Non-Metallic Electrical Box With Metallic Fixture Support

The present invention relates to electrical boxes and methods of producing the same.

Consumers, updated National Electrical Codes (NEC), and Underwriter Laboratories (UL) requirements all require that electrical boxes be made stronger than in the prior art.

An object of the invention is to overcome the drawbacks of known electrical boxes.

A further object of the invention includes making electrical boxes which use the standard punched-out, stamped electrical boxes in a more intelligent fashion.

Yet another object of the invention is to take out the radius of a standard industry size electrical box so that a support for supporting a fixture can be located the proper distance from a second support to meet National Electrical Code (NEC) standards.

Another object of the invention is to eliminate the problem of pure plastic boxes being unusable for heavy-duty use.

Another object of the invention is to achieve a strengthened electrical box with a supplemental support within a standard so-called "4.times.4" box, while maintaining the near universal 3.5 inch (8.9 cm) spacing between the fixture supports so that the box is usable with standard light fixtures, ceiling fans, and the like.

It is likewise an object of the invention to provide metal supplemental supports in non-metallic and/or plastic electrical boxes to enhance the carrying strength of the electrical boxes.

Yet another object of the invention is to provide studs in the electrical boxes which cover the threads of standard screws so that no screw threads are present in the interior of such electrical boxes.

A still further object of the invention is to provide an electrical box having a sufficiently smooth interior for preventing wear to the plastic coating of plastic-coated electrical wire.

It is yet another object of the invention to provide electrical boxes in which added supports, such as studs, are added during the manufacturing process to eliminate problems in prior art electrical boxes, as well as to strengthen the inventive electrical boxes.

Another object of the invention is to provide a junction box having a supplemental support, yet which requires no welding during assembly thereof.

Yet another object of the invention is to provide an electrical box having components which are easily fabricated, added to the electrical box, and assembled in the final form by the operation of screwing or riveting, yet which do not loosen when subjected to static and/or dynamic loading.

A still further object of the invention is to provide a plastic junction box having metal components that is a "marriage" of plastic and metal and which enhances and exploits the properties of both materials.

A still further object of the invention is to provide a junction box capable of carrying static and/or dynamic loads having an auxiliary support and that is assembled with fewer parts and with fewer steps than known devices.

It is a yet further object that all the above be carried out with an electrical box which carries the static and dynamic load of supported fixtures better than known electrical boxes.

It is another object of the invention to provide a junction box which is made of plastic, yet which is self-grounded.

It is a still further object of the invention to maximize the use of non-metallic materials in a junction box, while minimizing the use of metallic materials in junction boxes.

A still further object of the invention is to provide a plastic junction box which can support both light fixtures and ceiling fans.

In summary, the present invention is directed to an electrical junction box or mounting assembly having a top wall and a side wall. The side wall extends downwardly away from the top wall and defines a cavity therein. A hole is provided in the side wall, and a fixture support is disposed in the hole. A threaded hole is provided on the fixture support, and the threaded hole is sized for mating with the threads of a fixture fastener. The fastener may be a screw. The fixture support may be made of metal, and the side wall and/or top wall may be made of plastic. The fastener may be a stud having the threaded hole therein. Flutes may be provided on the stud for engaging with the plastic/metal side wall for preventing rotation of the stud. An adhesive sufficiently strong to adhere the junction box to a downwardly facing surface may be provided on the top wall of the junction box. The adhesive may be in the form of double-sided tape.

These objects and advantages as well as others will be readily apparent from a review of the following description and drawings.

The drawings show a variety of embodiments of the invention, as will be clear from reading the description below.

It is important to note that the use of relative terms such as "up" and "down", and "left" and "right" is for convenience only and is not intended to be limiting.

