Electrical box assembly

This invention relates to electrical junction boxes and specifically to an assembly that enables an installer to secure an electrical box to a block wall at a desired offset from the wall.

Walls constructed of concrete blocks or bricks are frequently finished with materials such as stucco, paneling, siding, or similar materials. These finishing materials are installed to enhance the attractiveness of the wall.

To provide electrical services to the wall, electrical boxes are commonly secured to the wall prior to installing the finishing layer. Prior to installing the finishing layer, the installer typically breaks a hole in a block at the desired location for an electrical box. The hole, typically made with a hammer and chisel, is usually somewhat larger than the box. Furring strips are then typically secured to the surface of the block wall to provide a brace for accepting the fasteners of a standard electrical box. The electrical box is then placed within the furring strips and secured at the desired depth within the wall to accommodate the finishing layer that will later be installed thereon. The electrical box is therefore mounted in a position where its front edge will be even with the surface of the installed finishing layer. Since numerous finishing materials are available, and they are available in different thicknesses, it is a very cumbersome and difficult task to install the electrical box with a great degree of certainty that it will be approximately even with the eventual finished layer surface. Standard electrical boxes typically have nails or screws set an angle to the front edge of the box and they typically tend to shift the box as the fasteners are hammered or screwed into the furring strips. To seal against drafts, the oversize hole is typically filled in by blowing pressurized foam, such as polyurethane foam, into the space between the box and surrounding block surface to seal the space between the box and the block. After the foam has cured, portions of it typically extend outwards of the block wall and from the base of the electrical box.

This prior art method of installing an electrical device is illustrated in FIGS. 12 and 13 . FIG. 12 depicts in exploded relationship an oversize hole 200 broken in the block wall 202 , two furring strips 204 secured to the wall by fasteners 206 , a prior art electrical box 208 , a duplex receptacle 210 , and a faceplate 212 . The furring strips 204 are secured to the wall, the prior art electrical box 208 is secured to one of the furring strips 204 by a fastener 214 , and a duplex receptacle 210 and a faceplate 212 are in alignment with the prior art electrical box 208 . FIG. 13 depicts a completed installation of a prior art electrical box 208 to a block wall 202 including the furring strips 204 secured to the wall 202 , the electrical box 208 secured to one of the furring strips 204 , and cured polyurethane foam 216 that has been used to fill the hole. With reference to FIGS. 12 and 13 , it should be apparent that this prior art method of providing an electrical box 208 on a block wall 202 is a tedious, labor intensive, time-consuming task that does not always result in the front edge 218 (see FIG. 12 ) of the electrical box being level with the eventual finished wall surface. In this prior art method of installing an electrical box to a block wall, it is difficult to get the proper offset from the anticipated surface of the later installed finished layer, as the prior art box is mainly intended for installation on framed walls, and the fasteners that come with the box are not positioned and angled to create a desired offset. The installer must therefore estimate the desired position of the electrical box to make it even with the finished wall.

What is needed therefore is a device that reduces the time and effort involved in installing an electrical box in a concrete block wall, brick wall, or similar surface, and enables the installer to easily mount the box at the desired offset from the wall's outer surface.

The invention is an assembly for mounting an electrical box on a wall such that the front edge of the box is at the desired offset from the wall's eventual surface. The assembly includes an electrical box and a slide member. The slide member includes a flange having a rear surface, an opening therein, and arms surrounding the opening and extending rearwardly from the rear surface. The electrical box includes sidewalls having apertures therein, a front opening, a front edge, and a cavity for receiving an electrical device. A mounting arrangement is included on the flange for securing the slide member to the wall. A fastening and adjustment arrangement is included on the arms for securing the box to the slide member and for adjusting the distance the front edge of the box is offset from the surface. The slide member is slideable with respect to the electrical box. A desired offset from the wall surface can be achieved by sliding the box within the slide member until the desired offset is achieved and then aligning guiding apertures in the slide member with receiving apertures in the box member and affixing a fastener therein to secure the box with respect to the slide member.

