GB2245427A - Electrical switch accessories - Google Patents

Abstract

A demountable tell tale unit 90, eg a noon, is engageable with the terminals of an electrical switch accessory accessible from the front or top of the accessory so as to indicate whether or not a local circuit is receiving current, and has external terminals 92A, 92B by which it is energised from the terminals. In a switch having plural operating rockers. one of the terminal blocks with its associated stationary contact may be replaced by a dummy insert to avoid removing a switch operating plunger associated with a rocker. An electrical accessory may be mounted in a wall box (Figs 9-11) or on a mounting rail by means of pivotable U shaped members (Fig 3). Reference is made to an electrical accessory in the form of an electrical socket or spur connection. <IMAGE>

Description

ELECTRICAL ACCESSORIES This invention relates to electrical accessories intended for use in mains distribution systems and has particular reference to features of switches and their assembly for various particular applications.

Use of mounting rails, including those of DIN type (though not necessarily of outwardly flanged inverted-top-hat section), is, of course, already known, particularly in so-called consumer units where fuse-ways and/or circuit breaker units are supported side by side on such rails. Application of similar mounting rail techniques is readily extended to so-called grid switch provisions where each rail follows one extent of the grid, conveniently a row, i.e. again serving plural individual accessories side-by-side at a distribution position or switch centre.

In related developments, see also our copending European applications No 91303434.4 and (co-filed), we have established a mounting rail philosophy applicable both to busbar-in-trunking with accessory-receiving flange formations above the busbar and to accessory boxes with inserts affording accessory-receiving flange formations and ease of wiring access within the boxes, which are preferably of generally conventional overall size and shape to what is presently used for mounting plate type electrical accessories. It is preferred for the inserts to be fixed using normal screw-in provisions of such boxes relative to conventional accessory plates.

Such accessory boxes are well suited to mounting one or more modular switch units side by side in a number limited only by the extent of the mounting rail, such extent itself being dictated by clearance requirements and dimensions of the box, particularly the width between its plate attachment provisions, or normal positions therefor.

Various aspects of invention arise, not all limited to application for switch units. One such aspect concerns an electrical accessory having accessibility of connection making means from the front or top of the accessory, and comprises provision of a mountable or demountable tell-tale unit, such as a neon light, for indicating whether or not a local circuit served by the accessory is receiving current, i.e. is in an "on" state, for a switch or switched accessory.

Accordingly, a tell-tale device responsive to electrical power being taken off through an associated accessory comprises a self-contained unit having external contact means by which it is energised, and the associated accessory and the tell-tale unit have mutually cooperating parts whereby, at least in the assembled state of the accessory, the external contact means of the tell-tale unit is maintained in position in contact with electrical connection making means of the associated accessory, preferably directly in order to save providing specific conducting extension from such latter means.

As applied to a switch or other switched accessory with access to its connection making provisions from its front, it is further preferred that the tell-tale unit cooperate for locating purposes with parts of the accessory exposed on removal of its front cover, even, and advantageously, simply a cover of a switch member for a rocker type switch.

Advantageously, a separable rocker cover has an opening, typically a slot, capable of receiving a decorative or labelled strip or a lens for a neon type tell-tale.

Preferred electrical switch accessories have aspects including a lower body part formed and partitioned to accommodate two sets of one-way switch contacts side by side and separated by a said partition so that functions other than one-way switching require connections between stationary contacts of the two sets and mechanical ganging of the moving contacts of the two sets for operation together. T h i s a spect i s extendable to easy manufacture of an accessory where its lower body part has other components installed progressively to either side of its partition, i.e. with similar accessory provisions and functions are provided in each of compartments to each side of such partition.

For electrical switches making simplest provision in each compartment, namely single-pole one-way switching relative to two mains input terminals conveniently at each end of elongate narrow such compartments, other functions can be achieved by internal and/or external connection, including double-pole and/or two-way and/or relay operation, for two adjacent compartments having their switch operating means ganged together, such as a single rocker cover.

Other aspects include such lower body parts permitting mains supply wire entries through their ends, affording access to mains wiring connections from the front of the accessory, say requiring only removal of cover means and/or a switch rocker cover, and application of alternative plates to single or multiple accessory units hereof.

