This part of IEC 60999 applies to screw-type and screwless-type clamping units for connecting devices, either as separate entities or as integral parts of equipment, for the connection of electrical copper conductors (complying with IEC 60228), rigid (solid or stranded) and/or flexible, having a cross-sectional area of 0,2 mm² up to and including 35 mm² and equivalent AWG sizes with a rated voltage not exceeding 1 000 V a.c. with a frequency up to and including 1 000 Hz, and 1 500 V d.c. It applies to clamping units primarily suitable for connecting unprepared conductors. This standard does not apply to clamping units a) for connection by crimping or soldering; b) for data and signalling circuits; c) for flat quick-connect terminations, insulation-piercing connecting devices and twist-on connecting devices, which are covered by IEC 61210 [3]1), IEC 60998-2-3 [1] and IEC 60998-2-4 [2] respectively.