Electrical contact system of the insulation displacement type

An insulation displacement contact 12, 14 is formed in a plate 10 with a slot 28 having a wider 32 and a narrower 34 portion. The plate is received in a longitudinal slot 42 in a moulding 40 which has transverse slots 46, 48 of different depths having bars 50, 52 in line with the contact slots 28. The higher bar 50 receives a thinner conductor 60 and forces in into the narrower part 34 of the slot 28. The lower bar 52 receives a thicker conductor 62 and pushes it into the wider part 32. Thus the identical contacts 12, 14 can accommodate wires of different diameters. The different heights can alternatively be provided by the use of inserts or break-off sections of the moulding. In another embodiment (Figure 7), the contact is slidable into a sleeve which has a pair of aligned large apertures and a pair of aligned small apertures in its walls. The slot can receive a thinner and a thicker conductor simultaneously. In a further embodiment (Figure 10) a cap serves to push the conductor into the slot and has several detent positions so that the user can feel when the position appropriate to the diameter of the wire used is reached.