The assembly of the present invention simplifies the process of mounting an electrical box in a concrete block wall. Much less time and effort are required to install the electrical box of the current invention than is required with conventional methods.

Another advantage provided by the assembly of the present invention is that it eliminates the need for furring strips to prepare a block wall for an electrical box. This greatly reduces the complexity of installing electrical boxes to a block wall.

The assembly of the present invention also enables an installer to easily and accurately achieve the desired offset from the wall's surface. This is of critical importance on those walls that will be covered with a finishing layer such as stucco.

These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings.

FIG. 1 is a front perspective view of a preferred embodiment of a slide member that forms a portion of the assembly of the present invention.

FIG. 2 is a front perspective view of a preferred embodiment of an electrical box that forms another portion of the assembly of the present invention.

FIG. 3 is a perspective view of a preferred embodiment of the assembly of the present invention.

FIG. 4 is a front view of the slide member of FIG. 1 .

FIG. 5 is a sectional view of the slide member taken along line 5 — 5 of FIG. 4 .

FIG. 6 is an end view of the slide member taken along line 6 — 6 of FIG. 4 .

FIG. 7 is a front view of the assembly of FIG. 3 .

FIG. 8 is a sectional view of the assembly taken along line 8 — 8 of FIG. 7 .

FIG. 9 is a perspective view of the electrical box assembly of the present invention installed on a block wall.

FIG. 10 is a sectional view of the assembly installed on a wall with a first offset from the wall.

FIG. 11 is a sectional view of the assembly installed on a wall with a second offset from the wall.

FIG. 12 is an exploded perspective view of a prior art electrical box secured to a furring strip and with electrical components in alignment therewith for installation on a block wall.

FIG. 13 is a perspective view of the prior art electrical box of FIG. 12 after being installed on a block wall.

FIG. 14 is a top view of the electrical box of FIG. 2 .

FIG. 15 is a section view of the electrical box taken along line 15 — 15 of FIG. 14 .

The following is a listing of part numbers used in the drawings along with a brief description:

The present invention comprises an electrical box assembly for providing electrical service on a surface. It is especially useful on walls constructed of concrete block, brick, or similar materials.

With reference to FIGS. 1–3 , the electrical box assembly 20 includes an electrical box 22 having sidewalls 24 , a front opening 26 , a front edge 28 , and a cavity 30 for receiving an electrical device (not shown) therein.

Referring to FIGS. 14 and 15 , the sidewalls 24 of the box 22 include an inner surface 32 and one or more bosses 34 integral with and extending from the inner surface 32 of the sidewalls 24 and having bores 36 therein. One or more removable wall portions 38 are provided in the sidewalls 24 of the electrical box 22 . With reference to the sectional view of FIG. 15 , a duplex outlet 35 is shown in alignment with the bores 36 in the electrical box 22 and a faceplate 37 in alignment with the duplex outlet 35 to be secured thereto with fasteners 39 .

With reference to FIG. 1 , the electrical box assembly 20 further includes a slide member 40 that includes a flange 42 and an opening 44 therein. As shown in FIGS. 4–6 , the flange 42 includes a rear surface 46 and arms 48 integral with the flange 42 and extending inwardly (see IN arrow on FIG. 5 ) from the rear surface 46 , with inwardly referring to the direction with respect to the wall (not shown) that the slide member 40 will be fitted into. The arms 48 preferably extend perpendicularly from the flange. A mounting arrangement 50 is included on the flange 42 for securing the slide member to a wall surface (not shown). Brace members 51 extend horizontally from each side of the opening 44 in the flange 42 and extend vertically between the arms 48 thereby stiffening and adding support to the arms 48 and bracing them in their parallel relationship to one another.

As shown in FIG. 9 , which depicts the electrical box assembly 20 secured to a block wall 52 , the mounting arrangement 50 includes mounting apertures 54 in the flange 42 and mounting fasteners 56 for securing through the mounting apertures 54 in the flange 42 and into the surface 58 of the wall 52 .

