GB2233505A - Improvements in consumer units - Google Patents

Abstract

The capacity of a consumer unit is increased by connecting it to a second consumer unit by the use of a snap-fitting clip (21) arranged to engage releasably in apertures (15, 15a) in the adjacent sides of the two consumer units, a plurality of said apertures being provided for passage therethrough of electrical wiring. The clip has resilient limbs (127) with barb-like end parts (131) to cooperate with the interior surfaces of the sides. A cover for each unit has knock-out wall pans to accommodate said clip or for fitting over installed wiring/conduits passing through one or more of said apertures. A trim strip covers the gap between adjacent units. Connecting wires (74) between the units are attached to additional terminators (69) (at least for live and neutral) each comprising a tab-like extension having a bent up end (70) and a clamp device (72) of hollow square section fitting over said tab-like end. <IMAGE>

Description

Title: Improvements in or relating to consumer units DESCRIPTION The present invention relates to consumer units and in particular to the linking of consumer units to provide larger capacity from one or more base units.

Electrical consumer units are made in certain sizes to accommodate required switching provisions, the desired number of fuseways and any other circuits protection provisions. That traditionally results in the need to offer three or four-different sizes of unit with four to twelve fuseways. Tooling up to produce such different sizes of box is expensive, with larger sizes invariably costing more and yet not unusually having the lower demand.

Often electrical installation requirements expand after initial installation thereby demanding additional fusing requirements such that the electrician is faced with replacing the existing consumer unit with a larger one, or adding another consumer unit. The former option suffers from the disadvantage of rendering the original unit redundant, whilst the latter inevitably creates a hotch potch of units and wiring on the consumer supply board.

In aiming to overcome the aforementioned disadvantages attention has been given to producing just one (large) size of consumer unit and having the internals configurable for required numbers of fuseways thereby allowing for expansion within the unit and whilst this has attraction it means that the housing cost is high in view of the larger material requirements, even allowing for economies of scale, and generally there seems to be a prejudice in the trade against adopting such an approach.

Accordingly, the present invention provides a means of building up a required consumer capacity from two or more consumer units by associating those units.

Achieving association in a manner which provides for flexibility in disposition of the units relative to one another has been a prime consideration, as has maintaining options for cable entry and exit to the units. Where several units are to be associated the number of wiring entry provisions can be extensive often requiring all possible wire entry provisions to be utilised especially where routing of existing installed wiring has to be accommodated when additional units are to be introduced.

In arriving at the present invention then we provide a consumer unit, preferably having a casing of moulded plastics construction (but optionally metal with insulated carrier provisions for electrical connections), whose base has side walls providing a continuous boundary thereto for structural integrity and having, usually along at least two sides, usually opposites sides, preferably all four sides, one or more apertures, preferably defined between corner posts and/or intermediate web portions, as slots preferably open to a rear face of the side walls, which apertures/slots afford introduction of wiring to the consumer unit either free or via conduits. The apertures are conveniently dimensioned to receive the standard sizes of conduit, usually square or rectangular in cross section.

The consumer unit has a cover for fitting over the base and side walls of the unit and sides of the cover are configured to extend up to the mounting surface for the consumer unit and is provided with knock out wall parts to permit fitting over installed wiring/or conduits. Thus the structural integrity of the consumer unit is preserved whilst offering all possible available positions for wiring up as it is the cover that is configured for each application and easily replaced if wiring apertures should become redundant.

In designing for linking up of consumer units another aspect calls for providing the consumer unit with additional terminations for connecting wires between another unit or units. The terminations are provided at least for live and neutral preferably also for earth. In the case of the live and neutral these preferably run from the switched side. The live is provided with a bus bar for supplying such as circuit breakers and/or fuseways and the additional live termination mates with this. For the neutral, a neutral link is provided (hard wired) and the neutral termination preferably connects with this. In each case the additional termination is as a tab-like extension of the appropriate connection and in each case the terminal provision comprises a clamp device arranged to be received on the respective tab-like extension.That terminal provision preferably comprises a hollow square section to receive the tab -nd to clamp a wire up to the tab by a screw action device, preferably engaging the other side of the tab.

