US2773153A

US2773153A - Temperature-responsive switch mounting and installation

Info

Publication number: US2773153A
Application number: US538140A
Authority: US
Inventors: Leo L Verkuil
Original assignee: Edwards Co Inc
Current assignee: Edwards Co Inc
Priority date: 1955-10-03
Filing date: 1955-10-03
Publication date: 1956-12-04
Anticipated expiration: 1973-12-04

Description

Dec. 4, 1956 1 L. vERKulL 2,773,153

TEMPERATURE-RESPONSIVE SWITCH MOUNTING AND INSTALLATION Filed Oct. 3, 1955 2 Sheets-Sheet 1 A al; TS

5 la Ts C f 0 l 26 t* f2 2 0 53 3l cn Bmetullc ATTORNEY Dec. 4, 1956 1 1 VERKUH. 2,773,153

TEMPERATURE-RESPONSIVE SWITCH MOUNTING AND INSTALLATION Filed Oct. 3, 1955 2 Sheets-Sheet 2 FIG@ INSULATION 4425 I |2356 Noi?? 21 |38 I7V V j |o l i 52 27C |l Il 28 52 FIG INVNToR. Leo L..Verkui| 19A/mmm ATTORNEY United States Patent TEMPERATURE-RESPONSKVE SWITCH MOUNT- ENG AND INSTALLATION Leo L. Verkuii, Norwalk, Conn., assigner to Edwards Company, Inc., Norwalk, Conn., a corporation of Flew York Application October 3, 1955, Serial No. 538,14@

S Claims. (Cl. 20G-138) This invention relates to the housing, mounting and installaltion of temperature-responsive elec-tric switches` particularly such as are to form part of re alarm or detector circuits or systems for the interiors of buildings, houses, and the like,

ln such systems, thermostatic switches, in suitable number, are installed at suitably distributed locations and are suitably interconnected electrically to a suitable alarm or signal-transmitting device which is caused to be actuated when any one or more of the thermostatic switches responds to rise in temperature, in the building karea `or space in which it is located, sufficient lto actuate the switch; such switches are usually located at or near the ceiling and usually are constructed or set to have different temperature-responsive ratings, such las 140 F., 180 F., or 200 F., for in some interior locations la switch of higher temperature response is appropriately employed while other spaces require switches of lower temperature response. Also, the circuits of such -systems are operable, according to circumstances, at different supply vvoltages, usually derived from the building or house lighting circuit and, ywhere the latter is an alternating current circuit, `a step-down transformer is usually employed to obtain the desired voltage for which the particular system is constructed or rated.

One of the objects of this invention is to provide a thermostatic switch and housing that will be of compact and reliable construction and `assembly and well adapted for ease `and facility of installation, as in re detecting systems of the abovementioned character. Another object is to provide a simple and practical thermostatic switch and housing or mounting therefor having coacting features of construction to facilitate manufacture and assembly and that will facilitate, in uncomplicated rnanner, installation according to various needs or requirements met with.

Another object is to provide a thermostatic switch mounting and installation capable of wide `and dependable flexibility of rearrangement or assembly, in the eld, to meet various types or standards of wiring, such as lowvoltage exposed wirng, surface wiring such `as armored, sheathed, or conduit-contained wiring, concealed wiring of the just-mentioned types, and the like. Another object is to provide a thermostatic switch mounting and installation capable of such flexibility of rearrangement or assembly, in the held, `so that, according to need, the thermostatic switch and mounting may be direc-tly surfaceinstalled as on a :ceiling or a wall, or assembled interiorly of a `wall box particularly where hush-mounting is desired or required, or assembled exteriorly of a -wall box or outlet box, all in va manner to meet the safety requirements or standards particularly Vith respect to various magnitudes of voltage of the circuit of the detector system. Another object is to provide a construction of the justmentioned character in ywhich dependable provision is made for maintaining visible, for whatever rearrangement or assembly of the parts is effected, suitable indicia rice identifying the technical lrating or other data as is or may be required, in systems of `the above-mentioned character, -by such lauthorities as the Board of Fire Underwriters.

Another object is to provide a thermostatic switch and housing of nonmetallic material and a mounting therefor of metallic material coactingly adapted for flexibility of assembly in various interrelationships -according to need while maintaining suitable safety factors of insulation and the like for lthe resultant assemblage and `the wiring leading therethrough to the thermostatic switch.

Another object is to provide a thermostatic switch subassembly adapted for direct installation with its thermostatic element presented for thermal response and an outlet box element to form therewith an assemblage with the `sub-'assembly selectively either within the box or outside of the box and in either case with the thermostatic element lproperly presented for thermal response Ifrom the outside of the box. Another object is to carry out the just-mentioned object in which the several parts are adapted for selective coaction, according tothe method of assembly, to provide safety of wiring to the switch.

