This standard is applicable to locking devices used with ball and socket couplings of string insulator units and used with the corresponding metal fittings standardized in IEC 60120, when they are supplied separately. When these locking devices are supplied with an insulator or fitting, they shall be considered as an integral part of it. In this case, the relevant test shall be included with those of insulators, as specified in IEC 60383-1 and IEC 61325. On request, a certificate shall be delivered confirming that the tests on locking devices as specified in this standard have been carried out. The locking devices are usually supplied with the insulator or corresponding metal fittings. The object of this standard is " to define the shapes and some standard dimensions for locking devices, " to define the test methods for locking devices, " to state the acceptance conditions for supply, " to give other dimensions for guidance of manufacturing only. The object of this standard does not include the specification of the nature of the material, but it is recommended that this material does not have a surface coating for corrosion protection. Moreover, the material shall not give rise to significant contact corrosion (chemical reaction) between the locking device and the ball and socket coupling.