Preferably the tab has a bent end, preferably bent at 90 degrees with electrical connection being made beyond that bent end so that the end acts as a stop to prevent sliding off of the terminal provision. The terminal provision can accommodate up to 55mm2 of wire but will usually receive lOmm2, exceptionally 16mum2.

Such a terminal is useful for the earth line irrespective of whether required for connecting up multiple units as a strip of conductor material where the tab-like end can be formed with fingers to fit into two or more bores of an earth terminal block to provide for speedy wiring up of the earth without having to break up a large wire bundle.

Another advantageous feature is a bus bar shield which is cut away to allow access to fixing provisions for such as MCB's so avoiding the need to remove the shield exposing the entire live bus bar for alteration to one circuit. It is common practice to use a blanking plug for fitting to the cover to close off the opening in the cover when less than the maximum number of circuit provisions e.g. MCB's or fuseways are installed. A particularly advantageous arrangement results where individual blanking plates have a lip to one side to fit under an adjacent blanking plate as this improves the ingress factor. That lip can be cut off where only one plate is required.

The aforementioned live bus bar is preferably mounted to an insulated carrier secured to the base unit and the carrier provides a combination of full (to opposite ends) and half Din rails for mounting the isolation switches, RCB fuseways and such like.

In endeavouring to provide linking together of such consumer units in a convenient manner whilst achieving at least a certain degree of integrity of the assembly and without prejudicing valuable wiring capacity via the aforementioned apertures we arrived at a connecting link designed to use said apertures in a manner which maintains functionality of those apertures by allowing the passage of wiring from one unit to the other.

The link provides first abutment means for cooperating engagement with inwardly directed faces of the respective consumer unit bases to be linked together to resist separation once linked, and preferably second abutment means for cooperating engagement with outwardly directed faces of the respect consumer units to restrict closeness of spacing. The first and second abutments determine relative positioning of the consumer units. The first abutments depend from a common carrier which preferably extends transversely across the aperture.

In one embodiment of connecting link according to the invention the carrier is formed as a bridge member whose shape in cross-section conforms substantially to the wall configuration of the base defining the aperture so as to lie adjacent thereto in use, and defines limbs to support it from a mounting surface. The first abutment means are provided by oppositely directed arms each provided with means for retaining engagement with such as side wall surfaces of the respective consumer units being linked whereby to hold same in association. It will be understood then that the shape of the link is such that it straddles over any wiring or space therefor in a bridge like manner. Advantageously the bridge member provides a cover part extending between adjacent apertures of respective consumer units so that any interconnecting wiring is protected and obscured from view.Preferably the means for securing and retaining engagement of the link comprises barb like arms exhibiting some resilience so that the link fits in a snap fitting manner.

In a preferred embodiment of connecting link according to the invention the carrier comprises a opposite second abutments which cooperate with an outwardly directed face of the consumer unit base preferably also having side edges which cooperate with sides of the base. The tray-like member serves as a shield between cables passing through the aperturing and the surface to which the consumer units are fixed.

The first abutments are formed by a pair of spaced limbs each with shoulders to opposite ends, preferably positioned to extend widthwise from the limbs. More preferably the shoulders are inclined to give a wedging action in conjunction with the mating inwardly directed side walls (also inclined) of the consumer unit. The limbs exhibit a certain degree of resilience to afford assembly in a snap-fitting manner as a push fit into the apertures.