Another object `is in general to provide improved constructions and installations of thermostatic switches, particularly to meet the diverse requirements of various kinds and types of wiring, in fire detector systems of the above-mentioned type, for bo-th existing building structures and structures in course of construction. Other objects `will be in part obvious or in part pointed out hereafter.

The invention accordingly consists `in the features of construction, combinations of elements, and arrangements of parts as will be exemplied in the structure `to be hereinafter described and the scope `of the applica-tion of ywhich will be indicated inthe following claims.

In the accompanying drawings in which a preferred embodiment of the invention is shown by way of lllustration and in which similar reference characters refer to similar parts throughout the several views,

Figure l is an elevation, as seen looking upward, of a `thermostatic switch and housing sub-assembly as it appears when installed, as on a ceiling or over-head beam or the like;

Figure 2 is an end elevation `as seen along the line 2 2 of Figure l;

Figure 3 is a vertical sectional View, on an enlarged scale, as -seen along the line 3-3 of Figure l;

Figure 4 is an elevation, as seen looking upward, of `an installation in which the sub-assembly -of thermostatic switch and housing and a plate element of a wall box yare arranged and coact for substantially concealed mounting with the thermally-responsive element of the thermostatic switch positioned substantially tlush with the plane of the ceiling;

Figure 5 is a transverse sectional View, on an enlarged scale and with certain parts broken `away `to conserve space, as seen `along the line 5-5 of Figure 4;

Figure 6 is an elevation, as seen looking upward, of Ian installation in which the thermostatic switch and housing sub-assembly and the plate element of the outlet box are rearranged and for wiring and mounting with the sub-assembly external of the wall box;

Figure 7 is a transverse section, on an enlarged scale and with certain parts broken `away to lconserve space, `as vseen lalong the line 7--7 of Figure 6, illustrating also that the wall box may be surface-mounted;

yFigure 8 is an elevation as seen along 'the line 8--8 of =Figure 2, showing in rear `elevation certain parts of the sub-assembly and, partially broken away, an insulating rear terminal cover plate; and

Figure 9 is an elevation of the rear terminal cover plate alone.

While, so far as other features of my invention are con cerned, the thermostatic switch may take other forms than that described, it preferably is constructed in the form of a compact unit adapted for easy assembly to other parts and provided with a thermally-responsive element that is birnetallic and preferably in the form of a concaveconvex bimetallic snap-acting disk so vas to present a suitable area thereof for thermal response to the atmosphere of the building space or room in which it is to be installed in a tire detection or alarm system. In the drawings, I have designated this preferred form of thermostatic switch unit, as a Whole, by the reference character TS, and its construction in general is better shown in Figures 3 and 8.

Turning rst to Figure 3, the thermostatic switch unit TS comprises 'a cup-like casing l0 of insulating material, such as lany of the moldable plastics, of round cross-section provided at its open end with an external tiange l1 and having seated across its open end the snap-acting bimetallic disk l2 which is secured in position by a metallic ferrule spun over the flange ll and the peripheral portion of the disk l2. As shown in Figure 3, the bimetallic disk 12 may be constructed, or assembled to the casing l0, so that in its normal bowed condition or shape, its convexity is toward the bottom end of the casing llt) and, upon rise in temperature, it reverses its bowed shape, doing so with a snap action as above mentioned.

Such bimetallic disks are well-known as are also various contact-making and contact-breaking arrangements to respond to this snap action for making or breaking the electrical circuit in which the thermostatic switch is connected; accordingly, any such suitable arrangement may be embodied within the cup-like casing l for co-action with the bimetallic disk l2 and need not be shown or described in detail. In Figure 3 l have therefore simply indicated such an internal circuit maker or breaker by the broken-line rectangle 14, its parts being electrically connected, in known manner, to two terminal and mounting lugs -5 of at sheet-metal stock set into and suitably secured at the external face of the bottom of the molded casing l0 (see also Figure 8) so that they project on a diameter and in opposite directions from the casing l0, being provided, in their projecting portions each with a Suitable hole for coaction with mounting and connecting screws `as later described.

The parts thus far described comprise the illustrative form which the thermostatic switch unit TS preferably takes; it may be embodied in dimensionally small and compact form. For example, the bimetallic disk l2 may have a diameter on the order of The thermostatic element illustratively in the form of bimetallic disk 12, may be constructed or set, in Icoaction with the internal switching mechanism 14, to have any suitable temperature-responsive rating, such as 140 F., 180 F., or 200 F., and in the tire detection system in which these thermostatic switch units are to be installed, the system can oftentimes include units of different temperature responses according to the different character of the respective rooms or spaces or areas, of the building, in which they are located. It is desirable, therefore, that the respective ratings, and other technical information, pertinent to each installed unit be always visible, even though the type or form of electrical wiring or of installation of the unit vary widely, within authorized standards, and thus also dependably comply with requirements for visible identifying and rating data.

