Description of Invention

This invention relates to the installation of lighting or other fittings in ceilings, particularly but not exclusively suspended ceiling structures.

Suspended ceiling structures, sometimes called "false ceilings", are well known. They comprise a supporting structure which characteristically is suspended from a load bearing ceiling structure of a building (which may also be the floor structure in respect of the next storey of the building above the one in question). The supporting structure carries a number of panels which form the visible ceiling of the storey in question. The space above the suspended ceiling panels may be used for installation of services such as electrical wiring, heating and ventilation ducting, and the like. The ceiling panels commonly are in the form of slabs or sheets of a thermally insulating material, and may be held to their supporting structure by the use of some form of fasteners, e.g. clips.

A light fitting or a fitting for some other purpose may be installed in such a suspended ceiling by providing an aperture of appropriate size in one of the panels of the ceiling and fixing the fitting in such an aperture. The fitting may be held in place by clips or the like which engage the panel. In such an installation, the weight of the fitting is borne by the panel.

One requirement for suspended ceilings is that they should prevent penetration of heat, if a fire should start in a room space beneath the ceiling, to the space above the ceiling panels. This is because, although a storey of a building may be divided into individual room spaces by partitioning beneath

the suspended ceiling, the space above the suspended ceiling panels is not thus divided and the undivided ceiling space provides a route for rapid spread of fire in a building. If penetration of heat, by radiation or convection, through the suspended ceiling can be minimised, spread of fire can be delayed and accordingly applicable standards for fire resistance of suspended ceilings are expressed in terms of withstanding fire beneath the ceiling and limiting transmission of heat to a certain value for a certain period of time.

As above referred to, the panels of a suspended ceiling usually are of a material having thermally insulating properties and hence the performance under fire conditions of a ceiling is dependent upon the integrity of the panels being maintained. One possible mode of failure is that of collapse of the panels, and if a fitting such as a light fitting is supported in a panel then the weight of the fitting means that the panel is more likely to collapse. Thus, hitherto, the installation of light fittings in ceiling panels has caused the fire resistance thereof to be adversely affected. A similar problem exists in ceilings, other than suspended ceilings, in which light fittings are installed in panels eg of plasterboard: the weight of the fitting renders collapse of the ceiling more likely in the event of fire.

Accordingly it is an object of the present invention to overcome or reduce this disadvantage of known light fitting installations in ceilings especially suspended ceilings. Other objects and advantages of the invention will become apparent from the following description of the invention in general terms and in specific embodiments thereof.

According to one aspect of the invention, I provide a fitting with retaining means, adopted to be disposed in an opening in a ceiling panel and to be retained therein by the retaining means wherein the retaining means is adapted to engage the fitting and to extend laterally therefrom and to have supporting equipment with a member at a position spaced from void opening,

whereby a part of the panel adjacent said opening does not bear at least part of the weight of the fitting.

Whilst it would be within the broadest scope of the invention for the retaining means to be adapted to engage the panel itself at a position spaced from the fitting and the opening wherein it is disposed, thereby achieving a "load spreading" effect and so rendering the panel more resistant to collapse in a fire, preferably the retaining means is adapted to engage a supporting member or structure of the panel, so that it can assist in supporting the panel.

According to another aspect of the invention, 1 provide a fitting with retaining means, adapted to be disposed in an opening in a suspended ceiling panel and to be retained therein by the retaining means, which panel is supported at at least one edge by a support structure, wherein the retaining means is adapted to engage the fitting and extend laterally therefrom for engagement with said support structure of the panel.

According to yet another aspect of the invention, I provide a ceiling comprising a support structure; a ceiling panel which is supported by said support structure; a fitting disposed in an aperture in said panel, and a retaining means engaging the fitting and extending above the panel laterally from the fitting to engage the support structure.

Preferably the ceiling is a suspended ceiling with the panel being edge- supported by the support structure, whilst the retaining means engages the support structure at an edge of the panel.

Whilst it would be within the scope of the broadest invention for the retaining means to extend laterally in one direction to engage the support structure at a single point or region, preferably, however, the retaining means extends laterally from the fitting to engage the support structure at two or more spaced positions along the edges of a panel. Preferably it extends in directions generally opposite one another from the fitting.

In suspended ceiling installation in accordance with the invention, the weight of the fitting is at least partially, and preferably entirely, borne by the support structure of the suspended ceiling rather than by the panel in which the fitting is installed. Thereby the above described disadvantage of carrying the weight of the fitting by the panel, contributing to collapse of the panel in the event of fire, is substantially overcome. Indeed, the fitting can, if its weight is borne by the support structure, assist in supporting the panel and make it even less likely to collapse than if no fitting were present.

