This International Standard specifies outside diameters for conduits used in electrical installations or in communication systems and the dimensional requirements for threads. It also specifies the dimensional requirements for threads used in associated fittings. It is not applicable to extra heavy-duty electrical rigid steel conduits specified in IEC 60981. This third edition cancels and replaces the second edition published in 1993. This edition constitutes a technical revision. The following main changes have been made to the second edition: -revised figures and tables plus editorial and normative reference updates -conduit range increased to 110 mm outside diameter.