In old as well as in new building construction, various types or standards of wiring are permissible, a factor of consideration including the voltage at which the tire detection circuit or system is to operate. For example, in a low-voltage system, on the order of 2S volts, the thermostatic switch unit, such as the unit TS, may be surfacemounted, as by mounting it on the ceiling or other overhead structure, and the circuit conductors, appropriately insulated for such lower voltages, may be run along and secured to similar surfaces. On the other hand, where the detector circuit is to operate at higher voltages, or for other reasons, the thermostatic switch unit is to be associated with a wall box, outlet box, or the like, with associated standards of wiring, and the box may be surfacemounted or flush-mounted, and in either case the thermostatic switch unit may, for various reasons, be mounted externally of the box or internally thereof. These varying conditions illustrate some of the variables met with in building structures, old or new or under construction, in installing tire alarm or detector systems, and one of the dominant aims of this invention is to provide practical and simple means for safety and dependably meeting such varying requirements.

in Figures 4 and 5 and Figures 6 and 7 I have shown two of several possible forms of installation requiring the use of a box, such as an outlet box, wall box, or the like, with which, for mounting and wiring purposes, the thermally-responsive switch, for re detection, is to be associated, thus also to facilitate the use of such kinds or standards of house wiring or building wiring as may be desired or needed. The latter are available in various forms of construction, such as non-metallic sheathed cable or conductor, metallic sheathed conductor, conduitcarried wires, and others, and for that reason such types of wiring are not shown in the drawings. The box shown in Figures 5 and 7 is generally indicated by the reference character B and may make any suitable or desired form of which also many are known; for purposes of illustration, the box B may comprise a standard type of outlet box having a usually flat bottom 17 and integral side wall 18 which may be circular or polygonal in cross-section, being provided with threaded inwardly projecting diametrically opposed lugs 20--20 (Figures 5 and 7) and screws 21-21. As is usual, the bottom 17 or the side wall 18 or both is provided with knock-outs 22 through which, when removed, the circuit wiring is brought into the box, in the manner known in the art.

To meet varying requirements such as those indicated above, I provide a number of parts that are assembled or may be assembled in various coacting relationships, and these include a housing generally indicated by the reference character H (Figures 2, 3, 5, 6, 7 and 8) to which the thermostatic switch unit TS is initially assembled to form a sub-assembly and a mounting plate generally indicated by the reference character MP (Figures 4, 5, 6 and 7) with which the housing and switch sub-assembly is coactingly and selectively assembled and which can also serve as a cover or closure plate for the box B (Figures 4-7), being peripherally shaped, illustratively circular, to suit the shape or open end of the box, being provided with sutiable means such as the diametrically opposed slot 24!- aud keyhole 25 (Figures 4 and 6) for coaction with the screws 21-21 to secure it in position as a closing wall of the box B. The mounting plate MP is of suitably heavy metal, conveniently in the form of a stamping, and at a suitable location therein, preferably at its center, it is provided with a relatively large opening O, which may conveniently be punched therein in stamping out the plate itself and which is round or circular and of 'a diameter materially greater than the outside diameter of the thermostatic disk assembly (see Figure 3), that being the outside diameter of the ferrule i3. Along `the line of the diameter of central'v opening O and as is better shown in Figures 4, 5 and 7, I provide, equally spaced from the opening O, threaded screw-receiving holes Zei-26.

The housing H (Figures l, 2, 3, 5, 6 and 8) is in the form of a molding of cured plastic and hence insulating material and I provide it with a front Wall 27 that is externally ila-t and which, at its center, has a round opening 28 (Figures 3 and 5) of a diameter slightly greater that the diameter of the ferrule i3 of the bimetallic disk assembly and, surrounding opening 28, is molded a collar C that projects from the front wall 27 by an amount about equal to the thickness of the mounting plate MP s and that has substantial thicknessor radial dimension to provide a large annular front face upon which, as'by printing or molding, is carried and displayed suitable identifying or rating data as is diagrammatically indicated at 3i in Figures l, 4 and 6. The outside diameter of collar C is such that the collar is relatively freely receivable into the opening O (see Figures 4 and 5) of the mounting plate MP with the hat front wall 27 of housing H resting atwise and well seated against a face of the mounting plate MF.

As better shown in Figures 3 and 8, there are molded integrally with the front wall 27 two relatively short pro- 'ections or pillars .3d-34 closely adjacent the round Wall opening 2S and aligned along the line of the diameter of the latter; the sho-rt posts 3ft-34 provide inner flat faces against which the opposed sheet-metal lugs 1515 of the thermostatic switch unit TS are brought to rest upon assembling the latter to the housing H by moving it toward the right in Figure 3, to enter the switch casing into the housing opening 28, bringing the unit TS to rest with the plane of the bimetallic disk 12 parallel of the front housing wall 27 but spaced forwardly therefrom and from the front annular face of the coll-ar C, somewhat as shown in Figure 3. The short posts 34-34 have molded into them the head ends of the two securing and connecting screws 36,-36 over the threaded ends of which the apertured connector lugs -15 take during the above described assembly movement, whereupon the lugs 15S-15 are clamped against the posts 34-34 by clamping nuts 37-37, thus securing the therrnostatic switch unit TS in assembled relation to the housing H. The free threaded ends of the screws 36-36 then receive suitable washers and nuts i3--4tl respectively, whereby circuit conductors may be mechanically secured and thereby the switch mechanism ifi connected electrically into the system circuit.