With reference to FIG. 8 , a fastening and adjustment arrangement 60 is included on the arms 48 and on the electrical box 22 for securing the box 22 to the slide member 40 and for adjusting the distance the front edge of the box is offset from the surface. The fastening and adjustment arrangement 60 includes a plurality of guiding apertures 62 in the arms 48 , a plurality of receiving apertures 64 in the sidewalls 24 of the electrical box 22 , and at least one fastener 66 associated with each of the arms 48 for securing through the guiding apertures 62 in the arms 48 into the receiving apertures 64 in the sidewalls 24 of the electrical box 22 . It is preferred that the arms have a thickness of at least 0.050 inch to be structurally sound enough to provide stiffness with respect to the slide member 40 and also so that the arms 48 can structurally hold a fastener and also be stiff enough to prevent movement of the box 22 once they are secured thereto, such as in FIG. 8 .

Referring to FIGS. 6 and 14 , the guiding apertures 62 on the arms 48 are arranged longitudinally along the arms 48 in a linear alignment ( FIG. 6 ) and the receiving apertures 64 on the electrical box 22 are arranged longitudinally along the sidewall 24 of the box 22 in a linear alignment ( FIG. 14 ). When the electrical box 22 is inserted into the opening 44 in the flange 42 , as shown in FIG. 8 , the linearly aligned guiding apertures 62 in the arms 48 will be axially aligned with the receiving apertures 64 in the box 22 . Only one fastener 66 is required per arm 48 to secure the electrical box 22 to the slide member 40 . As the box 22 is slid with respect to the slide member 40 , there will be numerous possible axial alignments between the guiding apertures 62 in the arms 48 and the receiving apertures 64 in the box 22 . Therefore, the electrical box assembly 20 enables the setting of numerous offsets OS ( FIG. 8 ) between the surface 58 of the unfinished wall 52 and the expected finished surface 68 . The finishing layer 70 which will be installed on the wall dictates the expected finished surface 68 . The finished layer can be various thicknesses of stucco, siding, paneling, or various other finishing materials. The electrical box assembly 20 of the present invention therefore provides an easy and rapid method of placing an electrical box at the exact desired offset from the unfinished wall.

After securing the slide member 40 to the electrical box 22 with the fastening and adjustment arrangement 60 as shown in FIG. 8 , the electrical box assembly 20 consists of the slide member 40 and the electrical box 22 secured together as an integral unit as shown in FIG. 7 .

With reference to FIG. 4 , the flange 42 includes outward extending ribs 72 and a web 74 extending between each of the ribs 72 . The webs 74 have a thickness TW and the ribs 72 have a thickness TR (see FIG. 5 ). The thickness of the ribs 72 , which require structural strength to accept a fastener and hold the assembly 20 to a wall, is greater than the thickness of the webs 74 . The webs 74 extend between the ribs 72 and provide a means of masking the irregular shaped hole that the assembly is typically fitted within. Preferably the web 74 extends outward at least 0.5 inch from the opening. As the webs 74 perform a masking function, they do not require the larger thickness of the ribs 72 . As the preferred embodiment of the box 22 and slide member 40 of the present invention are typically each molded in one piece from plastic, minimizing the thickness of the webs 74 lowers production cost of the slide member 40 . In the preferred embodiment, the thickness of the webs 74 is preferably between 0.020 and 0.070 inch and the thickness of the ribs is preferably between 0.075 and 0.120 inches.

Referring to FIGS. 4 and 5 , the opening 44 in the flange 42 , although it is not limited to a single shape, in the embodiment shown herein the opening 44 has a rectangular shape and two sets of opposing sides 76 . The arms 48 are two in number and are typically adjacent the opening 44 in the flange 42 . The arms 48 extend from each side of one of the sets of opposing sides 76 . The arms 48 therefore include a first arm 48 A and a second arm 48 B in parallel planes 78 and 80 on opposing sides 76 of the opening 44 in the flange 42 . Each guiding aperture 62 in the plurality of apertures in the first arm 48 A is in axial alignment with a matching guiding aperture 62 in the plurality of apertures in the second arm 48 B.

