GB2192761A - Wiring accessory cable clamp and terminals - Google Patents

Abstract

A wiring accessory in the form of a ceiling rose 1 includes, (a) a cable clamp (Fig. 2) in the form of a snout in two hermaphroditic pieces which are pivotally mounted near apertures 7 in the rose 1 and clip together so as to clamp cables in snout clamps 27, and (b) contacts (Fig. 6) each having jaws which grip a wire when the contact is press fitted in an appropriate recess in the rose. The terminals are preformed in a strip having a plurality of frangible break points so as to make up blocks of contacts for earth E (Fig. 1), line L, neutral N and switch S from a single contact strip. (Fig. 7 not shown). <IMAGE>

Description

SPECIFICATION Electrical accessory wiring connection The present invention relates to an electrical accessory wiring connection such as in a ceiling rose, junction box or the like for electrical mains connections, and is being developed particularly in relation to ceiling rose affording loop-in facilities.

A known loop-in ceiling rose uses a moulded plastics base or back plate having three sets of screw connection terminals in respective connector blocks disposed in-line, and has been found to be convenient in use, particularly in wiring up. Like other known ceiling roses such back-plate has fixing holes for securing by screws to a ceiling or box, and has knock-outs through which wires within cable sheathing are passed to introduce them into the ceiling rose for stripping back and connecting the conductors with screw connection terminals to establish electrical connection. A cover is fitted over the base and, of course, the wires where they emerge from cable sheathing. The cover is usually a screwfit on the base and is provided with a hole for passage therethrough of a lighting drop cord leading to a lamp-holder.

The fitting of such a ceiling rose or other ceiling roses direct to a ceiling requires removal of one or more base knock-outs, and supply cabling to be passed there-through from a hole in the ceiling. Usually, or at least at rewiring the ceiling rose base will be fixed to the ceiling, with the hole in the ceiling communicating with at least one of the knockouts, before making electrical connections, i.e.

stripping back cable insulation and clearing insulation from ends of the wires for connection to appropriate terminals.

With the known ceiling roses the electrician has to make screw connections at or close to the ceiling, often from a ladder, which can be awkward and time-consuming. Accordingly, an arrangement which is simpler and quicker to wire up is desirable.

A further factor is that lighting cable should enter the ceiling rose and protrude to some extent with its outer sheath intact even after stripping back for access to its wires. Known ceiling roses offer no aid to- doing so or otherwise assuring that the sheathed cable is within further insulation at entry, a'there is little space within such ceiling roses to encourage doing so. At least amateur wiring-in may well result in cable outer sheathing being stripped back right to knock-out entry, possibly even further. This situation is, of course, exacerbated where loop-in wiring techniques are employed, when three twin-and-earth cables have to be introduced into the ceiling rose for connection of their nine wires to terminals within the confines of the ceiling rose.

The present invention aims to provide an improved mains electrical accessory wiring connection which overcomes the aforementioned difficulties and simplifies the wiring-in procedure, and there are two main aspects of this invention contributing thereto.

According to one aspect of the present invention there is provided a mains electrical wiring connection accessory comprising a housing accommodating plural terminal connection provisions with access thereto for at least conductor wires of mains cable or cables through aperturing of said housing, the housing having means extending externally thereof and shielding said cable or cables, which means may serve also to grip said cable or cables and at least then may be as a part or parts connectable with said housing adjacent said aperturing.

For the last-mentioned means to grip on the basic insulation, but preferably on the cable outer sheathing, at least one of its parts is advantageously movable relative to the other in or on the housing area. In fact, another aspect of this invention can be viewed as providing for such cable gripping irrespective of (though preferably with) shielding, say as spaced extending arms or a skeletal extension from the housing.

Preferred means shielding the cables presents a tubular, conical or tapered snout adapted to fit around all the cables feeding into the terminal provisions and provided with means for connecting it to the housing at least when the cables are in position. More especially, the shield and/or gripping means may comprise two members, which are movably mounted relative to one another and advantageously mounted on the housing for pivotal movement. The members are movable between an open position to permit the conductor wires to be fitted into the terminal provisions, and a closed position when the cables are shielded and/or gripped. The two members are preferably identically constructed in such a way that when mounted face to face they are interengageable, at least in the closed position.Each member may have a hooked arm and indentions, the hooked arm of one member being co-operable with the indentions of the other member in the closed position.

Other closure locating means may be employed.

It is preferred that the two members define a snout having a wide base adjacent said apertures to the terminal provisions, and converging to a narrow cable entry. More especially the cable entry is provided with barbs for engaging grippingly the cable when the members are in their closed positions.