The housing H has a side w-all 42 (Figures 3 and 5) which can be of any suitable conguration preferably cylindrical (see Figure S), with its axis coincident with the axis of the front wall opening 23 (Figures 3 and 5) and it extends rearwardly (to the left, in Figure 3) to terminate in an annular edge face 43 the plane of which is hat so that the housing may rest well-seated against a face of the mounting plate MP as in Figure 7 or against some other flat supporting surface such as that of a wall or ceiling or beam, indicated at 44, as shown in Figures l and 2.

The side wall l2 of housing H extends beyond the plane of the ends of the terminal screws 36-36 by a substantial amount (see Figure 3), in order to provide ample space to removably receive a rear terminal cover plate TP of insulating material that is peripherally seated against a ledge provided by the side wall 42 in the form of a rabbet 45 molded into the annular edge face 43 (Figures 3 and 8). With the side wall 42 of annular cross-section, the rabbet 45 and the shoulders or ledge that it forms are also circular and accordingly the terminal plate TP is in the form of a disk of suitable insulating material, conveniently stamped out of flat stock, and in the course of so stamping it for peripheral reception in the rabbet 45, I also stamp out a central round hole 46 (Figures 3, 8 and 9) that is of materially smaller diameter than the opening O in the mounting plate MP as is better shown in Figure 7, and l also stamp or punch two smaller holes @f7-i7 (Figure 9) that are aligned on a diameter and equidistantly spaced from the center of the terminal plate TP.

Molded integrally with the front wall 27 of housing H (Figures 5, 7 and 8) and projecting rearwardly therefrom are two pillars 48-43 aligned on a diameter of the housing H, a diameter that is at a right-angle to the diameter on which the short posts 35i-34 and their respective mounting and connecting screws .S6-36 are aligned; the pillars i3-48 terminate in end faces that fall in the plane of the casing rear edge face 43 (see Figures 5 and 7), they are preferably of round cross-section, and at their rear ends they are stepped to terminate in smallerdiarnetered end portions which extend respectively into the smaller holes 47-47 of the terminal cover plate TP and whereby also the pillars provide annular ledges or seats 50-50 against which plate TP rests, coincidentally with its peripheral seating against the ledge of the rabbet 45 in the side wall 42, as is better shown in Figure 7.

In each of the pillars 48-48, there is molded a coaxial hole 51 of a diameter to freely receive a screw therethrough, the hole 51 terminating, at the front face of the front wall 27, in a larger diameter, like a counterbore, as at 52 so as to accommodate therein the head of a securing screw. The spacing, along the line of the diameter, of the axes of the long screw-receiving holes 51-51 is lthe same as the spacing, along the line of the diameter of the opening O in the mounting plate MP (see Figures 4, 5 and 7), of the threaded holes 26-26 in the mounting plate MP. To selectively and coactingly assemble the mounting plate MP and the sub-assembly of housing H and thermostatic switch unit TS, I provide two machine screws 53--53 (see Figures 5 and 7).

Referring now to Figure 7, let it be assumed that, to meet one type of wiring or installation requirement, a box B is required and that the sub-assembly of housing H and thermostatic switch unit TS have to be or can be accommodated externally of the box B. ln such case, the appropriate insulated conductors, of which two are fragmentarily shown in Figure 7 at W-, are first brought through the large central opening 0 in the mounting plate MP, either before or after securing the mounting plate iP in box-closing position by screws 21, the back terminal cover plate TP, detached from the housing H, is then snaked onto the conductors to pass them through the hole 46 which is smaller than the mounting plate opening O and their stripped ends or portions are then connected respectively, by the washers 33 and nuts 4G, to the screw connecting posts 36-36g housing H and insulating back plate TP are then brought together to seat the insulating plate in the peripheral wall rabbet 45 and against the annular shoulders or ledges Sti-S@ of the internal pillars iS-48 respectively, and the resultant assemblage is then brought against the front face of the mounting plate MP, substantially in the relationship shown in Figure 7; the machine screws 53-53 are then inserted through the long holes Sl-S in the pilla-rs, from the front wall 27 of the housing H, and their threaded ends engaged respectively with the threaded holes 26-26 of the mounting plate MP, thereby coaxially aligning the several coaxial parts of the sub-assembly with the center or axis of the large opening O in the mounting plate MP, the heads of the screws being accommodated in the recesses 52-52 so that they do not protrude from the out side face of the front wall 27 of housing H.

