Patent GB-1259493-A (GB)
IPC: H01R25/16
Filed: 1969-02-28
Abstract: 1,259,493. Conduits; electric couplings. LA TELEMECANIQUE ELECTRIQUE. 28 Feb., 1969 [12 March, 1968], No. 10972/69. Headings H2C and H2E. An electrical distribution system comprises rigid tubular conduit lengths A (Fig. 1) connected end-to-end by channel-shaped link members 27. Each conduit length A has a laterally offset keyhole aperture 25 at each end. Correspondingly offset tapped holes in the link members receive screws 26, 26a which cooperate with apertures 25 and so ensure that the link members and the conduit lengths can be secured together only when in correct alignment, thus polarizing connections between supply conductors 1. Each link member 27 has lugs 28 which engage portions 25b of the apertures 25. Electrical connection of the supply conductors 1 is effected by a device 35, which comprises a moulded insulator 36 containing U-section conductors to which the ends 5 of the supply conductors 1 are clamped by screws 40. An integral insulating lining in a lid 33 prevents shorting of the screws 40 by the lid. Similarly, insulating sheaths surround the lid securing screws 32. The end of a line of conduit lengths may be closed by a flat plate. Current may be tapped from the system through apertures 7 in closure strips 3 of the conduits. Bared portions 6 of the conductors engage grooves 8 (Fig. 7) in half-bearings 9, which are coupled by means of co-operating dowels 11 and recesses 12. The coupled bearings accommodate a hollow cylindrical component 15 which receives through the aperture 7 a tapping connector (not shown), notches 18, 19 on the opening 7 ensuring that this con- . nector can only be introduced in one orientation. Similarly, lugs 20, 21, on component 15 ensure that it can be rotated only in the direction to achieve correct polarity. The component 15 is provided with resilient lugs 20 having cavities 22 engaging bosses 23 1 , 23 2  or 23 3 , which define positions which allow the connector to be introduced, be locked in position without making contact, and make contact respectively. A current lead-in cable is connected to the system through a support (55, Fig. 8, not shown) in the conduit end, a marked T-plate with offset apertures indicating the correct connections. A terminal (74) facilitates earthing of metallic parts, and the neutral conductor may be earthed via a bent conductor (75). A knee section (Fig. 10, not shown) enables two conduits to be connected at right angles and comprises a channel (77) in which is located a pivoted L-shaped shutter (79) one arm of which has a central aperture and the other has two symmetrically placed apertures. The channel includes a pair of apertures in each arm, symmetrically disposed on either side of a plane of symmetry, and consequently the shutter can be secured in one of two positions corresponding to either end of a conduit length. To effect electrical connection at a knee section, four conductors, each bent into a right angle and located in two angled and joined connector shells, are employed (Figs. 12, 13, not shown), this whole assembly being located in the knee by resilient press-studs. In a cross-link (Fig. 11, not shown), four such insulating shells are used to house interconnected pairs of conductors (Fig. 14, not shown). The pairs of conductors are bent so that only desired pairs make contact. The cross-link permits crossing of conduit lengths, a departure to either side, or a T-bifurcation at the end of a conduit. If a leg is not in use, an insulator having separate boxes for the reception of each conductor is used for closure of the arm of the cross.