GB2196491A - An electrical accessory eg. a ceiling rose - Google Patents

Abstract

During assembly of the electrical accessory which has a base plate 16 and a housing (22), wire clamp screws (36) and connection blocks (28) are inserted sequentially into recessing (26) of the housing (22) and the recessing (26) is subsequently closed off. The recessing may be closed off by the base plate. Alternatively, the base plate and housing are integrally formed with the recessing being closed off by a further plate (119). A closure member (130) may be hinged to the base plate. <IMAGE>

Description

SPECIFICATION Electrical ceiling rose This invention relates to electrical accessories suitable for mains use, specifically to ceiling roses intended for lighting circuits at outlets to lamps whether via a drop cord or an adaptor for a plug-and-socket system or for a batten type device.

Ceiling roses generally have circular base plates by which they are affixed to a ceiling and on which are mounted electrical connection provisions for wires entrant via knock-out holes in the base plates and for drop cords exiting through centrally apertured covers releasably fitting to the base plates. A particularly successful design of ceiling rose provided live, neutral and third terminal blocks in a line and with a common insulating cover thereover, access to wiring holes of said blocks being below the common cover, and access to connection screws of the blocks being through holes in the top of the common cover. Location of such line of terminal blocks was conveniently in a trough in the base, then usually with the terminal blocks canted to facilitate access thereto, particularly for mains wires.To permit choice of central or offcentre mains wire entry, also screw fixing for the base-plate at diametrically disposed holes required for standard fixing boxes, the line of terminal blocks was offset, typically running between ten o'clock and two o'clock for a suitable orientation of the base-plate with mounting holes at three o'clock and nine o'clock, then with an earth terminal at four o'clock or eight o'clock, usually between central and off-centre knockouts, or thereabouts.

It is an object of this invention to improve upon such a ceiling rose whether as to convenience of use or as to convenience and economy of manufacture or, preferably, both.

According to one aspect of this invention, a ceiling rose or other electrical accessory base has affixed thereto, whether formed separately and then secured in place or formed integrally therewith a housing member recessed for locating connection blocks and with side access to wiring holes of those blocks and further recessed to locate wire-clamp screws for going into those blocks transversely of and intersecting the wiring holes and with top access to heads of those wire clamp scews, assembly being with the wire clamp screws inserted first and separate from the terminal blocks for screwing into those terminal blocks only later, preferably at installation and wiringup by an electrician or other user.

Such ceiling roses with wire clamp screws disengaged from terminal blocks facilitate installation as the wiring holes are always clear.

A suitable housing member of insulating material made separately and secured to the base by one of its surfaces is recessed from that surface and its terminal blocks become captive in the housing member after its securement to the base. Then, the wire clamp screws may conveniently be retained and guided by their heads in extensions of said recessing.

A suitable housing member formed integrally with the base will permit access to its clamp screw and terminal block locating recessing from the underside or bottom of the base, which access can then be closed off by a cover plate.

There is, of course, an advantageous manufacture or assembly aspect arising, particularly in facilitating automated assembly without any subassembly step for engagement of wire clamp screws in the terminal blocks.

According to that aspect, assembly of a ceiling rose base comprises first installing wire clamp screws head-first into extensions of recessing of a terminal block housing member then installing terminal blocks into said recessing, and afterwards closing off the recessing of the housing member, whether by an insulating base member secured at mutually contacting surfaces about said recessing of the housing member, or by a plate secured over recessing of the base.

Such assembly is well-suited to securing the housing member on the plate from above, whether using a nest containing the housing member, or a plate onto the base as such, conveniently by ultrasonic welding, but other securement means could be used, for example by way of adhesives or other welding process. Location fits of the terminal blocks in the housing member could, of course, allow subassembly of wire clamping screws and terminal blocks separately into the housing member for its later affixment onto a base-plate member other than with the latter above the subassembly. However, the previously indicated process is manifestly advantageous particularly for automated assembly.

We do not exclude from the scope of this invention the possibility of a base-plate member having specific indented and/or projecting location and/or affixement formations relative to a housing member, or mutually co-operating formations of both. However, the potential for use of simple mouldings should also be apparent.

Regarding the shape of a suitable housing member and the disposition of its terminal blocks, it is preferred to have four such blocks, one of which serves for earthing purposes. That considerably facilitates wiring-up by not having to take earth wires to a different location spaced from the housing member.

