2013 clause 9.2
These weights are intended to verify and checking the impossibility of insertion to sockets-outlets.
Socket-outlets for household and similar purposes.
Cylinder weighs. Use the weights to applying the appropriate gauge with a force of 150 N for 1 min for accessories with a rated current not exceeding 16 A, or 250 N for other accessories, checking the impossibility of insertion of socket-outlets.