Preferably the fitting engages with the panel in such a manner as to support the panel in the region thereof adjacent the aperture in which the fitting is disposed. For example, the fitting may be provided with a flange extending beneath the panel.

The nature of the fitting may be such that it provides a barrier to heat transmission upwardly through it. However, if the fitting does not inherently provide such a barrier, or even if it does, there may be provided a heat shield member substantially enclosing a portion of the fitting which lies above the panel.

Such a heat shield member conveniently is of metal and may be a pressing or pressings of sheet metal, e.g. steel.

Preferably the heat shield member is provided with a covering of a material which, in the event of fire, acts as a thermally insulating barrier. Preferably such a covering is an intumescent coating, e.g. a suitable paint. Use of a suitable intumescent paint coating enables heat transmission to be resisted for a long time.

The fitting preferably comprises a portion defining a formation generally in the form of an annular groove, and the retaining means may then engage with said formation and extend outwardly therefrom to engage the support structure of the ceiling.

The retaining means may comprise a retaining member having a part- circular formation which may have snap-engagement with such an annular groove formation, and at least one limb extending from said part-circular formation to engage the support structure.

The retaining member may be of wire of sufficient rigidity to support the fitting and to have said engagement therewith.

According to yet another aspect of the invention, I provide a fitting having a heat shield member substantially enclosing a portion of the fitting which, when the fitting is installed in a ceiling panel, lies above the panel; the heat shield member comprising a covering of an intumescent material.

The invention will now be described by way of example with reference to the accompanying drawings, of which :-

Figures 1 and 2 are respectively a sectional and a plan view of a light fitting installed in a suspended ceiling, in accordance with the invention;

Figures 3 and 4 are partial sectional views through further embodiments of light fitting and showing the engagement of retaining members therewith;

Figures 5 to 7 are plan views showing light fittings and further possible configurations of retaining member engaging therewith;

Figures 8 and 9 are respectively a sectional elevation and an exploded perspective view of a further embodiment of light fitting and retaining member engaging therewith.

Referring firstly to Figures 1 and 2, these show, respectively in a sectional and a plan view, part of a suspended ceiling which comprises a support structure having members 10, 11, 12, 13 forming part of a grid structure of such members. The members 10, 12 are parallel to and spaced from one another while the members 11, 13 are also parallel to one another and spaced from one another, extending at right angles to the members 10, 12. The members 10 to 13 are of generally T-section metal members, and they are

supported in a manner which is conventional and well known for suspended ceilings from a load bearing ceiling/floor structure of a building. A ceiling panel supported by the support structure of members 10 to 13 is indicated at 14 and this is a sheet or slab of suitable material such as a mineral fibre material. The panel 14 rests on the facing lower flanges of the members 10 to 13 so that the panel is supported along its edges, and fastenings such as clips may be provided for fastening the panel in such a position.

A light fitting indicated generally at 15 is installed in a central aperture in the panel 14. The light fitting comprises a base 16 of annular form, and an annular flange 17 lies beneath the region of the panel 14 immediately surrounding the aperture therein. Upwardly from the base 16 there extends a generally conical reflector 18 which may be of metal, e.g. an aluminium alloy, and which at its upper end carries a lamp holder 19 for a lamp 20 which as illustrated is a low energy consumption lamp of compact fluorescent type.

Also extending upwardly from the base and externally of the reflector 18 is a heat shield member 21 which from the base 16 is initially cylindrical and then has a frusto-conical portion leading to a dished upper end at which it is closed apart from having an aperture to receive the lamp holder 19. The heat shield member 21 is of metal, e.g. steel, and is formed as a pressing or as a number of pressings secured together, and is covered with an intumescent paint coating which swells when subjected to temperatures above a pre-determined level to form a highly heat-resistant enclosure for the light fitting. Preferably the intumescent coating is on both inner and outer surfaces of the heat shield member.