FIG. 1 is a cross sectional view of a PRIOR ART electrical junction box having an inwardly extending ear E with a face plate attachment hole F provided therein;

FIG. 2 is a perspective view of a preferred embodiment of an electrical junction box according to the invention showing the use of a fluted support on the junction box;

FIG. 3 is a perspective view of the support of FIG. 2;

FIG. 4 is a perspective view of another preferred embodiment of a support according to the invention;

FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 4;

FIG. 6 is a perspective view of another preferred embodiment of a box according to the invention;

FIG. 7 is a perspective view of yet another preferred embodiment of a box according to the invention;

FIG. 8 is a perspective view of another preferred embodiment of a junction box according to the invention;

FIG. 9 is a perspective view of yet another preferred embodiment of a junction box according to the invention;

FIG. 10 is a perspective view of another preferred embodiment of a box according to the invention;

FIG. 11 is a cross-sectional view of FIG. 10;

FIG. 12 is a cross-sectional view, similar to FIG. 11, of a further preferred embodiment of the invention; and

FIG. 13 is a perspective, exploded view of a further preferred embodiment of a junction box according to the invention;

FIG. 14 is a bottom view of FIG. 13;

FIG. 15 is a perspective, exploded view of another junction box according to the invention;

FIG. 16 is a perspective, exploded view of a further junction box according to the invention;

FIG. 16A illustrates an optional grounding plate for use with the junction box of FIG. 16;

FIG. 17 is a perspective, exploded view, taken from below, of yet another preferred embodiment of a box according to the invention; and

FIG. 18 is a perspective, exploded view of a junction box according to yet another preferred embodiment of the invention.

FIG. 1 shows a PRIOR ART junction box including a side wall S, an upper wall U, and an ear E extending from a lower portion L thereof.

Upper wall U has one or more attachment holes A through which fasteners will be inserted for attaching PRIOR ART electrical box B to an overhead surface, such as to a ceiling joist or piece of plywood extending therebetween.

A lower, faceplate attachment hole F is typically provided in inwardly extending ear E. Frequently, faceplate hole F is provided with threads for mating with respective faceplate fasteners when securing an unillustrated faceplate thereto. Such faceplates are used to enclose electrical box B after the wiring inside the electrical box/junction box B has been completed.

A drawback of such PRIOR ART electrical boxes B is that they are typically made with stamped sheet metal extensions E; consequently, extensions E are relatively thin (i.e., in the order of about 1 millimeter or less). Such extension or ear E has a width of only a few millimeters, and only extends several millimeters inside box B. Thus, the surface area of ear E, when viewed from below after installation of upper wall U against a typical horizontal ceiling, is often substantially less than one centimeter squared (1 cm.sup.2)

Consequently, ear E may only carry relatively small vertical loads, when installed against the ceiling, as described above.

As a result, local codes frequently allow such PRIOR ART boxes B to be used only for supporting the weight of a faceplate, or of a relatively light static load, such as a small light fixture.

Such electrical boxes B are unsuited for supporting large static loads, as well as for supporting large dynamic loads, such as ceiling fans which may weigh twenty-five kilograms or more (25 kg).

Thus, there is a need for an electrical box which is suited for carrying relatively large static loads as well as dynamic loads.

That need is especially clear, given that many homeowners want to install heavier light fixtures and dynamic loads, such as ceiling fans, than had exhibited such preferences in the past.

Furthermore, even if the initial owner/builder of a house or commercial space provides PRIOR ART load-carrying junction boxes B suited for carrying the vertical force of a small light fixture, a subsequent owner/user will often replace the original light fixture with a heavier light fixture, or with a dynamic load; i.e. a ceiling fan.

Accordingly, there is a need for a load-carrying junction box which is suited for a wide range of static and dynamic loads and, thus, suited for original installation in new construction, given that some users fail to upgrade load-carrying junction boxes when adding heavier static and/or dynamic loads to the box.

The electrical box according to the invention has overcome these drawbacks described immediately above, and has achieved the objects of the invention detailed above. Such will be evident when reading the following detailed description of the invention.

Turning to FIGS. 2-3, a first preferred embodiment of an electrical box and/or junction box 10 according to the invention will now be described in detail.

Junction box 10 includes a top wall 14, and a side wall 18 extending downwardly therefrom and defining a cavity therein.

One or more hole 22 are provided in top wall 14 through which a fastener, such as a screw or nail, is inserted for securing junction box 10 to the support surface, such as a wall or the downwardly facing lower face of a ceiling joist.