The above shielding aspect of this invention is capable of fully meeting requirements to cover a short length of intact outer cable sheathing, and to do so without such outer sheathing having to enter the accessory housing where the electrical connection terminal provisions are located.

The terminal provisions could be screw-type terminals but are more preferably of push-fitting action comprising for each conductor a resilient conductive clip, say of C-shape having contact-making portions adjacent its mouth of the terminal and urged together resiliently.

More especially, each said terminal can have its limbs bent towards each other and then away to form said contact portion, effectively defining a tapered mouth to facilitate receiving the end of the conductor for making the electrical connection.

The other main aspect of this invention intimated above concerns push-action electrical connection provisions, especially for easy push-fitting of bared conductor wires ends between contact-making limbs without requirement for tools to open the latter, in conjunction with gripping applied at a spaced position, especially to the outer-cable sheath via the aforementioned shielding and/or gripping means.

One especially advantageous application of such electrical accessory wiring connection is in a ceiling rose. Then, the electrical connection provisions can face rearwardly of the base or back-plate for entry of conductor wire ends through the aforesaid shielding/gripping means extending rearwardly from said base, preferably for simple emplacement in a hole through a ceiling. It is then preferred that the base afford two fixing positions to one side of such rearward extension for fixing to a joist adjacent said hole.

A ceiling rose of loop-in type has to accommodate up tb three twin-and-earth mains supply cables (as well as two cores of a cord for wiring in the lamp drop). It is proposed to provide plural sets of terminal provisions for the ceiling rose, conveniently mainly side-byside in a compact array, and each preferably of the aforesaid push-fit type. Then, access to said terminal provision is by way of respective ones of an array of holes in the housing one for each of the nine terminals, said array being below said rearwardly extending shielding and gripping means.

We prefer to form wells in the housing base say on the side remote from the rear face into which blocks for the terminal sets are placed and captured by retention means, such as a cover secured therefor. We prefer to mould the housing from a plastics material and to make the 'retention means in the form of a plastics plate which should be sedured in place and- can be welded.

It is convenient to make the 'terminals in strip form which can be cut into the desired configuration of terminal groupings for earth, neutrai, live and switched returns. The terminais are effectively on a carrier and can be arranged in groups of three on the carrier and with a length of carrier between the groups then, terminal groupings of one, two and three terminals with a projecting carrier strip can be produced as well as three terminals without a projecting carrier strip. The projecting carrier strip allows for fitting of a screw clamp, even crimping terminal connection of any desired type as may be required for each of the neutral, earth and switched return of a ceiling rose. The latter terminal connections can, of course, be readily accessible from the inner face (room side) of the base.For such a desired ceiling rose, preferred mating shield/grip parts have ribs defining accommodations in the cable entry for three cables.

Of course, suitable push-in terminals and cable shield/grip means could be employed with other electrical accessory wiring connections, for example junction boxes, where the number of terminal provisions may be increased or decreased, but preferably using terminals in groupings of three, whether with or without the projecting carrier and additional screw terminal connections.

Preferred implementation of the present invention will now be described further, by way of example, with reference to the accompanying drawings; in which: Figure 1 is a plan view of the inner face of a base or back-plate of a ceiling rose with terminals omitted; Figure 2 is a section on line ll-ll of Figure 1; Figure 3 is an end view of a cable sheath/gripper component of Figure 1; Figure 4 is a section on line IV-IV of Figure 3; Figure 5 is a side elevation of a terminal set for use in the illustrated ceiling rose; Figure 6 is an end view of a terminal or set; and Figure 7 is an elevation showing the repeat length of a strip of terminals.

In the drawings, base or back-plate 1 of a ceiling rose is shown in Figures 1 and 2. It is conveniently moulded from plastics and circular in outline as shown. It is provided with countersunk holes 3 at least two of which may be used with fixing provisions, such as screws, to secure the ceiling rose to a ceiling, if convenient.

A plurality of terminals are to be received in a terminal housing 5 moulded into the base plate and comprising wells L, N, E and S for respective live, neutral, earth and switch return terminal groupings. (Figure 1 shows the inner side of the box plate with the terminals and the retention means therefore omitted.) Visible are respective apertures 7 in the base walls of the wells, see also Figure 2 showing extension from the rear face of the base and convenient flared entry parts 9. Nine apertures 7 are shown in the illustration and these provide entry provisions for respective mains conductor wires (not shown) when stripped of insulation at least beyond the apertures 7. The mains conductors are a push fit into terminals T, (Figure 6), access thereto being by way of said entry provisions.

The terminals T are each in the form of a resilient clip-say of C-shape, with the mouth thereof closed by the resilience of opposite limbs 11 which are bent at the ends to form contact portions 0 and a diverging mouth M so that the limbs part for entry of conductors pushed theretowards. Figure 5 of the drawings shows a side view of a three-terminal set which also shows an end extension.

