The present invention generally relates to hardware for an electrical fixture and more specifically, to a grounding conductor for a grounding wire.
According to 2008 National Electrical Code Article 690.43, solar photovoltaic module frames and supporting structures must be grounded when installed. There currently are a few different options available to help meet this requirement. The most common option is a “direct-bury” lay-in lug, which is either extruded or cast, commonly from tinned copper. Direct-bury lugs were designed for other purposes, such as bonding metallic conduits, which make them less than ideal for running grounding conductors underneath strings of photovoltaic modules.
The present invention provides a grounding lug having a conductive housing, a clamping pad and a lay-in feature. The lay-in feature allows an installer to loosely place a grounding wire in the grounding lug, whereby the wire can be positioned and adjusted before final installation without disengagement of the clamping pad or removing the wire from the grounding lug. The lay-in feature therefore allows the installer significant freedom of movement during installation. For example, when the grounding lug is inverted and installed on the underside of a solar photovoltaic (“PV”) module, the lay-in feature can support the grounding wire against gravity, thereby facilitating the installation of the wire by allowing the installer freedom to manipulate and place the wire without the wire falling out of the grounding lug.
Using the lay-in feature, an installer can freely place and arrange the grounding wire in a plurality of grounding lugs before final installation. Once a final arrangement of the grounding wire has been achieved, the installer can tighten the clamping pad of each of grounding lug to securely couple the grounding wire to the housing to ground each module.
The invention provides a grounding lug having a housing defining an opening for receiving a wire and a clamping pad movable relative to the housing. The clamping pad is movable between an unclamped position in which the clamping pad defines a wire-receiving pocket in combination with the opening defined by the housing, and a clamped position in which the clamping pad clamps the wire to the housing. The grounding lug also includes a moving mechanism coupled to the housing and the clamping pad for moving the clamping pad between the unclamped and clamped positions.
According to another aspect of the invention, a clamp or lug has an angled design to provide clearance for the use of power tools for mounting hardware installation and wire clamping operation.
According to one aspect of the present invention, an angled design of the grounding lug provides clearance for the use of tools for mounting the grounding lug onto a hardware installation (e.g., a PV module frame) and for moving the clamping pad to effect clamping of the wire between the clamping pad and the housing.
According to another aspect of the present invention, the clamping pad includes one or more tabs protruding from upper and/or lower portions of the clamping pad. The tabs can engage sidewalls of the housing as the clamping pad is moved between the unclamped and clamped positions to reduce or prevent side loads from acting on a base of the housing, which may cause sidewalls of the grounding lug to spread during ground wire installation and prevent adequate holding force between the clamping pad and the housing.
According to another aspect, a resilient member, such as a spring, can be used to facilitate the positioning of the clamping pad prior to installation. For example, the spring may resiliently bias the clamping pad to the unclamped position, but allow for movement of the clamping pad in the direction of the clamped position to facilitate installation of the grounding lug on the mounting frame.
According to another aspect, the housing and the clamping pad can have a stamped sheet metal design that allows the grounding lug to be manufactured by a relatively inexpensive stamping process from a broad variety of materials and alloys.
According to another aspect of the invention, a grounding lug or grounding clamp is made of stamped metal, such as stamped copper alloy or stainless steel.
According to a further aspect, all hardware of the lug and/or clamp is of the same drive style and size.
A major objective in the solar industry is to reduce the cost-per-watt for the manufacture and installation of PV modules. The grounding lug disclosed herein is relatively inexpensive to manufacture and can reduce installation times, leading to a reduced overall cost-per-watt when installed on solar PV modules and frames. In addition, the stamped lug can be supplied with the appropriate mounting hardware to help with proper installation and to help maintain grounding continuity for the life of the installation.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail one or more illustrative embodiments of the invention, such being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.
In the annexed drawings, which are not necessarily to scale:
Referring now to the drawings in detail and initially to
With additional reference to
The blank 22 has a base 24 having a through hole 26 stamped therein. The base 24 is generally planar and the through hole 26 is configured to capture mounting hardware, such as a fastener 28 or other fastening mechanism for mounting the base 24 to a piece of equipment, for example, as described below with respect to
The blank 22 also includes a pair of side panels 30, which may be substantially the same as one another. The side panels 30 are bent parallel to one another and generally perpendicular to the base 24 by folding the side panels 30 relative to the base 24 generally along lines A (
As shown in
As shown in
The side panels 30 are stamped with a generally V-shape cutout 44 (
As best shown in
The blank 22 also includes a rear panel 46, which is folded relative to the base 24 generally along line B to form a rear wall 48 of the housing 12. To facilitate the folding of the rear panel 46 relative to the base 24, the blank 22 includes a pair of notches 60 between the base 24 and the rear panel 46. The rear panel 46 also includes a rear through hole 62 that may be threaded for receiving the moving mechanism 18. Additionally or alternatively, the rear through hole 62 may be configured for receiving a rivet 64, with the rivet 64 configured for coupling to the moving mechanism 18 to the housing 12.
The rear panel 46 may be bent so as to form an angle a with the base 24. For example, as shown in
As shown in
Although illustrated as being constructed from a stamping process, the housing 12 can be formed from other manufacturing techniques, including, for example, die casting, molding, etc.