The clamping pressure exerted by the screws 53 is taken up by the relatively heavy and strong illars di! (see Figure 7), protecting the molded non-metallic housing H against distortion and the housing H is held wellseated against the front face of the metal mounting plate MP and the plane of the thermostatic disk element 12 is dependably positioned to face in the desired direction such as downwardly from a ceiling. Moreover, the rear insulating terminal cover plate T P, though not directly secured to the rear of the housing H, becomes dependably locked in piace to insulatingly close over the terminal connector screws and the respective wiring connections made thereat, thus providing an insulating barrier against the metal mounting plate MF, and the smaller hole te in the insulating plate TP becomes coaxially fixed relative to the larger opening O of the mounting plate MP, as is better shown in Figure 7, thus to provide a protective insulating ring for the opening O in the metal plate MP so that, for example, detrimental engagement of the insulated conductors W-l with the metal periphery of the opening O is guarded against. And the rating. identifying, or other data that appears on the front annular face of the collar C of the thermostatic switch unit TS becomes positioned, as appears better from Figure 6, where it is indicated diagrammatically at 31, where it is always opening visible.

in Figure 7 the box B is shown as surface-mounted, as by screws (not shown) or other suitable means, to the supporting surface of the building part designated by the reference character 4d, such as a ceiling, beam, or the like; it will be apparent, in View of the disclosure herein, that the box B of Figure 7 may also be flushmounted or recessed into the ceiling or like structure, and in either case, where it is desired or appropriate to install the housing and thermostatic switch sub-assembly H-TS externally of the box, the assemblage thereof to the mounting plate MP is like that shown in Figure 7 and may be proceeded with in the manner above described. However, in either case and particularly where the box B is flush-mounted, it may be desired or required that the sub-assembly be installed internally of the box, particularly where, from the viewpoint of appearance, less obtrusiveness is desired, and in such case the installation is effected by re-arrangement of parts as is il'lustratively now to be described.

Such a rearrangement and different type of installation is illustrated in Figures 4 and 5, where the box is shown recessed in the ceiling 44 or like support so that the plane of its open end is substanitally in the plane of the support. In this re-arrangement of the parts, the insulating back terminal cover plate TP is removed from the back of the housing7 H, and the latter, with the therinostatic switch unit TS assembled thereto to form the sub-assernbly as above described, is placed with its flat front wall 27 against the inside face of the mounting plate MP before the latter is secured to the box, positioning the parts so that the thick-walled collar C enters the opening in the mounting plate MP, thus permitting the flat front face of front wall 27 to be seated atwise against the mounting plate and thus also, because of the intertitting of collar C with the plate opening O. aligning the various parts of the sub-assembly as a unit with the axis of the plate opening O. Thereby, by simple relative rotational movement, the holes Sil-l of the internal pillars dii-4S are easily brought into respective alignment with the threaded holes 26-26 of the metal mounting plate MP, whereupon the two machine screws E53-53 are inserted into the pillar holes through the rear end faces of the pillars and the threaded ends of the screws are then threaded into thel threaded holes 26-26 respectively as shown in Figure 5, with the screw heads taking against the rear annular end faces of the pillars which take up the clamping pressures exerted by the screws, thus clamping and seating the front face of the front wall 27 of the housing H snugly against the inside face of the mounting plate MP, without detrimentally straining the housing H and the thermostatic switch ports carried thereby.

The circuit conductors (not shown) which can be like the conductors W-i of Figure 7, and which like the latter, are brought into the box according to the particular type of circuit wiring desired or required, are now connected to the terminal connector screws E56-36 which, with their clamping washers and nuts, are readily accessible through the rear open end of the housing H, because ot the absence of the rear insulating terminal cover plate TP. The resultant assemblage is now as a unit attached to the box E, via the screws 21-21 and the slots 24;--25 (see Figures 4 and 5) with the open-ended sub-assembly of thermostatic switch unit TS and housing H carried und positioned inside of the now covered or closed-over box E, except for the collar C and the bimetallic disk 12 and part of the securing ferrule 13 which extend within and slightly beyond the collar C, somewhat as shown in Figure 5. The plane of the front face of the mounting plate MP can be coincident with the surface of the plete installation.

ceiling 44 and both surfaces can be painted or finished oi so that one virtually merges into the other.