With reference to FIG. 8 , the electrical box 22 typically includes opposing sidewalls 24 A, 24 B that have an outer dimension OD as measured across the opposing sidewalls 24 A, 24 B. The opening 44 in the flange 42 of the slide member 40 includes opposing sides 45 A, 45 B having an inner dimension ID as measured across the opposing sides 45 A, 45 B of the opening 44 . The outer dimension OD across the opposing sidewalls 24 A, 24 B of the box is preferably between 0.001 and 0.030 inch larger than the inner dimension ID across the opposing sides 45 A, 45 B of the opening 44 in the flange 42 . This is a critical dimension as the electrical box 22 must be slideable with respect to the slide member 40 but have enough clearance that the slide member 40 does not bind the box 22 and prevent it from sliding within the opening. As the arms 48 are parallel to one another, clearance between each arm 48 and the adjacent slide member 40 is also preferably between 0.001 and 0.030 inch.

With reference to FIG. 6 , the guiding apertures 62 in the arms 48 each include a center 82 . It is critical that the apertures 62 have a close enough spacing to enable a plurality of offsets with respect to the unfinished wall surface (not shown). It is preferred that the guiding apertures 62 in the arms 48 are spaced apart a distance of between 0.170 and 0.500 inch center to center.

With reference to FIG. 4 , the web portions 74 of the slide member 40 preferably include a plurality of apertures 84 therein. The apertures 84 are provided in the web 74 enhance the adherence of stucco (not shown) when the stucco is applied thereto to finish the wall surface. The apertures in the web 74 preferably include a diameter of at least 0.125 inch and no greater than 0.500 inch.

The electrical box and the slide member are each molded in one piece from plastic. Suitable plastic materials for the box and slide member include polycarbonate, polyvinylchloride, polyethylene, polypropylene, or acrylonitrile butadiene styrene.

The offset of the front edge of the box from the unfinished surface is determined by the fastening and adjustment arrangement, which includes selection and alignment of one of the guiding apertures in the arms with one of the receiving apertures in the sidewalls of the electrical box.

The reader is referred to FIGS. 10 and 11 for an understanding of the operation of the electrical box assembly 20 of the present invention. The electrical box 22 and slide member 40 could be provided as separate pieces but more typically would be provided as an assembly 20 (see FIG. 3 ) with the box 22 and slide member 40 secured together by the fastening and adjustment arrangement 60 . When provided as an assembly 20 , the box 22 would be secured to the slide member 40 and would include an offset, such as the offset O 1 shown in FIG. 10 . However, wall finishing materials have various thicknesses, such as ½-inch, 1-inch, 2-inches, and numerous others. Therefore, at the job site, if the job required an offset different than the preset offset, an installer would loosen the fastening and adjustment arrangement 60 and slide the electrical box 22 with respect to the slide member 40 until the desired offset was set. The offset O 1 is measured as shown in FIG. 10 , from the surface 58 of the unfinished wall 52 to the expected surface 68 of the finishing layer 70 . The installer would first make a hole 86 in the wall 52 with the hole 86 preferably larger than the sidewalls 24 of the electrical box 22 . With the electrical box 22 secured to the slide member 40 at the desired offset, the electrical box assembly 20 is then inserted into the hole 86 until the rear surface 46 of the flange 42 is flush against the unfinished surface 58 . The installation of the electrical box assembly 20 is completed by securing the assembly 20 to the unfinished surface 58 with the mounting arrangement 50 , including the mounting fasteners 56 driven through the mounting apertures 54 in the flange 42 and into the wall 52 .

As shown in FIG. 11 , a larger offset O 2 can be set by simply removing the fastener 66 of the fastening and adjustment arrangement 60 , sliding the box 22 with respect to the slide member 40 until an appropriate guiding aperture 62 is in axial alignment with an appropriate receiving aperture 64 , and securing the fastener 66 into the aligned apertures.

Having thus described the invention with reference to a preferred embodiment, it is to be understood that the invention is not so limited by the description herein but is defined as follows by the appended claims.