Box 10 may have an extension 30 attached to and extending away from side wall 18. Extension 30 may extend inwardly (as shown) or outwardly away from the outer face of side wall 18, depending on the intended use.

A hole 32 is provided in box 10. Preferably, hole 32 is formed in side wall 18. Most preferably, hole 32 extends through extension 32, for enhancing the overall load capacity for carrying electrical fixtures, such as lights and ceiling fans, as will be appreciated more fully from reading the following.

Hole 32/extension 30 includes an upper edge/portion 34, suited for engaging a fixture support 40.

Fixture support 40 includes a shaft 42, a head 46 and fluting or raised surface or roughened surface 48 thereon. When fixture support 40 is secured in hole 30 and, hence, relative to the remainder of junction box 10, fluting 48 preferably engages upper portion 34 for resisting rotation of fixture support 40 about its longitudinal axis. Such resistance to rotation is particularly important when fixture support 40 carries a ceiling fan attached thereto by use of ceiling fan fasteners 49 engaged with internal threads 44. Such resistance to movement/rotation of fixture support 40 reduces the possibility that the connection between ceiling fan fasteners and junction box 100 occur. Such loosening has been known to occur in prior art devices, especially given the prevalence of reversible ceiling fans, and even when non-reversible ceiling fans have been attached, owing simply to the high static and dynamic loading of ceiling fans acting on prior art ceiling fan fasteners and prior art supports.

Fluting 48 is also useful to ensure that fixture support 40 remains in place during production, packaging, shipping and marketing thereof.

Fluting 48 may be provided at a different location on fixture support 40 other than as shown, at multiple locations, or along the entire length of shaft 42.

FIG. 4 illustrates another preferred embodiment of a junction box 50 according to the invention.

Junction box 50 includes an extension 60 having a hole 62 therein. Hole 62/extension 60 includes an upper edge/portion 64, such as the illustrated stepped square portion 64.

A fixture support 70 is similar to fixture support 40, except that a substantially square head 76 is provided thereon.

Stepped, square portion 64 is preferably configured to mate with head 76 of fixture support 70. Stepped, square portion 64 may be formed sufficiently deep so that head 76 does not protrude above the outer surface of top wall 14, when support 70 is installed.

It will be appreciated that square head 76 is particularly useful for intended uses in which the expected loading would be greater than the typical rotational loading/forces to which fluting 48 alone would be subjected.

Needless to say, head 76, and head 46 of the embodiment of FIGS. 2-3, both serve to prevent fixture support 70 and 40, respectively, from being pulled away from the remainder of boxes 50 and 10, such as by increasing the surface area over which such downwardly exerted forces are spread over box 10 by such forces acting on fixture fasteners 49 secured in internal threads 44.

FIG. 5 illustrates additional detail of fluting 48 on shaft 42 of fixture supports 40 and 70 of FIGS. 2-4, respectively. Typically, about 1-14 flutes will be provided on shaft 44 having an outside diameter (O.D.) of 0.25 inches. It is contemplated that 15 flutes 78 or more will be provided, depending on the intended use. As will be readily appreciated, to enhance the rotational resistance of fixture supports 40 and 70, fewer, longer (i.e., in the direction of outward extension and/or along the length of shaft 42) are preferable to a greater number of flutes 78 of shorter length and outward extension.

In the case where holes 22 of FIGS. 2-3 and holes 62 of box 50 of FIG. 4 are formed in plastic material, such as fiberglass reinforced plastic (FRP), fluting 48 typically engages such plastic material even better than when holes 22 and 62 are formed in a metal portion of the respective junction boxes.

FIG. 6 illustrates a junction box 90 according to yet a still preferred embodiment of the invention.

Junction box 90 includes features as in the above-described boxes, with the additional features such as an extension 92 in which an opening 94 which is open to the outside of the box is defined. Opening 94 is useful for allowing a potential customer to see a portion of fixture support 40 extending down through an upper portion of a hole 98, so as to gain a better appreciation of the features of junction box 90.