Specific implementation for this invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures lA-iC constitute an exploded view showing practical latch members 10,10', for an electrical accessory body part 20, initially for a switch having other parts going into or onto said body; Figures 2A-2C show the parts of Figures lA-iC assembled together, respectively; Figure 3 shows the assembled switch; Figure 4 is a part-long section of an accessory fitted with a neon tell-tale unit; Figure 5 is a corresponding end-view; Figures 6A,B and C are plan, side and end views of the neon tell-tale unit; Figure 7A,B, and C are plan, side and end views of a rocker counterbalance insert;; Figures 8A-F indicate variant accessory module fittings relative to equivalent of one standard size of accessory plate; Figures 9A and B are sections showing variant cover frame thickness and fitting thereof to an accessory box; Figures 10A and B are plan and end views of an accessory holding part of an accessory box including insert; and Figures llA and B are plan and section views showing locating formations of an accessory lower body part.

In the drawings, latch members 10,10' are of generally U-configuration with limbs llA,B stepped inwardly (12A,B) at their free ends to provide lower semi-cylindrical surfaces 13A,B and upwardly directed inset lugs 14A,B. Limbs llA,B also carry inwardly projecting latching edges 15A,B. Bight portions of the latch members have outward extensions 16 of generally Uconfiguration presenting an aperture 17 and an bight 18A,B, and inward extensions 19A,B. The bights 18A,B are shown upstanding but could be otherwise, including inclined downwardly.

Lower body part 20 of the electrical accessory, specifically switch unit, is shown of dished configuration, actually open-topped box-shape with upstanding outwardly diverging side walls 21A,B and end walls 22A,B. The side walls 21A,B are shown with slots 23A,B (and 23A',B') from their outset upper rims 24A,B to semi-circular surfaces 25A,B in which the semicylindrical surfaces 13A,B will bear for pivotting of the latch members 10,10' relative to the body part 20 with the teeth 14A,B inside the rims 24A,B. The side walls 21A,B further have lower recesses 26A,B, shown as holes directly below the slots 23A,B beyond indents 27A,B and retaining rib formations 28A,B.

The latch members 10,10' can pivot into and-out of their engagement positions with studs 15A,B in recesses 26A,B and involving passing over ribs 28A,B.

The engaged position is shown for latching member 10' in Figures 2A and 3, and the disengaged position for the latching member 10. A tool, such as a screw driver blade in holes 17,17' can be used to get at least disengagement after engagement. Engagement will actually be relative to flange formations under which the projections 19,19' will pass, preferably with at least resilient grip, if not latching, on undersides of the flange formations.

Retention of the latching members 10 and 10' in the slots 23A,B and 23A',B' is assured by an upper body part 30 of the electrical accessory, specifically switch, for which the upper body part 30 comprises a plate 31 fitting inside the rims 24A,B of the side walls 21A,B and further rims 29A,B for the end walls 22A,B of the lower body part, with lugs 32A,B and 32A',B' going into the rim slots. Snap-fitting of the upper body part 30 to the lower body part 20 is shown by way of chamfered teeth 33A,B of the latter and chamfered bights of external depending U-formations 34A,B of the former.

(Not all of subscript 'B' items are shown, but are specified for the sake of indicating completeness of correspondence of parts.) It will be appreciated that first and second accessory body parts may fit together differently, for example permanently or semi-permanently glued or welded.

Also, the particular electrical accessory concerned is immaterial, and could just as well be an electrical socket or a spur connection or whatever.

As a switch unit, however, the particular accessory shown is advantageous in its own right, whether as to its longitudinally divided nature, see interrupted partition 40A,B, or as to other features also now to be described.

To each side of the longitudinal partition and at one end of the compartments so formed are terminal blocks 41A,B shown of screw-clamp type for wires entrant end-holes 42A,B in lower body part ends 22A,B and holes 43A,B of the blocks 41A,B. Clamp screws 44A,B are accessible through holes 45A,B in the upper body part plate 31, actually shown within upstanding necks 46A,B.

The terminal blocks 41A,B have extending from their bottoms conducting spring plates 47A,B having reduced width and downwardly V-formed parts 48A,B, and fullwidth free edges 50A,B fitting in slotted cross partitions 49A,B and 49A',B'.

At their other ends, the compartments flanking the partition 40 have terminal blocks 51A,B generally similar to those 41A,B and with similar related means referenced 52-56A,B. From tops of the terminal blocks 51A,B, conducting spring plates 57A,B extend with offset downwards and sideways extensions 58A,B to fixed contacts 59A,B each in the other compartment and resting on the bottom of the lower body part 20. Sideways extensions 58A,B are protected by slotted insulating cross partitioning 60A,B and 61.