The present invention will now be described further by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a consumer unit base; Figure 2 is a plan view showing two interconnected consumer unit bases with covers removed showing basic detail; Figure 3 is a plan view of two interconnected consumer units with covers in place and showing trim strip; Figure 4 is a cross-section through the two interconnected base units; Figure 4a shows a detail of the terminal connections for the base unit; Figure 5 is a fragmentary plan view showing the interconnection of the two units according to one embodiment; Figure 6 is a sectional side view of the interconnection of Figure 5; Figures 7 to 9 are plan, side and end views of the connecting link as used in Figures 2 to 6;; Figures 10 and 11 are perspective views of two alternative embodiments of connecting units, and Figure 12 is a fragmentary section of the consumer unit bases showing interconnection with a link as per Figures 10 or 11.

Referring to the drawings, the consumer unit base 1 has a peripheral wall 3 comprised of an inverted channel 5, corner posts 7 and intermediate web portions 9 extending to a rear face 11 of the base unit formed by surface 13. Apertures 15 are defined in the sides of the base between respective webs 9 or webs at corner posts as at 15a. The webs 9 are inclined so that the walls diverge towards the base so defining an inclined face 10 to the webs. In the embodiment of Figure 1 five apertures are provided to each of two opposite sides although it will be appreciated that the number will be determined by the size of conduit to be accommodated and the size of the basic consumer unit. In the embodiment Figure 2 five equal sized apertures are provided to each of two opposite sides of the base unit.In both the illustrated embodiments the two remaining sides each have therein one aperture 17.

With regard to the apertures it will be noted that these effectively comprise slots open to the side of the unit and to the rear face of the consumer unit which facilities entry of wiring from the side or behind. The rear surface in the consumer unit 13 terminates along edge parts 19.

Figures 2 and 3 of the drawings show two nine module consumer units linked together by two connecting links 21. Two other embodiments of connecting link are described and shown in further detail with reference to Figures 10 and 11 hereinafter at side adjacent locations. One link may be sufficient. With reference to Figure 2 it will be seen that the two consumer units are placed side by side in direct alignment whereby the apertures 15, 15a of one consumer unit are in alignment with those of the other so that wiring may pass therebetween as required. It will be seen that the clips fit into the aligned apertures. It will be appreciated that the use of equal sized apertures in the two consumer units allows them to be linked wherever two such apertures can be placed in alignment.

Of course the two units could be placed staggered relative to one another and still interconnected which may be useful in certain applications. Figure 3 shows two aligned consumer units each provided with an individual cover 25 which is dimensioned to fit over and around the side walls of the consumer base. Fixing locations actually covered by blanking tabs are shown at 27 for securing means for locating in corresponding engagers 29 on the base units. Provision of such individual covers avoids the need for extra tooling for covers to suit multiple linked units but in order to provide an integral appearance a trim strip 31 is provided which fits over the gap between the two covers and embraces opposite ends of the covers.This conceals any otherwise visible wiring passing between the two consumer units and it will be understood that the desirability of providing such an integrated system makes it more preferable to mount the consumer units in alignment with each other rather than staggered. The two consumer units are shown adjoining along their longest sides but it will be appreciated that they could also be coupled with their shorter sides adjoining or indeed a combination of end and side fixing to build up the required number of ganged units.

It is then a simple matter of providing two or possibly three different lengths of trim strip to suit end or side mating of the units. The covers provided hinged lids over switching provisions and fuse ways etc.

The consumer units house such as isolating switches for live and neutral 62L, 62N, and fuse ways such as RCB circuit breakers 64 only one of which is shown in detail, and any other desired or required switching or testing provisions. A supplementary switch 66 is supplied with power from main unit and supplies subsidiary switches or fuse ways 64'.

A neutral link 68 connects from the switched side of 62N to the neutral terminals 68' and has a tab-like extension 69 with turned up end 70 with which a clamp device 72 is cooperable to wire in connecting cable 74 connecting to the other unit as at 66. The clamp acts to hold the cable 74 against the tab 69 with end 70 retaining the clamping device on the tab. The clamp device is fabricated into a hollow square section from a strip of metal and receives screw 76. The clamp device receives the tab and is supplied as an accessory to connecting up additional cables when units are to be linked. The line bus bar 60 has a corresponding terminal provisions 69L with bent end 70L as a tab-like extension. Tongues 60' are mounted for wiring in the required units such as protected fuse ways 64'. A similar tab 69E, 70E is provided for connecting in an earth line to earth strip 78.