The terminals T are conveniently formed by folding up from a carrier strip 13 of conductive material, see Figures 5, 6 and 7. Figure 5 actually shows the terminal set for receiving earth wires, in which three terminals T have an end extension of carrier 13. This grouping is fitted into the well T with the mouths M of the terminals opposite the apertures 7. Fixed to the extended end of the carrier 13 will be a normal screw type terminal block (not illustrated).

Figure 7 shows one repeat length of a strip of terminals T bent from common carrier 13.

The terminals T are in regular groups of three and for the illustrated ceiling rose three groups of-three in a strip can be further cut to provide the necessary four terminal sets L, S, N and E, from left to right as illustrated by cutting the carrier at A, B, C and D as indicated.

All but the live set L have a projecting strip of carrier to which a respective screw type terminal block is fitted, one as mentioned above for general earthing purposes, and the others for lamp drop cord cores. These terminal sets are received in the wells of the terminal housing 5 as described in the example of the earth group. A retention plate 15, conviently welded in place, serves to retain the terminals sets in position in the respective wells.

A cover (not illustrated) is readily fitted over the base to conceal the respective terminal blocks and wires thereto, with the cover having a hole through which the lamp drop cord passes from the said terminals to the lampholder. There will normally be a grip for said cord between the terminal blocks and the cover, say fixed to the base Providing the mains conductors as a push fit in the terminals T enables the connections to be made especially quickiy, and even more donvenient is the fact that they are accessible from the ceiling side of the ceiling rose.

Using loop-in wiring, three twin-and-earth cables have to be fitted into the terminals T, hence the provision of nine terminals, one for each wire. With the immediate wire insulation stripped back from the individual conductors and the cable sheathing stripped back to allow spreading of the individual conductors, an insulating enclosure about the cables is provided to meet wiring regulations.

This is achieved by a snout-like extension from the rear face of the ceiling rose base so as to extend upto and past the point to which the cable sheathing is stripped back, see Figure 2. The snout extension can usefully serve to grip the cables to retain them in the terminals T. Thus, the sheath/grip comprises two identical components 19, only one shown in the illustrations, which are mounted back to back and arranged for movement relative to one another for which purpose they are pivotally mounted on the rear face of the base plate 1. Oppositely disposed lugs 21 with a respective hole 23 are provided for cooperating engagement with a respective pivot point on the base plate. The parts 19 can thus be pivoted towards and away from one another between closed and open positions. In the open position, the conductors can be pushed into the terminals T.The parts 19 are shaped to define a conical snout, with a wide base diverging to a narrow entry having ribs 25 defining three cable entry ports 27, each to receive a respecive mains cable. Teeth 29 in the form of inclined barbs are provided for gripping the cables to prevent them being withdrawn accidently. To hold the components 19 in the closed position a hooked limb 31 is provided and adapted to cooperate with one of several indentations 33 in the corresponding part 19. By pushing the conductors into the appropriate terminals, and closing the sheath/grip components, the cables are securely held in position.

It will be understood that the concept of rear entry and/or push fitting for wiring up mains electrical accessories can take other forms to that illustrated and described above.

The use of push connections and a combined cable grip/sheath can be employed for a junction box, in which case the screw terminal provisions can be omitted, and of course, the housing for the terminals may be mounted the opposite way round to allow access to the entry provisions.

Of course, the convenience of rear entry may be employed with screw type terminals, in which case, a clip on sheath need only provide sheathing functions-omitting the gripping teeth. The sleeve may be a separate component, even one piece, first slipped onto the wire before wiring in, and then fitted onto the base plate-say as a push fit. More preferably, the aforedescribed two part pivotable arrangement may be employed. Of course, the cable gripping may be used as an additional security measure. The use of a snout is advantageous and can minimise the material required for the base plate.

In certain circumstances it may be desirable and advantageous to arrange for the push terminals to incorporate gripping teeth to resist pulling out of the conductors, or for some other aid to be provided for assuring grip, e.g.

holding/clipping terminals mouths. Of course, following on from the requirements to meet anti-fire regulations, it is envisaged that the aforedescribed sheaths could be employed with base plates having rear entry provisions for wires, knockouts or otherwise, to lead into the ceiling rose for connection with terminals on the room side, probably of screw type.

Such an arrangement would allow the cable sheath to be stripped back for individual conductors with immediate insulation to be passed through the knock-out and thereafter the sheath closed up or fitted in position about said rear entry provisions to cover said immediate insulation back to the cable sheathing. It will be understood that the bending of such conductors and the space requirements within the ceiling rose or other such box is considerably easier if the cable sheathing is removed.