Engaging the light fitting just above the panel 14 is a retaining means which in Figures 1 and 2 is a wire retaining member. The retaining member comprises a part-circular portion 22 which embraces the light fitting and holds the latter by virtue of having snap-engagement with an annular groove

formation on the light fitting. From the portion 22, two limb portions 23, 24 extend in opposite directions away from the light fitting and at their free ends the limbs 23, 24 are bent into U-shaped portions 25, 26 respectively. The portions 25, 26 overlie members 1 1, 13 and, by virtue of inherent resilience in the wire of which the retaining member is formed, bear down on the members 11, 13 so that substantially all the weight of the light fitting 15 is carried by these members. Also shown in the drawings is a choke unit 27 carried by the limb 24 of the retaining member and from which an electrical cable 28 extends to the lamp holder 19.

Figure 3 of the drawings shows in an enlarged view one possible mode of engagement of the retaining member as described above with the light fitting 15. In this figure, the annular base 16 of the light unit is shown and it will be noted that it has at its upper periphery an overturned lip 29 defining a downwardly facing annular groove receiving the portion 22 of the retaining member. Part of the reflector 18 and heat shield member 21 are shown, these being secured to the annular base 16 by a plurality of rivets 30 spaced circumferentially about the base. The flange 17 is actually provided at the lower edge of the reflector 18.

Referring now to Figure 4 of the drawings, this shows part of a light fitting which is of different design from that above described. In this embodiment, it comprises a base 40 with a flange 41, a reflector 42, and a heat shield 43 extending from an upper part of the base 40. The base 40 defines an outwardly facing annular groove 44 with which a retaining member 45 of the configuration above described engages.

Referring now to Figure 5 of the drawings, this shows a light fitting indicated generally at 50 and which may be as described above with reference to Figure 4. A retaining member 51 is provided which is of wire and comprises an elongate U-shaped portion 52 of sufficient length to extend from a light

fitting mounted in the centre of a suspended ceiling panel to engage the support structure at an edge of such panel. One limb 53 of the portion 52 is provided with a part circular portion 54 leading into a relatively short straight portion 55 at its free end. The other limb 56 of the portion 52 continues straight and, in its free state, parallel to the limb 53 and portion 55 to a free end portion at 57 which, as for the portion 52, is of sufficient length to engage a support structure of a ceiling panel.

An annular groove on a light fitting as 50 is engaged by the part-circular portion 54 and the opposed straight portion of the limb 56 of the retaining member. To hold the retaining member in engagement with the lighting fitting, a wire clip 58 is passed over the free end portion 57 and the portion 55 of the retaining member, to hold these portions against movement away from one another and thus against disengagement from the light fitting.

Figure 6 shows a modification of the embodiment of Figure 5, in which two wire retaining members 60, 61 are utilised, each having straight free end portions and a part-circular centre portion as indicated at 62, 63, respectively. The portions 62, 63 engage opposite sides of an annular groove provided on a light fitting, and the retaining members are held to one another by two clips 64, 65 disposed one to each side of the light fitting.

Figure 7 shows a light fitting which is provided with two retaining members 70, 71 each having straight free end portions and an intermediate part- circular (slightly more than semi-circular) portion as indicated at 72, 73. The portions 72, 73 are each able to have snap-engagement with an appropriate annular groove or grooves provided on a light fitting. Preferably such retaining members are disposed in such a way as to provide four-point support of the light fitting from the edge-supporting structure of a ceiling panel.

Referring now to Figures 8 and 9 of the drawings, these show a further embodiment of light fitting which is circular in plan view. It comprises a frontal

flange 110 from which a body portion 111 extends rearwardly, the body portion 11 1 affording an annular recess 112 with a base 1 13. Behind the poition 112, the body 111 has a portion 109 which extends inwardly followed by an annular rearwardly and outwardly extending poition 108 which defmes a radially outwardly facing annular groove 107. The groove 107 provides for mounting of the light fitting in, for example, a panel in a suspended ceiling in the manner described hereafter.

The light fitting receives a dichroic lamp assembly indicated generally at 115. The lamp assembly 115 is supported in the light fitting by a mounting member 122 which has forwardly and outwardly oppositely extending arms 126 provided at its ends with respective pivot formations 130. The mounting member 122 further holds the lamp assembly 115, and a ceramic connector block 120 by which an electrical connection is established with the lamp assembly 115. Electrical cables 105 extend rearwardly from the connector block 120.

The assembly further comprises a cup shaped heat shield member 136. The heat shield member has a front rim poition 137 and a rear portion 138 defining an aperture through which the lamp and mounting member assembly extends. The rear portion 138 includes two opposed part-cylindrical formations which partly embrace the ceramic connector block 120 when the light fitting is assembled.

