US3104833A

US3104833A - Recessed lighting fixture

Info

Publication number: US3104833A
Authority: US
Publication date: 1963-09-24
Anticipated expiration: 1980-09-24

Description

Septo 24, 1963 c. J. STUART ET AL RECESSED LIGHTING FIXTURE 2 Sheets-Shec-ztl l Filed Deo. 14, 1959 Sept. 24, 1963 c. J. STUART ETAL RECESSED LIGHTING FIXTURE 2 Sheets-Sheet 2 Filed Dec. 14, 1959 o ww .Nw \N um |Lp a United States Patent() The present invention relates to recessed lighting fixtures.

. 'Lighting fixtures of the type which in use are mounted in recessed relation inwalls, ceilings, or the like, encounter the problems of subjection of the wiring to possibly excessive heat developed by the lamp or light bulb employed in the fixture, and of the need for accessibility of the wiring from the interior of the fixture. The fixture construction of the present invention provides solutions to these problems representing improvements over previous structures of this type.

It is an important object of the invention to provide a recessed lighting fixture construction which greatly minimizes both the radiation and conduction of heat so as :to protect the wiring against the deleterious effects thereof, and at the same time provides for easy access to the wiring when desired.

Another object is the provision of a recessed lighting fixture in which substantially the entire interior of the fixture housing 4is shielded Afrom the radiant heat of the lighting means.

Another object is the provision of a recessed lighting fixture employing a heat-dissipating mount `for the lighting means provi-ding `a limited circuitous heat-conducting path between the lighting means and the housing to minimize transmission of heat to lthe housing.

A further object is the provision of a recessed lighting fixture in which a reflector is mounted in completely heat-insulated relation to the housing.

Another object of the invention is the provision of a recessed lighting fixture employing unitary means for both closing the wiring-access aperture and mounting the lighting means which also provides a heat insulating space and a heat baffle plate within the housing to minimize heat transfer to the wiring.

A further object is the provision of a recessed lighting fixture including a junction box mounted on and accessible from the fixture housing in which the junction box is spaced from the housing and an air passage or open ended chamber is defined between the box and housing to minimize heating of the `junction box.

Another object is the provision of a recessed lighting fixture Ihaving a junction box mounted thereon in spaced relation, inwhich a plurality of cooling air spaces or passages 'are provided to minimize transmission of heat to the box.

A rfurther object is the provision of ia recessed lighting fixture which includes a junction box mounted on the fixture housing in spaced relation thereto and with a cooling air passage defined therebetween, in which protective shielding means is provided for wiring extending through sai-d space -from the housing to the box.

lIt is also an object of the invention to provide a recessed lighting fixture in which a reflector is mounted on the top wall of the fix-ture housing in spaced relation thereto by a tubular heat-insulating spacer and a single fastening element itself' also insulated from the reflector.

Other and further objects, advantages, and features of the invention will be apparent to those skilled in the art from the following .detailed description, taken in conjunction with the accompany-ing drawings, in which:

FIG. 1 is a side elevational view of a lighting fixture according to the present invent-ion, with portions broken away and portions shown in section for greater clarity of disclosure;

FIG. 2 is a cross-sectional view taken substanually as indicated by the line 2-2 of FIG. l; and

FIG. 3 is a bottom plan view of the fixture with the closure removed.