A further feature is a line bus bar cover 80 which is stepped upwardly from the carrier tray through 90 degrees and extending over the bus bar 60, and then turning upwardly and again through 90 degrees to extend over the connection to the switching provisions as at area 82. In the illustrated embodiment a cut-out as at 84 is provided to leave access to fixing screws 83 so that the fuse ways and such-like provisions 64, 64' can be fitted or removed without having the bus-bar cover 80.

The lid 28 of top unit of Figure 3 is broken away to reveal internal switching provisions, e.g. MCB's 64 and also shows two blanking plates at 92, 93 as a snapfit with lip parts 94 engaging under a side edge of the housing recess 95 in the case of 92 and under part 92 in the case of 93 so preventing direct access through the recessed joint.

Another aspect concerns making improved connections at wiring connection blocks 68, 78 for which these blocks are set at a 10 degree inclination i.e. wire insertion face set at 10 degrees to normal vertical e.g. mounting surface. This is advantageous in creating an acute angle of the wire 82 at the terminal - see 80 - Figure 4a.

The connecting link illustrated in Figures 1 to 4 is now described in further detail with reference to Figures 8 to 9. The connecting link 21 has a tray like part 123 providing opposite edges 125 arranged in use to abut the edge 19 of the consumer unit base 13 to act as the aforesaid second abutments. Extending upwardly from opposite transverse sides of the tray-like part are limbs 127 connected by spine 129 but otherwise separate to afford resilience to the limbs.

Opposite ends of the limbs have respective fjst abutment surfaces 131 to the outer sides of the limbs and facing one another. In use these abutments abut inwardly directed sides 3 of the respective consumer units being linked actually at surfaces 10 of webs 9 which are inclined in conformation with the surfaces thereof. The inclination provides a vital wedging action of the connecting link against surface 12 on movement apart. The ends of the limbs are generally chamfered to assist in introducing them into the apertures. The connecting link affords provision for wiring through the apertures of the consumer unit by virtue of the channel way 135 as seen more clearly in Figure 9.

In use it is envisaged that one consumer unit base will be fixed to its mounting surface, the connecting link 21 inserted into an aperture 15 or 15a of that unit and then another unit connected up to the connecting link by way of corresponding aperture. That unit may then be fixed in position. The action of the connecting link is one of a snap fitting clip so is very quick to install and yet the provision of the first and second abutments positively locates together the two units.

As mentioned, the embodiments illustrated show a nine module consumer unit and it is envisaged providing units housing 6, 9 and 12 thereby allowing for doubling up to 12, 18 and 24 by mating with identical consumer units, which is preferred.

Reference is now made to Figures 10 and 11 in conjunction with Figure 12. Figures 10 and 11 illustrate an alternative embodiment of connecting link 21' and 21'' and Figure 12 illustrates such an embodiment connecting otherwise identical consumer unit bases to those previously described and like reference numerals have been used for corresponding parts. In each case the links 21' 21'' comprise a bridging part -35 turned down at the ends to form limbs 37 having surface contacting edges 39 which in use serve to urge the bridge member 35 up towards the upper boundary 12 of the aperture 15 and with the sides of the limbs 37 closely conforming to the sides of the apertures as defined by corner post 7 or intermediate webs 9. The link can be made of relatively thin plastics material so that the overall sizing of the aperturing is reduced only marginally thereby allowing passage therethrough of any wiring connections. The bridge part has longitudinally extending limbs 43 provided with shoulders 45 which in use are engageable with inwardly directed edges of the walls 5 so that the adjacent consumer units are held together. In the embodiment shown in Figure 11 the limbs 43 are relieved to their edges as at 47 to enhance - the flexibility where material requirements so dictate. It will be seen from Figure 12 that the bridge member 25 spans the width of the aperture and thereby obscures any wiring therebeneath.

