Electricity: conductors and insulators – Boxes and housings
Reexamination Certificate
2001-05-22
2002-09-17
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Boxes and housings
C174S135000, C174S0450TD, C174S053000, C220S003200
Reexamination Certificate
active
06452096
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of commercial and residential electrical wiring installation and, more specifically, to the protection of electrical wires when they are pulled into and out of electrical junction or other electrical wiring boxes.
BACKGROUND OF THE INVENTION
As part of the process of installing or removing electrical wiring and/or fiber optics in commercial and residential buildings, it is common practice to run wire through tubular metal pipes or conduits which might be located in the walls, ceiling, floors, etc. The conduit runs terminate in open faced metallic junction boxes which provide access to the wiring which is otherwise encased within conduit. It is customary to securely mount these boxes within a wall, the ceiling , or the floor. During installation, wiring is pulled through a box and into the conduit until such time as the necessary length of wire within (and outside of) the conduit is obtained. In a related operation, it may be necessary to remove existing wiring from a single conduit or a an entire building, in which case the wiring is pulled out of the conduit. However, since these two operations implicate similar concerns, they will not be discussed separately hereinafter. Additionally, note that the term “wires” and “wiring” as they are used hereinafter will be used in the broadest possible sense to refer to conventional electrical power lines, as well as to computer network cables (including thick and thin Ethernet, twisted pair, etc.), fiber optic lines, etc.
Pulling wires into junction boxes and through the conduit fixtures can be a very difficult process because of friction between the wiring and the conduit. As a consequence, it may require a great deal of force to move the wire through the junction box and into the conduit. However, it is well known to those skilled in the art that the process of pulling wire into or out of a junction box risks damage to the wire from the sharp edges of that box. Pulling the wire across the edges of the junction box—and especially where that is done with great force—can potentially abrade the insulation covering of the wires, which can in some cases completely expose the interior of the wire. Obviously, wiring that has been damaged in this way poses a long-term threat to the integrity of the building wiring system.
In an ideal scenario, the conscientious electrician will strive to orient the wire so that it exits the box as nearly as possible at a 180 degree angle with respect to the conduit, so that when it is pulled the amount of friction generated thereby is reduced. This orientation also tends to minimize the risk of physical damage from the sharp edges of the junction box as the wire is moved past. Further, and in a perfect world, there will be another person on the other end of the wire to guide it into the box, thereby minimizing the same risks on the opposite end.
However, it is not always possible to pull the wire at the optimum angle because, for example, the box may be mounted near the floor or high above the electrician's head on the ceiling. (When working on a ladder it is much safer to pull “down” than “laterally”.) Further, the increased cost and inconvenience occasioned by the involvement of another person at the other end of the wire to guide it into the box may result in the electrician just performing the task by him or herself, at a risk of skinning the installed wire. As a consequence, it is not unusual to see an electrician pulling wire through the wall unassisted. Finally, even when it might be possible to do otherwise, some employees might choose not to pull at the “optimum” angle because they believe there is no real risk of damage to the wire or perhaps because it is just easier to do this operation incorrectly.
Others have considered this problem but the solutions suggested heretofore have not been entirely satisfactory. Wire guides in the shape of curved horns have been suggested for attachment to one end of a conduit where it is mounted to ajunction box so that the wires may be fed into the conduit at a proper angle. One example of such a device is described in U.S. Pat. No. 2,515,724. In U.S. Pat. No. 4,132,665, a rigid funnel for use in feeding wires through ajunction box and associated conduit is disclosed. These prior art devices have not found broad acceptance in the related trades because they tend to be relatively large and bulky and not very easy to use.
Other approaches use various combinations of rollers and pulleys. However, these approaches suffer from the disadvantage that they must be securely attached to the box, usually with thumb screws or the like (which results in additional time being spent to install and remove the device). Additionally, roller-based solutions are subject to their own friction/crimping problems. For example, if the wire is pulled at an angle that causes it to rub against a roller guide or roller support, binding of the wire and scraping of the insulation may result. Thus, these sorts of solutions can only accommodate wires that enter the device within a fairly narrow range of angles. Finally, solutions involving rollers or pulleys also tend to be relatively bulky and expensive to build. Since these sorts of devices are installed remotely from where the user is actually working, it is inevitable that the device will at least occasionally be forgotten and left at the job site where it could be lost or stolen. Obviously, the more expensive the device the less likely that an electrician would be willing to replace it and the electrician might choose instead to risk the possibility that hidden damage might be introduced into wires, which damage might not be discovered until months or years later. Examples of such prior art devices are disclosed in U.S. Letters Pat. Nos. 4,358,089; 4,033,551; 3,944,184; 3,113,759; 2,746,715; and 2,727,721. These references teach rigidly mounted, or rigidly held guides or pulleys which they can be used either for pulling wires into, or out of, electrical conduit.
Heretofore, as is well known in the electrical arts, there has been a need for an invention to address and solve the above-described problems. Accordingly, it should now be recognized, as was recognized by the present inventor, that there exists, and has existed for some time, a very real need for a device that would address and solve the above-described problems.
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or preferred embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.
SUMMARY OF THE INVENTION
In accordance with a preferred aspect of the instant invention, there is provided an electrical wire guide which serves to protect one or more insulated electrical wires as they are drawn into or pulled out of an electrical wiring junction box or similar rigidly mounted device.
Broadly speaking, the instant device is an edge protector which fits snugly over all four edges of a conventional junction box. The preferred embodiment takes the form of a rectangular frame which snaps onto and covers the sharp upper/outer edges of a box through which wire is to be pulled. It is preferable that the upper surface of the instant invention, i.e., the portion of the instant device that contacts the wire, be manufactured so as to be smooth and rounded so that wire may pass over it with out risk of damage. The rounded portion of the device is stationary, i.e, non-rotating, so that it is critical that at least this portion present a smooth contact surface to the wire. Additionally, the preferred method of attaching the instant device to the junction box is by way of a slot or groove which has been cut so as to match the box dimensions as nearly as is possible. Thus, the
Estrada Angel R.
Fellers Snider Blankenship Bailey & Tippens, P.C.
Reichard Dean A.
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