Referring to the drawings, there is shown a fixture embodying the present invention, in which a housing generally indicated as 10 is defined by a rectangular top wall 11 and four side walls l12 extending from the edges of the top wall, with the side wall edges remote from the top wall defining an open bottom 13 of the housing. The fixture is illustrated as mounted within a ceiling C indicated in dotted lines, in which ian opening is formed of sufficient size to allow the insertion of the housing from below. A closure generally designated 14 is provided for the open housing bottom, comprising a rectangular bezel or trim member 15 in which i-s mounted a lens or plate of glass 16 or other suitable light-transmitting material. The trim member has a cross-sectional width sufficient to conceal lthe edges of the housing side walls 12 and of the opening in the ceiling C. About the glass-receiving opening of the trim member I15 extends a flange 17 which holds the glass 16 against lateral movement, and projects within the open bottom of the housing when the closure 14 is in its closing position, the flange 17 paralleling'lthe respective side walls 12 and being spaced inwardly therefrom throughout its extent. The closure is removably secured to the housin and held in closed position relative thereto, by a pair of spring members 18 pivoted on the flange 17 as by rivets 19 to extend yalong opposite side walls 12 of the housing 10, the spring members 18 engaging in slotted spring brackets 20 secured to suc-h opposite housing side walls as by screws 21. The spring members provide for a resilient connection yieldably holding the closure on the housing. Since the spring members 1S and brackets 20 form no part of the present invention, and may be replaced with other suitable means for accomplishing the same purpose, the details of construction and operation thereof are omitted. Any suitable means may be employed for mounting the fixture, but in the present instance there is illustrated a pair of mounting brackets 22 each having a plate portion 2.3` ldisposed against the interior of one of the walls 12 on which the brackets 20 are secured. Outwardly offset leg portions 24 extend yfrom the plate portion 23 of each bracket 22 and project through suitable apertures 25 formed in the ladjacent side walls 12, land extend parallel to the outer faces of the walls. Outwardly extending foot portions 26 on the Ileg portions are adapted to engage on the upper surface of the ceiling C, as best shown in FIG. 2, and to be secured thereto if desired. Slots 27 in the plate portions 23 receive therethrough screws 28 threaded through the side walls, to provide for vertical adjustment of the brackets 22 relative to the housing 10 so as to Idetermine the vertical position of the housing relative to the ceiling, as will be understood. In the present instance, the `foot portions 26 are not shown as secured to the ceiling C, the housing being secured by a clamping arrangement. The clamping action is provided fby a pair of mounting angle members 3G each of which has one leg 31 thereof extending into the interior of the housing along the adjacent Iside wall and secured by the screw 21 which secures the spring bracket 20. The other leg 32 of the ang-le member extends outwardly below the edge of the side wal-l to engage the lower surface of the ceiling C, so that the ceiling is in effect clamped between the foot portions,

extending legs 32 are concealed by the trim member 15.

connected at one endiby. a preferablyy integral wall,

35', and each having at the opposite end thereof an outturned ilange 37". .The box is completed by a bottom plate 38 and a cover plate 39, the plate 38 being secured in place by spot wel-ding to suitable flanges of the walls 35, and the plate 39 being removably secured in any well known manner. The side or end of the box 34 opposite that at which the wall 36 extends vis open so as to allow access into the box through the Yaperture 33, the box being mounted on the apertured side wall 12pt the housing by means of the flanges 37. These ilanges engage the inner surface `of the wall adjacent the oppositeY ends of the aperture y33 and are secured to the wall by means of screws 40. The plates 33 and'39 extend from the Wall 36 only a portion. of the distance between that end wall and the housing wall l2, the width of the

plates

38 and 39 being shown in FIGS. l and 3 as substantially half the -distance between the wall 36 and the llanges member or support member 4l ofgeneral U-shape inV cross section, comprising a closure plate 42 and a mounting plate 43 connected to the closure plate along one edge by'a preferably integral portion 44 which holds the plates 42 and 43 in suitably spaced and substantially parallel relation. The 'member4l is secured on the interior of the side wall l2, extending over the aperture 33, by meansof screws 45 extending through the closure plate 42 and the housing wall. Suitable apertures 46 are formed in the moun-t-ing plate 43 to per-mi-t application and removal of the'screws `45, as Will be clear from FIG. 2. As best evident trom FIGS. 2 and 3, the cover plate 42 overlies the llanges`37 of the junctionbox 34 and the securing screws 4d thereof. To accommodate the heads of these screws, the `cover plate is provided with appropriately located `apertures 47 (FIG. 2).

Secured to the U-shapedV support rnember4l is a U- shaped heat'balle means'extending between the walls 35. The baille means :comprise a pair of substantially parallel vertically arranged spacing plates 48 each having an inturned flange 49 secured to the closureV plate 42 as by spot -weldingand extending outwardly from the plate 42y to an integral transversely extending baille plate 50. The plate t) is disposed just within the adjacent edge portions of the

plates

38 and 39 of the junction box 34 and extends therebetween, as best shown in FIGS. l `and 3, to kdefine with'the wal-

ls

35 and 36 and the plates 3S and 39 a junction compartment 5l within which the wiring Econnections `for the xture are enclosed. The baille plate, as shown, is preferably slightly `smaller than the wall 36 to which it` lies parallel, but is of such dimensions as to substantially close the compartment, as is evident from the drawing. lt will be apparent that the compartment 5l may be considered as a junction box of smaller size than the junctionbox 34, held in spaced relation to the housing side wall by the porti-ons of the walls 35 extending between the'housing and the com' partment and in effect forming spacing extensions of .a pair of opposed walls of the box or compartment'Sl.'