The heat shield member 136 has two oppositely disposed openings 139 through which the end parts of the arms 126, with the pivot formations 130 thereon, extend. The assembled condition of the light fitting, as shown in Figure 10 is reached by firstly fitting the mounting member and a lamp assembly to a heat shield member, and then fitting such sub-assembly rearwardly into the light fitting, resiliency deforming the arms 126 towards one another until their pivot formations 130 are able to snap into engagement with the base 113 of the recess 112 of the light fitting. Normally one of the pivot formations 130 would be thus engaged, followed by the other formation. The dimensions of the parts are such that when

such assembly has been carried out, the rear surface of the heat shield member 136 has contact with the light fitting in a substantially uninterrupted line in the annular region between the parts 109, 108 of the light fitting. By virtue of this, there is no or virtually no clear passage between the front and rear of the light fitting. The light fitting thus achieves a high fire safety raring for use in suspended ceilings or the like, by resisting heat transfer upwardly through the fitting.

The assembly of lamp and heat shield is able to tilt and rotate in the light fitting. Rotation through an angle of more than 180° may be prevented by providing pressed indentations 140 in the base 113 of the recess 1 12 in die light fitting, to be contacted by the formations 130 on arms 126. The front rim portion 137 of the heat shield member may be able to pass just beneath the edge of the flange 110 of the light fitting as shown in Figure 10, to provide a detent so that such a position of maximum tilting can be held in a vibration-resistant manner.

When the light fitting is to be installed in a suspended ceiling, an insulating washer as shown at 104 would be interposed between the flange 110 and a panel of such ceiling. The light fitting may be retained in such a panel by a retaining member 143 which as shown in Figure 11 may take the form of an elongate length of thick metal wire with a part-circular portion 144 which is able to be snap engaged, by resilient deformation, with the groove 107. The ends of the piece of wire take the form of limbs long enough to extend to rest upon the panel supports of the suspended ceiling, so that the weight of the light fitting is borne by the supports rather than the panel. A transformer or other low voltage electrical power supply for the halogen lamp assembly or an electrical connector block, may be carried by an end of the retaining member 143, as above described.

Alternatively a spring clip or clips may be used to retain the light fitting in a ceiling panel. One such clip may be used in conjunction with a retaining member having one limb only extending from a part-circular portion engaging the groove 107. Even if not required for retaining the light fitting in a panel, e.g. if two spring

clips are used, a retaining member engaging the groove 107 may be used to cany a transformer or a connector block.

The heat-insulating washer 104 could if desired be shaped to extend from the region of the flange 100 to overlie additionally the portions 11 1, 108 of die light fitting. If this is done, a further improvement in the fire safety rating of the light fitting is obtained, by preventing high temperatures being reached behind the fitting.

As illustrated, the light fitting shown in Figures 8 and 9 does not have an external heat shield member such as the heat shield member 21 illustrated in the embodiment of Figures 1 and 2. Such a heat shield member substantially enclosing the part of the light fitting which extends through an aperture in a ceiling panel above such panel may not be necessary because the light fitting by virtue of its internal construction does not provide a clear passage for heat to penetrate to the space above a ceiling panel. In addition, the light fitting utilising a dichroic halogen lamp assembly is inherently an extremely compact unit, and in any event does not provide a large path for heat penetration, as long as the ceiling panel does not collapse in the event of a fire. Since this latter possibility is unlikely to occur, by virtue of the arrangement of the retaining member of the light fitting and its engagement with the support structure of the suspended ceiling, a high fire safety rating is achieved. However, it would be possible, if desired, to provide an external heat shield member analogous to the heat shield member 21 having an intumescent coating.

In the above described embodiments, the fitting installed in the suspended ceiling is a light fitting. However, it will be appreciated that the principle of the retaining means used in the invention could also be applied to the installation of other fittings. By way of example, such otfier fittings could be loudspeakers, smoke detectors, or heating or ventilation fittings such as thermostats or even inlet outlet fittings for ducting. In each case, the prevention of heat passage by way

of the fitting itself, and the support of the ceiling panel, provides a high fire safety rating.

In the above described embodiments, the retaining member engages the support structure of a suspended ceiling panel. However, the principle of utilising a retaining member extending laterally from a fitting to engage a member spaced from the fitting can provide for improved safety under fire conditions for other types of ceiling panel, eg a traditional plasterboard ceiling. To engage even the panel itself by a retaining member can provide a load-spreading effect and help to resist collapse of the panel in a fire.

The features disclosed in the foregoing description, or the accompanying drawing, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.