Rocking conducting spring plates 62A,B use free edges 50A,B of the contacts 47A,B as fulcrums at downwardly U-bent parts thereof with lowermost extensions to fit between the partitions 49A,A' and 49B,B', beyond which extend free edges 63A,B and actual contacts 64A,B capable of rocking into and out of engagement with the fixed contacts 64A,B respectively from above. The plate 31 has depending insulating plates 65A,B to fit each side of the partition 40 and give insulating shielding for the terminal blocks 44A,B.

Arrangement of contacts 59A,B and 64A,B relative to terminal blocks 41A,B and 51A,B and compartments to each side of the partition 40 allow the illustrated switch unit to be used as a single intermediate type switch. Two-way switch action will use both of the terminal blocks 51A,B and only either one of the terminal blocks 41A,B for connections. Two one-way switches are available if the plates 57A,B go only downwards i.e. not also sideways, and independently if the moving contacts are separately operable.

Arrangements for all mains clamp screws to be accessible at tops of the accessory and/or for access of mains wires at ends is or are advantageous in themselves.

For a single intermediate switch unit, as actually illustrated, there will be common activation of the two moving contacts using a single rocker unit 70 effectively ganged spring plungers 71A,B. Rocking location is by way of snap-fitting triangular side projections 72A,B in sectoral apertures 73A,B in upstanding side walls 74A,B of the upper body part 30, aided by chamfers 75A,B and 76A,B respectively. The plate 31 is centrally apertured at 77 to accommodate the rocker plungers 71A,B.

A two-way switch for optionally one- or two-way use, as is common in the industry, could, of course, omit one of the terminal blocks 41A,B with its stationary contact plate 48A,B and the corresponding moving contact 62A,B, also the sideways extension 58B,A into its compartment from the terminal block 51B,A of the other compartment. Then, rather than omit the corresponding plunger 71A,B, but still to give much the same 'feel' to operation of the rocker unit 70, there is a feature or aspect hereof that has merit in itself, i.e. of much more general applicability than the specific switch being described.That feature or aspect concerns a rocker or counterbalancing member insertable into a switch compartment instead of one or more contact member to offer a surface substantially corresponding to a locus of movement of a rocker plunger tip in operating absent said one or more contact members, i.e. as though present. Figures 7A,B,C show such a member 100 having an elongated profiled upper surface 101 providing said locus, and on elongate flat bottom surface 102 to fit snugly in place of one of the stationary contacts 48A,B.

A hollow cuboid end part 103 enables fitting in place of the corresponding terminal block 41A,B, and a bottom peg 104 can assist location by mating with recessing (105A,B in Figure 14A) of the base of the lower body part 20 for the stationary contact on which the moving contact pivots.

For two independent one-way switches, two rocker members will be required, for example replacing the rocker member 70 by two narrower members with either of mutual capture formations permitting relative rotation in the rocking axis or common capture of a rotation permitting part which could be as simple as a pin. An alternative would be to use a modified upper body part with a central formation affording sectoral recesses to each side for opposing further triangular projections of the two narrower rocker members.

Another feature or aspect of switches hereof is that the actual hollow rocker head 80 is made separate from the rocker unit 70 and fits thereto, preferably as a snap- fit using cooperating chamfered teeth 79A,B and 81A,B of ends of the rocker unit and internal partitions 82A,B of the hollow head, respectively.

A particular feature or aspect applicable to hollow rocker heads hereof is provision for a lens or indicator or merely decorative insertion, see full width slot 83 and corresponding insert 84. Access to mains clamp screws is readily available simply by removing the rocker head.

A neon unit is shown in Figures 4 and 5 associated with terminal block screws under the rocker head or cover 80, which, as shown, will be for the terminal screws 54A,B. Such a neon unit is shown at 90 in Figures 4, 5 and 6. The unit 90 has a neon holder clip 91 with conical spring contacts 92A,B down to screw heads of terminal blocks 51 and an interference or snap fit location 93 to the neck 56, see also Figures 6A-C.

Snap-fit of the neon lens 84N is also shown by way of resilient bifurcations 88 which be outwardly end-toothed for cooperation with interior ribbings 86. Base 94 of the neon unit 90 is such as to secure that all connecting leads and resistor 96 are inboard, see additional lead clip 95, crimp or soldered joint 97, and lead retaining formations 95A,B.