chamber 52 defined between the walls 35 by the closure plate 42,. spacing plates 48, and baffle plate 50. This passage or vair chamber 52 permits free circulation of air between the housing and the'junction Ibox or compartment 5l Vto assist in maintaining the latter in a reasonably cool condition. Auxiliary air passages or spaces 53 (FIG. 3) are defined between the baille spacing plates 43 and the adjacent portions or extensions of the walls 35, and serve to cool the walls so as to reduce the possible conduction of heat through thewalls 35 to the junction compartment.

An electrical socket 55 for the light bulb (not shown) employed in the lixture is mounted on the mounting plate 43 by means of a screwA 56 or the like, an embossment 57 of the plate 43 engaging in a corresponding recess in the base of the socket to hold the socket against rotation without requiring more than one securing screw 56. A

disc 53 of heat-insulating material, which may also be electrically insulating, is disposed between the socket 55 I-t may l land the mounting plate 43 therefor to minimize conduction of heat therebetween. Wires 59 lead from the socket tothe junction box, passing through the chamber 52. Extending across the chamber 52, with itsY ends suitably received in apertures formed in the plate 42 `and lthe baille plate 50, is a tube 6l) of suitable heat insulating material which may also have electrical inusllatirrg properties,V

which encloses the portion of the wires 59 within the air chamber to protect the same from the effect of heat transmitted from the light bulb. The tube 4oil may be suitably held in place by being resiliently pressed between the closing plate 42 and baille plate 5u, which may be slightly distorted by the tube.

The junction box may be mounted on the housing 10 in initial assembly of the xture, and upon installation of the fixture, with the closure 14 and the rellector 6.1 removed, the wires 59 may be connected to the electrical conductors (not shown) leading from the mains to the junction box or compartment. `Such conductors ordinarily are protected by suitable rigid or flexible conduit an end of which may be lconnected to the' junction box. In making the wiring connections, several inches of excess or slack of the conductors is provided for, either by providing such a length of the conductors beyond the end ot the conduit, or inthe case of flexible conduit allowing such an ,excess of the conduitoutside of the junction box itself.- To make the connections, the U-shaped support member 41 with the socket 55 and the baille plate 50 carried thereby is disengaged from the housing by removal of `screws 45, and the conductors are drawn out to a point where their ends may be engaged with the socket lead wires 59. This may be done either by using the slack in the conductors or by moving the junction box inwardly upon removal `of screws 4t), as most convenient. The connections may thus be made either within the area bounded by the walls 35 or at a point inwardly of the plane of the sidewall. With the junctionbox supported by means of the llanges 37 secured to the housing Vby the screws 40, and with the connections completed,

Y ber 4l with the parts secured thereon may be removed .explained and ythe' wires 59 drawn inwardly of thehousing,` with or,

without the junction box being similarly moved inwardly orf the housing as already explained, to bring the connections within reach, either-through the laperture 33 or within the outline of the housing. Replacement of the parts may thereafter be made in the manner already The U-shaped support member 41 provides not only a closure for the aperture 33 affording access to the junction box, but also carries the baffle means and therewith defines the air passage or open ended chamber 52 and the auxiliary air spaces 53, as already explained. The member also serves as a mounting bracket for the socket 55. The member 41 preferably is secured in the housing in such fashion that the free edge of the mount-ing plate 43 is spaced from the housing so as not to contact .therewith and thus avoid providing a heat-conductive path thereto. Instead, the member 41 provides a restricted circuitous heat-conducting path Afrom the connecting portion 44 to the plate 42 and adjacent side wall, the connection ofthe plates 42 and 43 along only one edge thereof Iand the spaced relation of the plate 43 assuring such limited conductive path. The plate 4S is made substantially as shown, that is, of substantially the saine size las the plate 4Z, so that it may aid inthe dissipation of heat which may be transmitted thereto. Instead of spacing Athe plate 43 from the housing, it may, it desired, beV arranged to engage against any appropriate portion of the housing, such -as the top wall 11, to -rigidify the mounting of the socket 55and also to provide Ia second path for the conduction of heat to the xture housing for dissipation thereby, when the circumstances are such that such a second path is advantageous. The member 41 provides an insulating space between the plates 42. 'and 43 by reason of the spaced relation thereof, and also provides a heat baffle in addition to the baffle plate Sil which acts to minimize radiation of heat to the junction box.