Only the bimetallic disk 12 and part of its securing ferrule 13 project somewhat beyond the outer face of "ie mounting plate MP and the bimetallic disk 12 is dependably positioned facing the area or space to the temperature of which it is to respond upon dangerous rise; surrounding it and the ferrule 13 is the non-metallic collar C of the housing H, being in effect interposed therebetween and the metal mounting plate MP to vir tuaily form a barrier against the drainage of heat away from the bimetallic disk by the surrounding mounting plate metal that has much greater mass and area, thus avoiding detrimental interference with the sensitiveness of temperature response of the bimetallic disk itself. At the saine time, the front annular and radially-wide face of the collar C is fixedly positioned and its identifying, rating, or other data 31 (see Figure 4) carried by it is dependably maintained visible at the front of the com- It will now be readily apparent, in view of the foregoing, that the installation just described, with the sub-assembly of thermostatic switch unit TS Iand housing H positioned inside of the box B, may be carried out with equal effectiveness in meeting various requirements or standards of safety wiring where the box B is surface-mounted as is the box B of Figure 7.

As earlier above noted, where the fire alarm or detection system operates at relatively low voltages, it is permissible to employ suitably insulated conductors that may be run along and secured to the exposed surfaces of ceilings, beams, or the like, and in such cases it is permissible to install the thermostatic switch unit on such surfaces without the intervention of special wiring accessories, such as outlet boxes or the like, as are required for higher-Voltage systems. ln such cases, I make provision in Athe housing H for mounting it, with its thereto assembled thermostatic switch unit TS, directly to and upon such surface and for ease and facility of leading the insulated wires to the interior of the housing and at the same time protectively insulating the ceiling or other surfaces from the interior terminal connectors and connections. As is better shown in Figure 3 and also in Figure S, I provide, by molding, two cut-outs S23- 55 in the side wall 42 of housing H and at diametrically 0pposed points therein along the line of the diameter along which are located the terminal screws Zio-36; these cutouts are open ended into the rear edge face 43 of the peripheral side wall 42 of the housing H.

By removing the insulating back cover plate TP, the circuit wires are readily connected to the terminal screws and then they are laid into either or both of the openended cut-outs 55, that being facilitated by the diametrical alignment (see Figure 8) of the cut-outs and terminal connectors and by the roominess within the housing H inasmuch as the pillars 4848 are located well to either side of such diametrical alignment of these parts and, as is better shown in Figure 3, the thermostatic switch casing 10 projects but slightly into the interior of housing H. For similar reason of roominess, it might be here noted, the electrical connections necessary in completing the other types of installations above described in connection with Figures 4 5 and Figures 6-7 are made with equal facility even though the parts are relatively small.

For direct surface-installation, having laid the insu lated wires in the cut-outs 555-55, the rear insulating terminal cover TP is put in place, being peripherally seated in the rabbet 45 only when the plate TP is rotatively positioned so that its two spaced small holes 47-47 (see Figure 9 and Figure 8) are coaxial with the pillars 3S-43 respectively to enter the smaller-diametered ends of the pillars 48-48 into the respective plate holes 417-47. Now, wood screws 56 are entered through the holes 51h51 of these pillars, through the front face of front wall 27, and with the back plate TP assembled as just described, it is not neces ary to have to manipulate the back plate to seek out holes or passages therein through which the screws are to pass. in this manner, the mounting of the sub-assembly directly to the surface of the ceiling or other support, indicated at 44 in Figures l, 2 and 3, is readily completed with the driving home of the screws Se Se, the heads of which enter the recesses at the outer ends of the pillar holes Si and thereby the housing H is securely clamped to the supporting surface, with the otherwise unsecured insulating bachr plate 'P locked in closing position and safely insulating the terminal connectors and electrical connections thereat from the supporting surface dei. The screw clamping stresses are taken up primarily by the relatively heavy pillars ifi-d3 without detrimentally straining the non-metallic insulating housing H.

The bimetallic disk element it?. is thus dependa-bly installed and positioned in relation to the room or to the temperature of which it is to respond upon dangerous rise; the collar C, surrounding it with its broad annular front face, maintains visible the desired or required identifying, rating or other data thereon, indicated at 31 in Figure l, in this type of direct-surface installation.

It will be seen that there has been provided in this invention, a temperature-responsive electric switch and housing, mounting and installation in which the several objects hereinabove set forth, together with many theroughly practical advantages, are successfully achieved. It will be seen that the constructions are capable of ease of fabrication and provide wide and dependable llexibility of assembly, in the held, to reliably meet varying conditions and requirements met with particularly in the wiring and installation of tire alarm or detector systems in the various types of house or building construction met with.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinabove set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

l. A thermostatic switch mounting means comprising a mounting plate having a relatively large round opening therein with threaded screw holes spaced therefrom and adapted to form a closure for an outlet box, a housing of insulating material having a front wall provided with an aperture surrounded by a collar, said collar having an outside diameter so that it is receivable in said mounting plate opening, a thermostatic switch structure supported within said housing and having a part comprising a bimetallic disk positioned to substantially close ott said aperture at said collar, said switch structure having ter minal connectors within said housing, said housing having a peripheral side wall and a rear closure plate ot' insulating material and removably associated therewith, said rear closure plate having a relatively large round opening therein that is smaller than the opening in said mounting plate and that is coaxial with said collar, said housing and rear closure plate having means forming spaced screw passages of the same spacing as the threaded holes in said mounting plate, and threaded screws to extend through said passages for threading into said threaded holes from the rear end of said housing with the tro-nt wall of the latter resting against the inside face ot said mounting plate and said collar received in the mounting plate opening or from the front wall with said rear closure plate resting against the outside face of said mounting plate and with the smaller opening in said insulating rear closing plate substantially coaxial with the larger opening in said mounting plate to substantially peripherally insulate the latter opening for the passage of connecting conductors therethrough to said connecting terminals.