Hole 98 for receiving fixture fastener 40 will be configured for closely engaging preferably at least fluting 48 of fastener 40. It is contemplated that hole 98 will snugly engage fixture support 40 along as much as the entire length of shaft 42. Fluting 48 engages upper portion 96 of hole 98, in the manner described above.

Turning to FIG. 7, a still preferred embodiment of a junction box 100 according to the invention is shown.

Box 100 includes a recess or opening 102 having a seat 104 disposed therein. Recess or opening 102 is provided in side wall 18 or an extension 106 provided on side wall 18.

A hole 108 is sized and configured for receiving fixture fastener 70, as described above. For example, fluting 48 engages an upper portion of hole 108 in the region of seat 104, as will be readily appreciated.

Preferably, recess 102 is sized and configured for receiving square head 76 of fixture support 70 with little or no free space between the outer perimeter of head 76 and the three (3) upwardly extending squared off walls of recess 102.

Needless to say, the tighter the fit between the three (3) upstanding walls of recess 102 and the three (3) sides of 4-sided square head 76 which do not face outwardly of recess 102, when installed, the greater the resistance to rotation of fixture support 70 about its longitudinal axis. Such resistance to rotation assists fluting 48 in resisting rotational movement, which rotational movement might lead to the loosening of the connection between fixture fastener 70 and the remainder of box 100 and, less desirably, loosening of the connection between the fastener, such as fan fastener 49 of FIG. 2, for the installed electrical fixture (e.g., ceiling fan, chandelier, light).

FIG. 8 illustrates a junction box 110 according to a yet still further preferred embodiment of the invention.

Box 110 includes an optional extension 112 strengthening the region around side wall 118 and in which a hole 114 is defined.

Hole 114 includes an upper portion 116 and a lower portion 118, which lower portion 118 begins at a seat 120 for receiving a head 124 of a fixture support 126.

Fixture support 126 includes, preferably, internal threads 128 which mate with the threads of a fixture fastener 130.

Fixture support 126 may have fluting 58 for engaging with the material of the walls defining lower portion 118 of hole 114, as described above.

FIG. 9 illustrates another preferred embodiment of a junction box 140 according to the invention having a hole 144 defined therein.

Box 140 is similar to box 110 of FIG. 8; however, a hole 144 defined therein preferably has an upper portion 146 configured to mate with square head 148 of a fixture support 150.

Turning to FIGS. 10-11, yet another preferred embodiment of a junction box 160 according to the invention is shown.

Box 160 includes a hole 164 having an upper portion 166 and a lower portion 168.

A fixture support fastener 169 extends through upper portion 166 of hole 164 and engages with internal threads 172 of a fixture support 170. Depending on the intended use, internal threads 172 may be selected so as to mate with the external threads of both fixture support 169 and those of fixture fastener 130.

FIG. 11 is a cross-sectional view of junction box 110 of FIG. 10, after both fixture support fasteners 169 and fixture supports 170 have been installed in upper portion 166 and lower portion 168 of hole 164, respectively.

FIG. 12 shows another preferred embodiment of a junction box 190 according to the invention.

Junction box 190 includes an adhesive 192, such as a piece of double-sided tape 194 on top wall 14 thereof. Double-sided tape 194 may be provided with a protective strip or layer 198 on the outer face thereof, i.e., on the face of double-sided tape 194 that has not been adhered to junction box 190. Conventional double-sided tape 194 may be used.

Alternative means for adhering junction box 190 to a surface may be used, such as spray-on adhesive, a piece of putty and other adhering means. Such adhesive may be as described in my earlier U.S. patent application Ser. Nos. 08/490,757, filed Jun. 15, 1995, and 08/371,695, filed Jan. 12, 1995, each of which is incorporated herein by reference, and such adhesive may be utilized in conjunction with or instead of the double-sided tape 194.

One of the many advantages of junction box 190 is that the user may remove protective layer 198, and then adhere double-sided tape 194 to the surface to which junction box 190 is to be attached. Double-sided tape 194 is selected and sized so that sufficient holding power for temporarily adhering junction box 190 to the surface is achieved, while the user has both hands free for permanently attaching junction box 190 in the desired location by nailing nails (or shooting screws) through one or more holes 36.