In the housing there is provided the reflector 61, of suitably concave form, which is directed toward or farces the open bottom 1-3 of the housing. The reector is illustrated as `o rf frusto-pyramidal form, with a rectangular fiat top portion 62 from which ffour side walls 63 incline outwardly and downwardly to define the open lower edge 64 of the reflector. An aperture 65 is formed in one of the reflector side walls 63 to allow the socket 55 to project Within the reflector and hold the light bulb in proper position. As most clearly shown in FIG. 3, the reflector 6l at its edge 64 has a perimeter generally corresponding to the interior of the housing, but orf slightly Smaller dmensions, so that it is spaced from the housing and from the trim flange 117 at all points, and furthermore is spaced from all parts of the structure which contact the housing. By reason of such spacing, there is no conduction of heart from the lighting fixture bulb to the housing or other parts by the reflector 61. The top portion of the reflector is formed with la central aperture providing an edge portion which engages in la circumferential groove adjacent one end of a tubular spacer 66 formed of heat-insulating material. The spacerextends between the reflector and the top Wall 11 of the housing to receive therethrough a screw 67 the head of which is insulatingly spaced from the reflector by the end of the spacer lying within the reflector, and the threaded shank of which extends through a suitable aperture in tne top wall to hold the spacer 66 against the wall and thereby clamp the reflector securely in the `desired position. The reflector may be torrned of suitable sheet metal and may of course have a configuration other than that specifically disclosed. The relatively short length ot the tubular spacer 66 assures the necessary degree of stability of the reflector which could not be provided by a long spacing member.

j As shown in FIGS. l and 2, the Ireflector 61 extends within the flange 17 of the trim 1S, the edge or the reflector lying in a plane below the plane orf the edge of flange 17, so that the Harige Iand refiector extend in overlapping relation. The margin of the reflector, as already mentioned, is spaced from and surrounded by flange 1'7. Complete shielding of the Ihousing from heat radiated by the light bulb is thus achieved, since the flange 17 serves asa .deflector for rays from the light bulb, and by reason of its overlapping relation to .the reflector cooperates therewith to prevent heat rays impinging on the housing.

It will be evident that the provision of the socket-receiving aperture in the reflector instead of the usual edge slot contributes to the substantially complete shielding of the housing inte-rior. Except for heat absorbed by the reflector 61 and flange 17, all of the heat radiated by the light bulb either passes directly through the glass 16 of the housing closure 14, or is refiected therethrough. Since both the reflector 61 and the flange 1'7 are spaced from the housing and from each other, there is no conduction of heat therefrom to the housing and only such heat as is transmitted by convection or by re-radiation from the refiector or flange can reach the housing, together with such minor proportion as rnay be conducted through the insulating spacer 66 and screw 67 or pass about the socket 55 through the aperture 65'. Because of the confined locations in which lighting fixtures of the type herein disclosed are normally installed, the insulation of associated electrical conductors would be subjected to such a great concentration of heat as to deteriorate very quickly to the danger point, if special provision were not made to maintain the 'conductors at a reasonably low, safe temperature. The present construction accomplishes this in a most thorough and effective rnanner.

As .already pointed out, the U-shaped supporting member 4l provides both a baille and an insulating air space interposed directly between the source of heat and the junction box mounted on Ithe housing, and thus in large degree prevents radiation of heat to the wiring in the junction box. The conduction of heat through the socket 55, normally the coolest portion of the lighting means and as a practical matter heated only by the light bulb, is largely minimized by the heat-insulating disc 58 ldisposed between the socket and the member 4,1 and further by the limitation of the heat conductive path provided by the U-shaped construction of the member 41, `as previously explained. Transmission of lieat to the junction box by conduction from the housing is minimized by the fact that the only heat-conductive path to the junction box is through the walls 35. It is further reduced by the cooling effect of the open-ended fair spaces 52 and `53 on the walls 35, so that much of the heat being conducted through fthe walls is dissipated. The provision of the tube 6i) lfurther lim-its conduction of heat to the compartment 51, since in addition to protecting the wires 59 against the effects of radiated heat, it does not itself conduct any appreciable quantity of heat to the compartment 51, and provides a heataradiating surface to dissipate heat conducted through the wires 59 themselves.