2. A thermostatic switch mounting means comprising a mounting plate having a relatively large round opening therein with threaded screw holes spaced therefrom and adapted to form a closure for .an outlet box, a housing of insulating material having a front wall provided with an aperture surrounded by a collar, said collar having an outside diameter so that it is receivable in said mounting plate opening, a thermostatic switch structure supportedwithin said housing and having a part comprising a bimetallic disk positioned to substantially close olf said aperture at said collar, said switch structure having terminal connectors within said housing, said housing having peripheral side walls terminating in a rabbeted rear edge face and said front wall having spaced hollow pillars extending rearwardly therefrom and terminating in the plane of said rear edge face, a rear cover plate of insulating material peripherally seated removably in the rabbet ot said rear edge face and having cut-outs to clear said hollow pillars, said cover plate having a round opening smaller than that of said mounting plate and coaxial with said collar, and threaded screws for threaded engagement with said spaced threaded holes in the mounting plate upon passage of the screws from the rear ends 0f said pillars with the front wall resting against the inside face of said mounting plate and said collar entered into said mounting plate opening or for passage into said pillars from the front wall of the housing with said rear edge face and insulating rear cover plate resting against the outside face of the mounting plate with said two plate openings substantially coaxial so that the mounting plate opening is peripherally insulatingly overlapped.

3. A thermostatic switch mounting means comprising a mounting plate having a relatively large round opening therein with threaded screw holes spaced therefrom and adapted to form a closure 'for an outlet box, a housing of insulating material having a front wall provided with an aperture surrounded by a collar, said collar having an outside diameter dimensioned so that it is receivable in said mounting plate opening, a thermostatic switch `structure supported from within said housing and extending into the space encompassed by said collar and positioning to the exterior of said space a thermally-responsive element, said switch structure having terminal connectors underlying said front wall at the side of said aperture, said housing having peripheral shallow side walls Iterminating in a rear edge face and said front wall having spaced hollow pillars of the same spacing as said threaded holes and extending rearwardly and terminating in lthe plane of said rear edge face, said side walls and said pillars having ledges that lie internally of said plane, a rear `cover plate of insulating material seated removably at said ledges of said side walls and having spaced holes to receive the rear-ends of said pillars up to the ledges of the latter, said cover plate having a round opening smaller than that of said mounting plate and coaxial with said collar, and threaded screws for threaded engagement with said spaced threaded holes in the mounting plate upon passage of the screws from the rear ends of said hollow pillars with the front wall resting against -the inside face ot' said mounting plate and said collar entered into said mounting plate opening or for passage into said pillars from the front Wall of the housing with said rear edge face and the rear ends of said pillars resting against the outside face of the mounting plate with the insulating cover plate between said outside face and said ledges and said two plate openings substantially coaxial so that the mounting plate opening is peripherally insulatingly overlapped.

4. A thermostatic switch and housing means for selective mounting by a mounting plate that has a relatively large round opening therein with threaded screw holes spaced ytherefrom and adapted to form a closure for an outlet box, said means comprising a housing of insulating material having a front wall provided with a round aperture surrounded by a collar of substantial radial dimension and presenting a relatively large annular front face for identifying rating indicia, a thermostatic switch structure supported from within said housing and extending into the space encompassed by said collar and positioning to the exterior a bimetallic disc corresponding to said rating indicia, said switch structure having terminal connectors within said housing, said housing having a peripheral side wall and a rear `cover plate of insulating material removably associated therewith, said rear cover plat-e having a relatively large round lopening therein that is coaxial wi-th said collar, said housing and rear closure plate having means forming spaced screw passages from front to rear for the passage therethrough of mounting screws and whereby threaded screws may be extended through said passages for threading into said threaded holes from the rear of said housing with the front wall of the latter resting against the inside face of said mounting plate and said collar with its rating indicia received in the mounting plate opening and the indicia maintained` visible or said screws extended therethrough from 'the fron-t wall with said rear cover plate adjacent the outside face of said mounting plate and wi-th the opening in said insulating rear cover plate substantially coaxial with the opening in said mounting plate for `the passage of connecting conductors therethrough to said connecting termin-als.