Spacing between units is also limited by opposite edges 36 of limbs 37 abutting the opposite edges 19 of the respective consumer unit bases.

Claims (26)

1. A method of building up a required consumer capacity from two or more consumer units by associating those units.

2. A method as claimed in claim 1 in which association is by alignment of an aperture in each of two adjacent units.

3. A method as claimed in claim 1 or 2 in which association is by means of a connecting link.

4. A method as claimed in claim 3 when appendant to claim 2 in which the connecting link engages with the two adjacent units by way of the respective wiring apertures provided in the units.

5. A method as claimed in any one of claims 1 to 4 and further comprising providing additional terminations for live and neutral by way of tab-like extensions and a respective clamp device cooperating with said tab-like extension for wiring in the further unit.

6. A method as claimed in any one of claims 1 to 5 further comprising fitting a cover over each consumer unit by removal of knock outs in the side walling thereof to accommodate passage of wiring and fitting of a trim strip between adjacent covers.

7. A method of building up a required consumer capacity substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

8. A consumer unit for use in the method of claims 1 to 7 comprising a casing whose base has side walls providing a continuous boundary part thereto for structural integrity and wherein one or more of the side walls has one or more apertures therein for passage of wiring therethrough.

9. A consumer unit as claimed in claim 8 in which apertures are provided in at least two side walls.

10. A consumer unit as claimed in claim 8 or 9 in which the apertures are provided in two opposite side walls.

11. A consumer unit as claimed in claim 8 or 9 when of substantially rectangular configuration and in which the apertures are possible in the four side walls thereof.

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12. A consumer unit as claimed in any one of claims 8 to 11 in which the or each aperture is open to the rear of the unit as well as the sides.

13. A consumer unit as claimed in any one of claims 8 to 12 in which the sides are defined between corner posts and the apertures disposed between the corner posts and/or intermediate web portions.

14. A consumer unit as claimed in any one of claims 8 to 13 in which the or each aperture is dimensioned to receive a wiring conduit.

15. A consumer unit as claimed in any one of claims 8 to 14 comprising a cover for fitting over the base and side walls of the unit in which sides of the cover are configured to extend up to the mounting surface of the consumer unit and are provided with knock out wall parts aligned with said one or more apertures to permit fitting over installed wiring/conduits passing through said one or more apertures.

16. A consumer unit as claimed in any one of claims 8 to 15 further comprising one or more additional terminations for connecting wires between units.

17. A consumer unit as claimed in claim 16 in which the or each additional termination comprises a tab-like extension having a bent up end and receiving a respective terminal clamp device, with the clamp device comprising a hollow square section fitting over the tablike end and retained by the bent up end when done up.

18. A consumer unit as claimed in any one of claims 8 to 17 further comprising a bus bar shield which is cut away to allow access to fixing provision for such as MCB,

19. A consumer unit as claimed in any one of claims 8 to 18 when the casing is formed of a plastics moulding.

20. A consumer unit constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

21. A connecting link for use in the method of claims 1 to 7 comprising a body having means to engage each of the two consumer units to hold same together.

22. A connecting link as claimed in claim 21 in which said means comprises respective abutments for cooperating engagement with interiorly disposed faces of the consumer units and which fit into aligned apertures of the respective consumer units.

23. A connecting link as claimed in claim 22 in which the body part is configured to allow passage of wiring between the units through the aligned aperture.

24. A connecting link as claimed in claim 21, 22 or 23 comprising second abutment means for cooperating engagement with respectively outwardly directed faces of the consumer units.

25. A connecting link as claimed in claim 22 in which the abutment means are carried on pairs of laterally spaced resilient arms for snap-fitting engagement in said apertures.

26. A connecting link constructed and arranged substantially as hereinbefore described with reference to and as illustrated in Figures 5 to 9 or 10 and 11 of the accompanying drawings.