A particularly useful way of mounting to an accessory box user an insert 162 of multipart construction having two end parts that may be identical and a base part that may push fit to the two end parts, advantageously at alternative positions along the end parts. Figures 9 and 10 shown one specific embodiment by way of preferred inverted U-shaped end parts 264 having alternative securement ribs 268 X, Y in each limb, and a base part 263 side-flanged at 267A,B and having paired end extensions 269A, B each with one extension shown end-toothed to snap-fittingly grip onto the securement ribs 268 X,Y. The purpose of such provisions is to enable installation onto accessory boxes of different depths, for which a minimum is indicated dashed on Fig. 9B and available by trimming the limbs of the end parts 264 at 264Z.For use of the same accessory, in this that of Figures 1 to 3, a thicker frame member 270F is shown for a preferred twopart accessory cover of which face plates 270P snap fit into rebating 270R of the frame member 270F. Clip-in legs 271B for teeth 272 will also be correspondingly longer than (271A) a minimum depth accessory cover as shown in Fig. 9A, for which its frame member rebating will produce in inner edge part 274 not thinner than upper flanging of the end parts 264 and cut out (274C) to accommodate same, see dashed in Figure 8A. A further advantageous feature for base parts of multipart accessory box inserts is side rail surface formations to mate for locating purpose with bottom formation of the accessory concerned. That is indicated as indenting at 275A, B on one rail for one central accessory body and at 276A,B and 277A,B for two accessory bodies on the other rail, the base part 283 being reversable in the end part 264 as to which rail is uppermost and the accessory bodies having mating proud formations 278A,B (Figs. 11A,B). For accessory boxes other than a square one as one of the standards in current UK practice, for example oblong or so-called double or even triple boxes, the base part 273 can be longer and have more accessory locating formations 275-277. Variant accessory positions and fixed plates are indicated in Figures 8A F for a square box and cover.

Claims (14)

1. In or for an electrical switch accessory having accessibility of electrical connection making means from the front or top of the accessory, a mountable and demountable tell-tale unit for engaging the local current said connection means when mounted and indicating whether or not said local circuit concerned is receiving current, the unit having external contact means by which it is energised from said local circuit connection making means.

2. Electrical switch accessory according to claim 1, wherein the accessory and the unit have mutually cooperating parts for maintaining the external contact means of the unit in direct contact with said local circuit connection making means.

3. Electrical switch accessory according to claim 2, wherein the external contact means of the unit includes conductor compression spring means for compression against said local circuit connection making means.

4. Electrical switch accessory according to any preceding claim, comprising a lower body part formed and partitioned to accommodate two sets of one-way switch contacts side by side and separated by a said partition so that functions other than one-way switching require connections between stationary contacts of the two sets and mechanical ganging of the moving contacts of the two sets for operation together.

5. Electrical switch accessory according to claim 4, wherein stationary electrical contacts of each said set are at opposite ends of the lower body part and accessible for electrical supply wires through those ends.

6. Electrical switch accessory according to claim 4 or claim 5, wherein stationary contacts of each of the sets and disposed at one end of the lower body part have interconnections internally of the lower body part for at least one position of the moving contacts of both of the sets.

7. Electrical switch accessory according to claim 4, 5 or 6, wherein an upper body part fits over the lower body part and has formations contributing to pivotal mounting of a common rocker member for actuator elements for moving contacts of each of the sets.

8. Electrical switch accessory according to claim 7, comprising a detachable cover for the common rocker member.

9. Electrical switch accessory according to claim 8, wherein the detachable cover has a slot for attachment of a labelled part or a lens.

10. Electrical switch accessory according to any one of claims 4 to 9, wherein the or an upper body part fitting over the lower body part has openings allowing access to wire clamp screws of each of stationary contacts of each of the sets past a or said rocker member.

11. Electrical switch accessory according to claim 10, comprising a neon type said tell-tale unit is affixable to the upper body part with contacts going through openings to the stationary contacts of each of the sets at one end of the lower body part.

12. Electrical switch accessory according to any one of claims 4 to 11 wherein one way switch contacts to one side of said partition are replaced by an insert affording a surface substantially corresponding to tip locus of a or said actuator element concerned.

13. Electrical switch accessory corresponding to any one of claims 4 to 12, comprising cover fitting means affording alternative fitting to an accessory box according to thickness of the cover concerned.

14. Electrical switch accessory arranged and adapted to operate substantially as herein described with reference to and as shown in the accompanying drawings.