GB969735A - Electrical cable connections and junctions and methods of making the same - Google Patents

Abstract

969,735. Cable terminations. SOC. ANON. DE TELE-COMMUNICATIONS. May 13, 1963 [June 14,1962], No. 18766/63. Heading H2E. A sealed end connector for a cable having a non-metallic protective sheathing comprises one or more circumferential rings bonded to the sheathing, a concentric metal collar surrounding said rings and forming a cup in which they are contained, and sealing material filling the collar and bonding the interior of the cup to the rings. As shown, a telephone cable 2 comprising polyethylene insulated conductors 9 protected by inner polyethylene sheath 8, helically disposed metal strips 7 and by outer polyethylene sheath, has brass collars 13, 14 brazed to a sleeve 12 which is taped on to the outer sheath and has its outside surface which penetrates inside the member 14 sanded. The sealing material used is a mixture of an epoxy resin and curing agent and is poured into the cup 14 and since epoxy resins do not stick to polyethylene the rings 1 of metal tape, e.g. copper or aluminium about 0.07 mm. thick, coated on one side with polyethylene or tapes of glass or cotton cloth are first bonded to the polyethylene cable sheaths by a soldering iron (Fig. 2, not shown) or a hot-air torch (Fig. 3, not shown). When positioned, the tapes are roughened and degreased. The glass or cotton cloth tapes may be embedded in the cable sheath which is softened by using a flame torch. Electrical continuity between conductor strips 7 on either side of the joint is ensured by means of wire 10 insulated by vinyl chloride. Since the volume of epoxy resins decreases slightly during polymerization, a cardboard or plastic packing 17 is is placed round the inside surface of the collar 14 so that the resin does not stick to this surface and thus shrinks towards the axis of the cable forming a better seal. The sealing material also penetrates into the cable core and forms a sealing plug which prevents any water from entering the joint in the event of the two protection sheaths being pierced. After the conductor wires of two cables ends have been intercomnected a lead sheath 18 is slid on to the two outer collars 13 and welded or soldered into place to complete the sealed joint. Before the joint is made the collar assembly is given a leakage test (Fig. 4, not shown). As shown in Fig. 5, similar cable ends may be used in a junction-box 27 in which tubes 31 are nipples through which the sealing mixture can be poured, the open end of each collar being closed by a split rubber washer 33, the junction-box having removable cover and four entries which are later soldered together.