We claim:

l. A recessed lighting fixture comprising a housing defined by side and top walls and having an open bottom, a junction box mounted on a side wall of said housing including a first pair of opposed walls secured to said side wall and a second pair of walls laterally termin-ating in spaced .relation to said housing side wall and connecting said first wall pair, `an opening in the side wall affording access to the junction box, a closure for said opening, a heat bafile plate carried by said closure in such spaced relation as to extend between said second pair oef box walls at the edge portions thereof adjacent the housing and between said first pair of walls to define a substantially closed compartment in said juncture box, means connecting said baffle plate .to the closure including a pair of plates integral with the baffle plate extending parallel to the walls of said first pair to define a pair of laterally outer open spaces therewith and to ldefine with said baille plate an inner open space between said compartment and the housing, .said closure comprising a pair of parallel plate members connected along one parir of adjacent edges, one of said plate members being secured to said housing side wall and extending over said opening and the other being spaced inwardly from the housing side wall and disposed out of contact with the housing, a heat-insulating tube extending between `apertures in said one plate member and said baffle plate to enclose wiring extending between the housing land said compartment, an electrical socket mounted on the other plate member, la heat insulating member disposed between said socket and other plate member, a concave reiiector in the housing having an aperture spaced from the edge `thereof receiving the socket therethrough, heat-insulating cally overlapping laterally spaced relation to the reliectory and spaced :from the housing side walls.

2. A recessed lighting fixture comprising ar housing defined by side and top walls and having an open bottom, a junction box mounted on a side Wall of said housing having a pair of opposed walls thereof terminating in spaced relation to said housing sidewall, an opening in the side wall affording access to the Vjunction box,'aV

closure for said opening, a heat baiiie plate carried by Y said closure in such spaced relation as to extend between said pair of box walls at the edge portions thereof adjacent the housing to define a substantially closed compartment in said junction box and an open space between said compartment and the housing, said closure comprising a pair of parallel plate members connected along one pair of adjacent edges, one of said plate membersV being secured to said housing side wall and extending over said opening and the other being spaced from the housing,

an insulating Vtube extending between apertures in said one plate member and said baffle plate to enclose wiring extending between the housing and said junction box compartment, an electrical socket 4mounted on the othery plate member, a concave reiiector in the housing extending over said socket, heat-insulating spacing means extending between the center of said reflector and the top wall of the housing and having a portion within the reflector, and fastening means securing the reflector in place extending from the reiiector to said top wall through said spacing means and held out of contact with the reiiector Vby the spacing means and holding the reflector out of contact with the housing.

3. A recessed lighting fixture comprising a housing defined by sidewalls and a top wall and having an open bottom, a junction box mounted on a side wall of said housing having a pair of opposed walls thereof said housing Vhaving a pair of opposed wallsV thereof terminating in spaced relation to said housing side wall, an opening in the side wall affording access to the junction Y box,ra closure for said opening, a heat bafiie plate carried Y terminating in spaced relation to said side wall whereby v terminating in spaced relation to said housing side wall,

an opening in the side wall affording access to the'V junc-` tion box, a closure for said opening', a heat baflic plate carried by said closure in such spaced relation as to extend between said pair of box walls at the edge' portions thereof adjacent the housing to dene a substantially closed compartment in said junction box and an open space between said compartment and the housing, said closure comprising a pair of parallel plate members connected along one pair of adjacent edges, one of said plate members being securedV to said housing side wall yand Vextending over said opening and the other being spaced from the housing, a heat and electrical insulating tube engaged in and extending between apertures in said one plate member and said baffle plate to enclose wiring extending between the housing and said junction box compartment, an electrical socket mounted on the Vother plate member, a concave reiiector in the housing for the aperture, lheat baffle by said closure in such spaced relation as to extend between said pair of box walls at the edge portions there- Y of adjacent the housing to define a substantially closed` compartment in said junction box and an open space between said compartment and the housing, said closure other plate member, a concave reflector in the housingl extending over the socket, and heat-insulating means mounting the reflector Vin the housing out of contact therewith.

