Abstract: The invention concerns twist on wire connectors for electrically connecting ends of wires. A cap is provided in combination with an expansion spring for gripping the wires, the cap having thin walls and external ribs providing the walls with rigidity and a gripping surface. Within the cap is a hollowed out region to allow the spring space to expand. Preferably the spring is of slightly concave shape in an axial direction i.e. it is waisted. The new connector caps permit the economic use of expansion springs and permit a greater range of wire sizes and number of wires to be gripped by a connector.

Abstract: A twist on electrical connector is provided, comprising a moulded thermoplastic cap and a wire coil insert therefore. The cap is a thin walled structure, and the coil is in substantially intimate contact along its entire length within the innermost, wire retaining portion, of the cap. A plurality of radially extending ribs, having substantial height and width, is formed on the outer periphery of the cap, at least in the upper portion thereof. The outwardly extending ribs provide a better finger grip, and are generally spaced apart such that the distance between any two adjacent ribs is below the 2-point threshold of discrimination for a human finger. The ribs permit better heat dissipation from the interior of the cap, in the event of heat build up therein; and the generally thin walled construction permits easy injection moulding techniques with relatively quick mould cycle times.