The number of terminals accommodated in the mains electrical accessory may be increased or decreased to meet individual requirements.

Claims (31)

1. A mains electrical wiring connection accessory comprising a housing accommodating plural terminal connection provisions with access thereto for at least conductor wires of mains cable-or cables through aperturing of said housing, the housing having means extending externally thereof and shielding said cable or cables and/or serving to grip said cable or cables.

2. A mains electrical wiring connection accessory as claimed in claim 1 in which said means is at least as a part or parts connectable with said housing adjacent said aperturing.

3. An accessory as claimed in claim 1 or 2 in which said means grip directly on the basic insulation of the conductor wires or indirectly by way of the cable outer sheathing.

4. An accessory as claimed in claim 3 in which gripping of said means or said insulation/sheathing is by having at least one of its parts movable relative to the other in or on the housing area.

5. An accessory as claimed in any one of claims 1 to 4 in which said means comprises spaced extending arms from the housing.

6. An accessory as claimed in any one of claims 1 to 4 in which said means provides sheathing for said cable or cables extending from said housing.

7. An accessory as claimed in claim 6 in which means shielding the cable(s) presents a tubular conical or tapered snout adapted to fit around all the cables feeding into the terminal provisions.

8. An accessory as claimed in claim 6 in which said shielding means is provided with means for connecting it to the housing at least when the cables are in position.

9. An accessory as claimed in any of claims 6, 7 or 8 in which said gripping and/or shielding means comprises two members, which are movably mounted relative to one another with at least one mounted on the housing for pivotal movement.

10. An accessory as claimed in claim 9 in which the members are movable between an open position allowing the conductor wires to be fitted into the terminal provisions, and a closed position when the cables are shielded and/or gripped.

11. An accessory as claimed in claim 9 or 10 in which the two members are of identical construction so that when mounted face to face they are inter-engageable, at least in the closed position.

12. An accessory as claimed in claim 11 in which each member has a hooked arm and indentions, such that the hooked arm of one member is cooperable with the identions of the other member at least in the closed position.

13. An accessory as claimed in any one of claims 9 to 12 in which the two members define a snout having a wide base adjacent said aperturing to the terminal provisions, and conveying to a narrow cable entry.

14. An accessory as claimed in claim 13 in which the cable entry has barbs or other rib formations for engaging grippingly the cable when the members are in their closed positions.

15. An accessory as claimed in any one of the preceding claims in which the terminal provisions have a push fitting action.

16. An accessory as claimed in claim i5 in which the terminal provisions for a conductor comprise a resilient conductive clip, of say Cshape, having contact-making portions adjacent its mouth of the terminal and urged together resiliently.

17. An accessory as claimed in claim i6 in which each said terminals have limbs bent towards each other and then away to form said contact position for electrical contact with bared ends of said conductor wire.

18. An accessory as claimed in any one of the preceding claims in which the electrical connection provisions face rearwardly of the base or back plate for entry of conductor wire ends through the aforedescribed shielding/gripping means extending rearwardly from said base.

19. An accessory as claimed in claim 18 having plural sets of terminal provisions.

20. An accessory as claimed in claim 19 in which said plural sets of terminal provisions are disposed side by side in a compact array.

21. An accessory as claimed in claim 20 in which access to said terminal provisions is by way of respective ones of an array of holes in housing means for the the terminal provision.

22. An accessory as claimed in claim 20 or 21 in which the array comprises nine connections in a matrix 3 x 3.

23. An accessory as claimed in claim 20, 21 or 22 in which said array is below said rearwardly extending shielding and gripping means.

24. An accessory as claimed in claim 21, 22 or 23 in which wells are formed in the housing base, into which blocks for the terminal sets are placed and captured by retention means.

25. An accessory as claimed in claim 24 in which said wells are formed on the side remote from the rear face.

26. An accessory as claimed in claim 24 or 25 when made from a plastics material and the retention means is in the form of a plastics plate secured in place by welding.

27. An accessory as claimed in any one of the preceding claims in which terminals of the terminal connection provisions are made in strip form and cut into the desired configuration of terminal groupings.

28. An accessory as claimed in claim 27 in which the strip form of the terminals comprises a carrier with terminals in groups of three and with a length of carrier between the groups so permitting cutting into the desired configuration of one, two and three terminals with a projecting carrier strip and three terminals without a projecting carrier strip.

29. An accessory as claimed in claim 28 in which the projecting carrier strip serves to allow fitting of a screw clamp terminal.

30. An accessory as claimed in any one of the preceding claims when configured as a ceiling rose.

31. A mains electrical wiring connection accessory constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.