This standard applies to connecting devices with insulation piercing clamping units primarily suitable for connecting insulated unprepared conductors. In the connecting operation the insulation of the conductor is pierced, bored through, cut through, removed, displaced or made ineffective in some other manner at the point or points of contact. This Part 2-1 is intended to be used in conjunction with IEC 60998-1. It was established on the basis of the second edition (2002) of that standard. This second edition cancels and replaces the first edition published in 1991 and constitutes a technical revision. The contents of the corrigendum of November 2006 have been included in this copy.