Whilst, even so, it is feasible to have the terminal blocks and housing member in a straight line as for the above-mentioned prior successful ceiling rose, that could require the terminal blocks to be reduced in size from what we presently prefer to use, or force a change of its orientation or location on the base-plate say so as to run across rather than parallel to the location diameter of standard mounting holes. An alternative, as will be spe cifically described, allows retention of pre sently-used three-wire terminal blocks for live and neutral and two-wire terminal block for switch return, with addition of a two-wire ter minal block for earthing purposes, preferably with the latter between the live and neutral terminal blocks. Terminal blocks with other numbers of wire holes are, of course, feasible.

That alternative constitutes another aspect of invention and is for an arcuate housing member located adjacent to the periphery of the base-plate, preferably extending for more than 100 degrees of included angle but suffici ently less than 180 degrees to assure satis factory clearance of both mounting holes where, as is further preferred, the housing member extends between rather than about either of such mounting holes. We find that included angles between about 125 degrees and about 150 degrees give good wiring ac cess and facilitate provision of strain-taking lugs for wires of lamp cord drops either as integral extensions to ends of the housing member going close to but clear of the mounting holes or as portions of parts up standing from the base-plate and otherwise serving to locate ends of the housing mem ber.

Good wiring access has been mentioned and, for an arcuate terminal block housing member, there is substantial advantage in us ing a cable-entry knockout or other provision substantially centrally opposite the housing member and displaced therefrom by half or more of the diameter of the base plate, which generally allows wiring up using similar if not the same lengths of unsheathed cable wires.

Cable entry provision may be yet further facili tated when it is at a slot formation of the base that is selectively closed off peripherally by part of another ceiling rose part movable for that purpose, say its cover, which cover may be hinged and/or secured relative to the base by a third part interengaging with both, and such features constitutes further aspects of invention.

Placing of the earth block between live and neutral blocks is found to be particularly ad vantageous in minimising cross-overs of un sheathed cable wires.

Wiring-up can, of course, be by pushing bared ends of wires into terminal block holes close to and substantially parallel with the base plate member. If angled access is preferred, it can be provided, even with arcuate housing members, say by the simple expe dient of changing the angles of wire receiving holes in the terminal blocks.

Specific implementation of this invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through one embodiment of a ceiling rose omitting terminal blocks; Figure 2 is an interior plan view of its base plate showing terminal blocks; Figure 3 is a perspective view of a complete base-plate of Figure 2; Figure 4 shows an assembly sequence; Figures 5 to 8 concern another embodiment with hinged base and cover parts and a third part, Figure 5 being a top plan view of a base part, Figure 6 a bottom plan view of a cover part, Figure 7 a bottom plan view of the third part, and Figure 8 a section through assembled base outlet and third parts; Figures 9A, B, C are fragmentary plan and sectional views for preferred hinging between base and outlet parts;; Figures 10A, B are fragmentary plan and side views of preferred edge slottings of the base part; and Figures 11A, B, C are fragmentary sectional and plan views for preferred latching between outlet and third parts.

In Figures 1 to 3, a ceiling rose 10 comprises a circular base-plate i2 and cover 14 interfitting by screw-action or snap-fitting at the edge of an insulating base-plate member 16. The cover 14 has the usual central aperture 18 for a lampholder drop cord (not shown).

The base-plate member 16 has two mounting holes 20A, 20B at standard spacings on a diameter. Secured on the base-plate member 16 is a terminal block housing member 22 shown as being generally arcuate and disposed to one side and substantially symmetrically of the mounting holes 20A, 20B. Cord drop wire-strain lugs 24A, 24B could be integral with the housing member 22 extending from its ends to positions close to but clear of the mounting holes 20A, 20B. However, these lugs 24A, 24B are actually shown on upstands 25A, 25B integral with the baseplate member 16.

The housing member 22 is recessed from its surface in contact with the base-plate member 16 at four positions 26S, L, E, N in Figure 2 which recessing is extended sideways at positions of terminal blocks 28S, L, E, N which assists rendering same captive, see particularly (conventional) dashed lines 26 and (unconventional) full lines 28 in Figure 2.

