Applicable 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, rigid and/or flexible, having a cross-sectional area of 0,2 mm[2] up to and including 35 mm[2] and equivalent AWG sizes with a rated voltage not exceeding 1000 V a.c. with a frequency up to and including 1000 Hz and 1500 V d.c.