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.