The recessing 26 is shown extending at 30S, L, E, N through inner arcuate side 32 of the housing member 22. It will be the case that recessing of the housing member 22 at the position of the terminal blocks 28 will be extended above the wire entries 30, see dashed line 34 in Figure 1, though such extension may go higher. In any event, such extension will be further extended to form guiding and location means, whether by capturingly reduced ends or by sliding but interference fitt ing, for heads 36 (Figure 2 only) of wire clamp screws. Only one such further extension is indicated by dashed lines 38 in Figure 1, but it will be appreciated that each of the holes 40 of Figure 3 will communicate with such a further extension (38).

Those further extensions 38 are illustrated as being in a top part 42 of the housing member 22, actually above a shoulder 44 from its terminal block housing portion. It is intended that the top part 42 entirely accommodate wire clamping screws inserted therein from the recessing of surface 46 of the housing member before installation of the terminal blocks 28. Guidance and retention afforded for those screws at 38 assures that the screw need be engaged in screw holes of the blocks 28 only as and when later required, i.e. after sales and by installers. If capturing rather than grip retention is afforded for a screw head at 38, the holes 40 will be smaller than the screw heads 36, but obviously big enough for passage of a suitable electrical screw-driver.

Wire-entry holes of the terminal blocks 28 are shown at 50 S, L, E, N only in Figure 3 and are readily entered by bared ends of cable wires pushed in substantially parallel with the base-plate member 16.

If desired, of course, such wire-entry holes 50 could be formed inclined in the blocks 28.

Substantially equal lengths of unsheathed cable wire can be used for wiring-up if cables are entrant at an appropriate position on the base-plate member 16, see knockouts 52 shown substantially centrally opposite the housing member 22 and spaced therefrom by half or more of the diameter of the base-plate member 16. That, of course, makes wiring-up a great deal easier than hitherto when there would have been an earthing terminal at about the position of reference numerals 20A or 20B.

Assembly can probably best be visualised relative to Figure 4. Then, the housing member 22 can be in a suitable nest for first insertion of wire clamp screws, followed by insertion of terminal blocks, followed by application of the base-plate member accompanied or followed by suitable securing assurance, e.g. ultrasonic welding, see Figure 4.

In Figures 5 to 8, a generally circular base part 110 has a cut-out 112 from its edge to break-out formations 112A, B, C for mains cables. Alternative knock-out entries for mains cables are substantially central, see 114A, B, C between mounting screw hole provisions at 116A, B. The base part 110 has an integral arcuate connector block housing 118 for connector blocks with clamp screws will be accessible through holes 122L, N, E, S in the top of an upstand 120 of the housing 118 and correspond with connector blocks indicated dashed at 124L, N, E, S having wire entries at 126L, N, E, S through the inner wall of the housing 118. Assembly will be into recessing of the base 110 at the housing 118 and subsequently closed off by a plate 119.

Drop-cord wire strain lugs are indicated at 118A, B extending from ends of the housing 118.

An outlet part 130, also of general circular shape, is shown incorporating, at 132, a socket. As for the base part 110, the outlet part 130 is mainly of flat piate-like form, but it has portions 134 and 136 extending away at substantially diametrically opposite positions, the former (134) to fit into the cut-out 112 of the base part 110 and the latter (136) as a lug to fit into a slot 138 in the housing 118 of the base part 110. Indents 136A on the lug 136 and pips 138A on sides of the slot 138 can serve for snap-fitting into a hinging association. Then, the outlet part 130 will be generally spaced from the base part 110 but interlocated therewith via its extensions 134 and 136, actually in hinged relation.

A third part 140 is shown as a ring-like member of shallow cylindrical form and having at one end 142 thereof teeth 142A, B, C extending inwardly. The teeth 142A, B, C are to enter open slottings 144A, B, C in sides of the base unit 110 and go under blind extensions 146A, B, C of those slottings 144A, B, C. As shown, the third part 140 tapers and its widest end 142 carries the teeth 142A, B, C and overfits the edge of the base unit 110.

At its other end 148, the third part has notchings 148A, B, C whereby a tongue 150 of the outlet part 130 can pass through inturned rim 152 of the third part 140 and be held thereunder when the third part 140 is twisted into position on the base part 110 with its teeth 142A, B, C under the slotting extensions 146A, B, C.

The outlet part 130 has an upper edge rim 154, which can serve for snapping-on of a cover part (see dashed at 156) over a plug unit engaged in the socket 132. Alternative plug and socket systems can equally well be used, also the cover part 156 could be other than snap-fitting, say by mating screw threads. The outlet part 130 could be different, for example, a cover as for a ceiling rose, then with a central aperture for cord exit.