Preferably, the adhesive is sufficiently strong to adhere box 190 to a downwardly facing horizontal surface located above the user's head.

The thickness of double-sided tape 194 is coordinated with the thickness (i.e., height) of the head of bolt 169, as required, so that each performs its intended function, when junction box 190 is provided with screw 169 of FIGS. 10-11.

In a like manner, the height of the external portion of other supplemental supports will be coordinated with the thickness of adhesive material or double-sided tape 194. For example, when screw 169 is used with junction box 190, the thickness of double-sided tape 194 typically will be selected to be at least as high, and preferably in most cases, higher than such height.

Alternatively, when attaching box 190 to a stud having a width less than the distance between left and right screws 169, double-sided tape 194 need not extend away from top wall 14 a distance greater than the height of the heads of screws 169. That is because the stud would fit in between the offset left and right heads thereof.

FIGS. 13 and 14 illustrate another preferred embodiment of junction box 200 according to the invention.

Junction box 200 includes a recessed portion 202 having a lower face 206 and a side face 207. Recessed portion 202 is preferably configured for receiving a mating metal plate or metallic element 208. Preferably, metal plate 208 is made of a material which can conduct electricity, and, hence, function as a part of the ground for the junction box, as will be described immediately herebelow.

Box 200 achieves the long-felt need for a plastic junction box which has its own ground. Such grounding is provided by a ground screw 210 securing the third or ground wire of standard alternating current (AC) wiring which has a positive wire, a negative wire, and a third, smaller and generally unsheathed grounding wire. Such grounding wire G is secured to metal plate or grounding plate 208 by screwing a ground screw 210 into a threaded hole 212 defined therein.

Metal plate 208 may be secured to in recess 202 by the use of a through hole or opening 216. Fixture fastener 70, as described in various embodiments above, extends through hole 216 and is secured in extension 220 owing to fluting 48 engaging one or both of plate 208 and hole 250, for example. Thus, the problem of easily lost prior art metal add-ons or clips on prior art boxes has been solved.

In this embodiment, a further recessed portion or "window" 232 is provided so that the user can see installed fixture support 70, in a manner similar to that described above regarding FIG. 7. A seat 104 of FIG. 7 is optional in window 232.

When box 200 is assembled, ready for use, a fixture, such as a ceiling fan can be secured by use of a ceiling fan fastener, along the lines described above. Needless to say, ceiling fan fastener is typically made of metal, and engages metal portions of the ceiling fan housing.

Hence, when the ceiling fan has been installed, and the wiring is completed, a ground will have been established through the ceiling fan housing, then through fastener 244, then through fixture support 70, through grounding plate 208, and through the grounding wire secured to grounding plate 208 by grounding screw 210. Thus, applicant has realized his goal of providing a plastic junction box having its own grounding.

Fixture support 70 extends through hole 216, through window 232, and into a hole 250. Fluting 48 has a length selected so as to engage at least the interior faces of opening 232, if not hole 216, shown as being slightly oversized to allow free passage of fluting 48 therethrough. It is contemplated that hole 216 be sized so as to engage metal plate 208; i.e., the inner walls of 216.

In addition to the benefits of functioning as a grounding element, grounding plate 208 further increases the carrying strength of junction box 200 owing to the forces transmitted through head 76 of fixture support 70.

It is contemplated that hole 240, sized to receive conventional light fixture fasteners 248, shown with the conventional rounded heads thereon, be provided with internal, plastic threads, as desired. By the use of internal plastic threads, self-tapping screws need not be used as light fixture fasteners 248.

Another important result of the embodiment of FIG. 13, as well as each of the embodiments of FIGS. 13-18, is the realization of the use of a larger proportion of less costly and more environmentally-friendly plastic material, with a reduced proportion of metal elements, so as to save on production and energy cost, and reduce the shipping weight which further reduces energy cost and, ultimately, the cost to producers and consumers.