Referring now to
The clamping pad 16 has a width W1 that is slightly less than a width W2 (
As shown in
Although shown as having tabs protruding generally from the four corners of the clamping pad 16, other configurations are possible. For example, the clamping pad 16 may only include the upper mounting tabs 68 without the lower mounting tabs 72, or may include the lower mounting tabs 72 without the upper mounting tabs 68. Other variations are also possible, such as only having mounting tabs protruding from one side of the mounting pad, etc.
The upper tabs 68 and lower tabs 72 are separated from one another by a space 78. The space 78 can be configured and/or sized to receive the sidewalls 32 when the clamping pad 16 is assembled to the housing 12. The upper edge 34 and/or lower edge 36 of the sidewall 32 provide a track or guide along which the clamping pad 16 is slidable.
The clamping pad 16 includes a through hole 76 for receiving the moving mechanism 18. The through hole 76 may be tapped for engagement with the moving mechanism. The face 79 of the clamping pad 16 may have a textured surface or surface portion with any of a variety of surface texture elements to aid in gripping of a wire. For example, the face 79 may have a knurl pattern that may increase the friction used to hold the wire in place.
Rotation of the moving mechanism 18 causes longitudinal movement of the clamping pad 16 along the upper and lower edges 34, 36 of the housing 12. The tabs 68 and/or 72 inhibit and/or prevent rotation of the clamping pad 16 relative to the sidewalls 32 by engaging the upper 34 and/or lower 36 edges of the sidewalls 32 as the clamping pad 16 is driven by the moving mechanism 18 (
An alternative clamping pad 80 is shown in
Referring now to
In the exemplary embodiment of
The moving mechanism 18 has a fixed length that may be selected based upon the gauge of the wire to be received in the wire-receiving pocket 20. The length of the moving mechanism 18 may be long enough to allow a #14 through #6 AWG bare grounding wire (e.g., a solid or stranded wire) to slide into the wire-receiving pocket 20 while being short enough to allow an installation tool to install the mounting hardware without significant interference from the clamping pad 16 (
The elongate portion 86 of the moving mechanism 18 is coupled to the housing 12 via the rear through hole 62. For example, the rear through hole 62 may be threaded for engagement to the moving mechanism 18 or configured to hold the rivet 64, with the moving mechanism 18 coupled to the housing 12 via the rivet 64. In one embodiment, the rivet is a spin rivet. The rivet allows the housing to be stamped from a thinner material while retaining an allowable amount of threads for proper screw clamping force.
The head 87 can allow for the use of a socket, flathead screwdriver and/or Phillips screwdriver to tighten the screw, thereby moving the clamping pad 16 from the unclamped position to the clamped position. The head of the drive screw may match the fastener 28, which allows an installer to use a single installation tool. The moving mechanism 18 also can be reverse-drivable so as to allow the clamping pad 16 to be moved from the clamped position to the unclamped position by driving the moving mechanism 18 in the opposite direction.
The clamping pad 16 is biased to the unclamped position by the resilient member, which is shown as a compression spring 90 in
The spring 90 extends between the clamping pad 16 and the rear wall 48 of the housing 12. The spring 90 may press the clamping pad 16 against the flange 88 of the moving mechanism 18. For example, the spring 90 may be slightly compressed between the clamping pad 16 and the rear wall 48 or rivet 64 when the clamping pad 16 is in the unclamped position. As described below, the spring 90 can allow the clamping pad 16 to resiliently deflect towards the rear wall 48 of the housing 12 by the installer or installation tool during the mounting of the grounding lug onto the mount plate. Once installation is complete, the spring 90 causes the clamping pad 16 to deflect back to its original position. The spring 90 can therefore insure that a clearance gap remains for the grounding wire to slide between the clamping pad 16 and the housing 12.
During general use, the grounding lug 10 is inverted and installed on the bottom of an electrically conductive mounting surface of a piece of equipment or another component with hardware installed by a hand tool or a power tool. When installed, a grounding wire can be placed within the wire-receiving pocket 20 and held in location by resting on the clamping pad 16 and the housing 12 such that gravity does not cause the grounding wire to fall out of the wire-receiving pocket 20 when the grounding lug 10 is mounted underneath a mount plate.
An exemplary method for mounting the grounding lug 10 underneath a mount plate 92 (e.g., a PV module) is shown in
With specific reference to
Referring now to
The wire 96 is slid into the wire-receiving pocket 20 as shown in
As shown best in
Driving the moving mechanism 18 causes the clamping pad 16 to move the wire 96 along a length of the opening 14 until it is clamped against the housing 12 by the clamping member 16 as shown in
As will be appreciated, the grounding wire 96 can be released by driving the moving mechanism 18 in the opposite direction to move the clamping pad 16 to the unclamped position such that the clamping pad 16 and the housing 12 form the wire-receiving pocket 20 from which the wire can be removed, rearranged, replaced, etc.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.
This application claims the benefit of U.S. Provisional Application No. 61/225,316, filed Jul. 14, 2009, which is hereby incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
61225316 | Jul 2009 | US |