5. A thermostatic switch and housing means for selective surface mounting or mounting by a mounting plate that. has a relatively large round opening therein with threaded screw holes spaced therefrom and adapted to form a closure for an outlet box, said means comprising a housing of insulating material having a front wall provided with a round aperture surrounded by a collar of substantial radial dimension and presenting `a relatively large annular front face for identifying rating indicia, a thermostatic switch structure supported from within said housing and extending into lthe space encompassed by said collar `and positioning to the exterior a bimetallic disc corresponding to said rating indicia, said switch structure having terminal connectors within said housing, said housing 'having a peripheral side wall and a rear cover plate of insulating material removably associated therewith, said housing and rear closure plate having means forming spaced screw passages from front to rear for the passage therethrough of mounting screws and whereby threaded screws may be extended through said passages for threading into said threaded holes from the rear of said housing with the front wall of the latter resting against the inside face of said mounting plate and said collar with its rating indicia received in the mounting plate 'opening and the indicia maintained visible or screws may be extended therethrough from the front wall with said rear cover plate adjacent the surface of a support and locked between the latter and the housing upon threading the screws into said support and said collar and rating indicia thereby `faced forwardly of said supporting surface.

6. A thermostatic switch and housing means for selective surface mounting or mounting by a mounting plate that has a relatively large round opening therein with threaded screw holes spaced about a circle yconcentric with said opening, said plate being adapted to form a closure for an outlet box, said means comprising a housing of insulating material having a front wall provided with a round aperture of materially smaller diameter ythan that oi' said plate opening and bearing identifying rating indicia within an exterior `annular area about the aperture of radial dimension not greater than the difference in the radii of said opening and aperture, a thermostatic switch structure supported from within said housing and extending into said round aperture and positioning to the exterior of the housing and coaxially with said annular area a bimetallic disc corresponding to said rating indicia, said switch structure terminal connectors Within said l'tousing, said housing having a peripheral side wall and a rear cover plate of insulating material removably associated therewith, said housing and rear closure plate having means forming screw passages from front to rear for the passage therethrough of mounting screws, said screw passages being spaced about a circle concentric with said annular indicia-bearing area and of the same diameter as the circular of spacing of said threaded screw holes of the mounting plate, whereby threaded screws may be extended lthrough said passages for threading into said threaded holes from the rear of said housing with the front wall of the latter resting against the inside face of said mounting plate and said annular indicia-bearing area located coaxially with the mounting plate opening to fall within the projected area of |the latter and the indicia maintained visible or screws may be extended therethrough from the front Wall with said rear cover plate adjacent the surface of a support and locked between the latter and the housing upon threading the screws into said support and said annular area and rating indicia thereby faced forwardly of said supporting surface.

7. A thermostatic switch and housing means comprising a housing of insulating material having a front wall provided with an aperture surrounded by an external collar of relatively substantial radial and axial extent, a thermostatic switch structure supported from within said housing and extending into the space encompassed by said collar and positioning to the exterior of said space a thermally-responsive element, said switch structure having terminal connectors underlying said front wall at the side of said aperture, said housing having peripheral shallow side walls terminating in a rear edge face and said front wall having spaced hollow pillars extending rearwardly and terminating in the plane of said rear edge face, said side walls and said pillars having ledges that lie inwardly of said plane, a rear cover plate of insulating material seated removably at said ledges of said side walls and having spaced holes to receive the rear ends of said pillars up to the ledges of the latter, said rear cover plate having a round opening that is coaxial with said collar, and threaded screws for passage through said hollow pillars to secure said housing to a support and adapted when passed into said pillars from the front of the housing with the rear ends of said pillars resting against a supporting surface to clamp the pillars against the latter `with the insulating cover plate locked between said supporting surface and said ledges.

8. A thermostatic switch and housing means comprising a housing of insulating material having a front wall provided with a central round aperture with two connector screws depending interiorly from diametrically opposed short posts formed in said wall, a thermostatic switch structure extending into said aperture and positioning to the exterior of said housing a thermally-responsive element, said switch structure having diametrically opposed connector lugs underlying said front wall and respectively secured to said screws, said housing having a peripheral cylindrical side wall terminating in a rear edge face and said front wall having two hollow pillars spaced on a diameter making an angle to the diameter on which lie said spaced connector screws, said pillars extending rearwardly and terminating in the plane of said rear edge face, said side wall having ledges that lie inwardly of said plane, a disk-like rear cover plate of insulating material seated removably at said ledges of said wall and having spaced holes to receive the rear ends of said pillars whereby said cover plate cannot be seated at said ledges unless it is rotatively oriented to enter the pillar ends in its holes, and threaded screws for passage through said hollow pillars to secure said housing to a support and adapted when passed into said pillars from the front of the housing with the rear ends of said pillars resting against a supporting surface to clamp the pillars against the latter with the insulating cover plate locked between said supporting surface and said ledges.

No references cited.