5. A recessed lighting Yfixture `comprising la Yhousing defined by side and top walls and having an open bottom, an aperture in a side wall of the housing, a junction box mounted on said side wall accessible through said aperture, a closure for the aperture including a rst plate member secured to the side wall over the aperture and a second plate member secured to said first plate member only along an edge thereof and spaced therefrom, an electrical socket mounted on said second plate member, and a concave reiiector heat-insulatingly a iirst pair of opposed vertically disposed wall ymembers of the box extending and 4secured to 'the housing side Wall at opposite ends of the aperture, closure means means mounted on said closure means including a vertical baffle plate spaced from the side wall `extending between said first wall member pair and with said closure means defining an Y open-ended air chamber, said baffle means also including plate members integral with the bathe plate and extending' defining with said first pair and said baiiie plate a junction t compartment separated from said housing by said air chamber, said second pair of opposed wall members said opcn-ended air chamber and said open-ended air spaces communicate with the atmosphere surrounding the junction box so as to permit a iiow of air therethrough.

i7. A recessed lighting fixture comprising a housing having an apertured side Wall, a junction box having an open end, means mounting said box on said side wall in spaced relation thereto with said open end facing the side Wall, a first closure member for said aperture and a second closure member for said open end, at least vone of said closure members being resilient, and a tube of heat and electrical insulating material extending between said closure members and removably held in position by being resiliently pressed therebetween for protectively enclosing Wiring extending between the housing and box.

8.-A recessed lighting fixture comprising a housing l defined by side and top walls and having an open bottom,

a concave reflector in said housing directed toward said open bottom and having a central aperture, a tubular spacing member of heat-insulating material disposed betweenl said top wall and reflector and having a portion extending through said aperture, and a headed fastener extending through the aperture and spacing member into retaining engagement with the top wall and held out of contact withthe reflector by said vspacing member portion.

9. A recessed lighting fixture of ,the type set forth in claim 7 characterized by said closure members each having an aperture therein and said tube of insulating material having reduced end portions accommodated Within said apertures respectively.

References Cited in the le of this patent UNITED STATES PATENTS 1,418,671 Patterson June 6, 1922 1,580,090 Shoenberg Apr. 6, 1926 1,919,558 Johnson July 25, 1933 2,076,650 Kettron Apr. 13, 1937 2,233,947 Kantack Mar. 4, 1941 2,554,258 Lundquist May 22, 1951 10 Resek et al Dec. 4, 1951 Beber et al Dec. 27, 1955 McGinty et al Oct. 16, 1956 Isler Aug. 6, 1957 Kingman Oct. 21, 1958 McGinty Aug. 4, 1959 De Mauro Aug. 11, 1959 Bodian Apr. 4, 1961 Schwartz Aug. 22, 1961 OTHER REFERENCES Inspiration-Lighting, page M43, catalogue published by Moe Light Division of Thomas Industries Inc., Fort Atkinson, Wisconsin, date of publication, 1955.

Claims

4. A RECESSED LIGHTING FIXTURE COMPRISING A HOUSING DEFINED BY SIDE WALLS AND A TOP WALL AND HAVING AN OPEN BOTTOM, A JUNCTION BOX MOUNTED ON A SIDE WALL OF SAID HOUSING HAVING A PAIR OF OPPOSED WALLS THEREOF TERMINATING IN SPACED RELATION TO SAID HOUSING SIDE WALL, AN OPENING IN THE SIDE WALL AFFORDING ACCESS TO THE JUNCTION BOX, A CLOSURE FOR SAID OPENING, A HEAT BAFFLE PLATE CARRIED BY SAID CLOSURE IN SUCH SPACED RELATION AS TO EXTEND BETWEEN SAID PAIR OF BOX WALLS AT THE EDGE PORTIONS THEREOF ADJACENT THE HOUSING TO DEFINE A SUBSTANTIALLY CLOSED COMPARTMENT IN SAID JUNCTION BOX AND AN OPEN SPACE BETWEEN SAID COMPARTMENT AND THE HOUSING, SAID CLOSURE COMPRISING A PAIR OF PARALLEL PLATE MEMBERS CONNECTED ALONG ONE PAIR OF ADJACENT EDGES, ONE OF SAID PLATE MEMBERS BEING SECURED TO SAID HOUSING SIDE WALL AND EXTENDING OVER SAID OPENING AND THE OTHER BEING SPACED FROM THE HOUSING, AN ELECTRICAL SOCKET MOUNTED ON THE OTHER PLATE MEMBER, A CONCAVE REFLECTOR IN THE HOUSING EXTENDING OVER THE SOCKET, AND HEAT-INSULATING MEANS MOUNTING THE REFLECTOR IN THE HOUSING OUT OF CONTACT THEREWITH.