A preferred hinging arrangement between the base part 110 and the outlet part 130 is indicated in Figures 9A, B, C where a hinge pin 160 in the slot 138 tapers between rounded ends and is set at an angle suited to snap-fitting on of a restricted entry ended slot 162 of the lug 136'. A simple circular section hinge pin can be used and aids moulding.

A preferred arrangement of the slottings 144, 146 is indicated in Figures 10A and 10B, where an inner strengthening formation 164 extends along spaced lower and upper ledge formations 144' and 146'.

A preferred arrangement of notchings 148 and tongue 150 is indicated in Figures 11A and 1 1B where the notching 148' accepts the tongue 150' after deflection at fitting together.

The tongue 150' will require depression by a tool, such as a screwdriver blade, in order to be released from notching 148'. A braced stop formation is shown at 180 in Figure 11C to prevent undue deflection of the tongue 150'.

Claims (26)

1. A method of assembling an electrical accessory base having a housing for wire-clamp type connection blocks, the method comprising sequentially inserting wire clamp screws and connection blocks into recessing of the housing and subsequently closing off that recessing.

2. A method according to claim 1, where the housing is a member separately formed from a base plate, and wherein the base plate is used to close off the recessing of the housing member.

3. A method according to claim 1, where the housing is integral with a base plate, and wherein a closure plate is used to close off the recessing.

4. A method of assembling an electrical accessory base substantially as herein described with reference to the drawings.

5. An electrical accessory base made by a method according to any preceding claim.

6. An electrical accessory base comprising a housing on a base plate and recessed to locate connection blocks with side access to wiring holes of those blocks and further recessed to locate wire-clamp screws free of those blocks but to go thereinto transversely of and intersecting the wiring holes with top access to heads of those wire-clamp screws, the recessing being closed at the base plate.

7. An electrical accessory base according to claim 6, wherein the housing is made separately from the base plate and the recessing is closed by the base plate.

8. An electrical accessory base according to claim 6, wherein the housing is integral with the base plate and the recessing is closed by a cover or closure plate fixed to the base plate.

9. An electrical accessory base according to any one of claims 5 to 8, wherein all intended electrical connections are to connection blocks within said housing, including earth connection.

10. An electrical accessory base according to claim 9, wherein an earth connection block is between a live connection block and a neutral connection block.

11. An electrical accessory base according to claim 10, wherein a further connection block is next to the live connection block.

12. An electrical accessory base according to claim 9, 10 or 11, wherein said housing is arcuate and near the periphery of a generally circular said base plate.

13. An electrical accessory base according to claim 12, wherein the arcuate housing extends for more than 100 degrees but less than 180 degrees of included angie.

14. An electrical accessory base according to claim 13, wherein included angle for the arcuate housing extends between 125 degrees and 150 degrees.

15. An electrical accessory base according to claim 12, 13 or 14, wherein ends of the arcuate housing are spaced from mounting holes spaced on a diameter of the base plate.

16. An electrical accessory base according to any one of claims 12 to 15, wherein ends of the arcuate housing have strain-taking formations for wires of electric cord-drops.

17. An electrical accessory base according to any one of claims 5 to 16, wherein the base plate has electric cable entry provisions associated with a cut-out or slotting from its edge.

18. An electrical accessory base according to claim 17 as appendent to claim 13, wherein the cut-out or slotting is substantially centrally opposite the arcuate housing.

19. An electrical accessory base according to claim 1 7 or 18, wherein the cable entry provisions comprise base plate knock-outs extending from the cut-out or slotting.

20. An electrical accessory base substantially as herein described with reference to and as shown in Figures 1 to 4 or Figures 5 and 8, or Figures 9 to 11 of the accompanying drawings.

21. An electrical accessory with a base according to any one of claims 5 to 20 and comprising a ceiling rose.

22. An electrical accessory with a base according to any one of claims 5 to 20 and including a pocket.

23. An electrical accessory according to claim 22, further comprising a cover fitting over the socket.

24. An electrical accessory having a base according to any one of claims 5 to 23, a cover generally spaced from the base plate but interengaging same at spaced positions, and a third part engaging both of the base plate and the cover.

25. An electrical accessory according to claim 24, wherein the cover is hinged to the base plate.

26. An electrical accessory according to claim 25 as appendant to claim 17, wherein the cover has a formation entering said cutout or slotting of the base plate.