Deals with screw-type and screwless type clamping units for connecting devices, as either essential parts of equipment or as separate entities, for connecting of electrical copper conductors (which comply with IEC 60228), rigid (stranded or solid) and flexible, with cross-sectional area of 0,2 mm[2] to 35 mm[2] and equivalent AWG sizes having rated voltages up to 1 000 V a.c. and frequencies not exceeding 1 000 Hz, and 1 500 V d.c.