FIG. 15 illustrates another preferred embodiment of the invention, similar to the embodiment of FIGS. 13-14, with the provision of a fastener 40 of the type described above having a round head 46. Junction box 260 may include the optional adhesive 192, such as the illustrated double-sided tape. Light fixture fasteners 248 have been omitted for clarity.

FIG. 16 illustrates a junction box 270 according to another preferred embodiment of the invention.

Box 270 may include a fixture support of the type described above regarding FIG. 10, for example, having fixture support fastener 169 extending through hole 164 and engaging internal threads of fixture support 170. Fixture support 170 has internal threads mating with fixture fastener 130, as described above.

FIG. 16A illustrates an optional grounding plate 278 for use with box 270 of FIG. 16. Metal plate or grounding plate 278 includes a threaded hole 282 for receiving a grounding screw, as described above, as well as a through hole 284 through which fixture support fastener 169 extends when grounding plate 278 is used. Hole 284 need not be threaded.

It is likewise contemplated that an additional hole be provided in a region 274 of extension 276 of FIG. 16, so that a second type of fixture fastener may be used on the same junction box, such as in the embodiment of FIGS. 13-15, for example.

FIG. 17 illustrates another preferred embodiment of a junction box 290 according to the invention. Junction box 290 is similar to the embodiment of FIG. 13; however, there is no window 232. Adhesive 192, such a double-sided tape, is shown in the exploded view to emphasize that adhesive 192 is optional. Protective layer 198 has been partially peeled away from double-sided tape 194, as such would be done immediately prior to adhering assembled junction box 290 to a surface, such as the side of a wall stud, or to the lower face of a ceiling joist.

FIG. 18 shows a junction box 300 which has round headed studs 40, and has no window 232 in its extension 294, unlike the similar junction box of the embodiment of FIG. 15.

As to the fixture supports, such as the illustrated supports 40, 70, and 90, and so forth it is likewise contemplated that such supplemental supports will have other cylindrical shapes, hexagonal-shapes, square shapes, and shapes which are tapered at an upper portion thereof. In addition, frustrums of pyramids and the other shapes are contemplated with truncation taken at angles other than the illustrated angles and removed portions, and other than the illustrated substantially right angle between the top face of respective supplemental supports of upper wall 14 of the various preferred embodiments of the junction box according to the invention. The length of the fixture supports will be varied depending on the intended use and depth (height) of the box, as required.

It is contemplated that fixture supports 40, for example, be provided in opposed pairs, as shown, for attaching a first type of fixture, such as a ceiling fan; and, on that same box, a second pair of opposed fixture supports 40 have the same or different threads from the first pair will be provided. That second pair of fixture supports 40 may be provided adjacent to or spaced from the first pair. For example, it is contemplated that a spaced apart pair of fixture supports be located adjacent the box side wall and each fixture support being between the first pair of spaced apart fixture supports. In other words, FIG. 2 shows two (2) supports 40 which may be considered to be located at the free ends of a negative ("-") sign. Two (2) additional fixture supports 40 may be added, whereby four (4) are present, one (1) of which is located at each of the four (4) free ends of a plus ("+") sign. The second pair would typically have a different thread size at the lower ends thereof, as compared with the first pair, so that one pair supports light fixtures, and the other pair supports ceiling fans, for example.

In addition to the screws used in the embodiments described above, it is expected that bolts or locking coupling nuts will be used to attach supplemental supports to the junction box, as well as any other means of fastening supplemental supports to the junction box in a sufficiently secure manner so as to achieve the objects of the invention.

It will be appreciated that these are merely examples of solutions to the problems set forth in my accompanying drawings and description, and, taken in its entirety, it will be appreciated that all the above objects of the invention, as well as many others, have been fulfilled.

It will likewise be appreciated that all the components described in the foregoing can be made of a variety of materials, such as steel, zinc, nylon, and other plastics, as the producer and user demand. For example, the box and the fixture support may be both made of plastic or both made of metal, or the box may be made of metal and the fixture support made of plastic, for example.

While this invention has been described as having a preferred design, it is understood that it is capable of further modification, uses and/or adaptations following in general the principle of the invention and including such departures from the present disclosures as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features set forth, and fall within the scope of the invention or the limits of the appended claims.