Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Reexamination Certificate
1999-06-28
2001-02-27
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
C174S135000, C174S064000, C248S056000, C016S002100, C016S002200, C029S735000, C029S868000
Reexamination Certificate
active
06194660
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to cable clamps for use with electrical distribution panels, outlet boxes, load centers, or the like, which are commonly used in campers, mobile homes, or other recreational vehicles to branch a main electrical current to various auxiliary devices.
2. Background Art
A variety of devices are used to secure electrical cables in the branch circuit apertures of electrical distribution panels. These cables are typically of rounded rectangular shape with nonmetallic insulation sheathing surrounding a pair of metallic wires. The distribution panel housings are typically made of non-conductive polymer material. Typically, the apertures in electrical distribution panels through which the cables are inserted are formed with removable plastic windows, or “knock-outs”, which temporarily cover the apertures until they are removed to allow insertion of electrical cables.
Clamping electrical cables in the apertures or knock-outs of electrical distribution panels in a manner that they cannot be easily pulled out or dropped into the outlet box is highly desirable for practical purposes, and is required by various industry codes. Conventionally, in the housing of an electrical distribution panel, electrical cables are secured by a variety of clamp-type or other devices. Some examples include molding cable clamps integrally with the electrical distribution panel housing; internal clamps comprising a single piece of material, such as an internal wedge member, for grasping the cable and which is incapable of moving through the knock-out opening; or forming the knock-outs with closure panels which remain connected to the interior walls of the knock-out opening and bear against the cable after insertion to hold the cable within the knock-out opening.
Some disadvantages encountered with conventional devices for securing the cables within the knock-outs of electrical distribution panels include the necessity of molding such devices within or contemporaneously with the panels, increasing the expense and complication of tooling and manufacture. In addition, many conventional devices frequently require additional tools or screwing steps for insertion of the cables. The integral serrations or “teeth” of conventional devices which secure the cable can cut into the insulation around the cable wire, which can compromise the conductivity of the cable by partially striping the cable insulation from the metallic wire when pulling strain is applied to the cable. Finally, many conventional cable clamps are specifically configured for securing cables of a single diameter size or gauge within the knock-out opening.
SUMMARY OF THE INVENTION
The present invention provides a cable clamp for securing a cable within a knock-out opening of an electrical distribution panel. The cable clamp consists of a wedge shaped head portion and a tail portion. The wedge shaped head portion is generally in the shape of a triangle, with hypotenuse, base, and tail sides. The hypotenuse side contains at least one relatively flat step parallel to the base side. The base side merges with the hypotenuse side at an acute angle to form a tip end, and has at lease one right angled step depending inward whereby each right angled step is positioned complimentary to the flat steps on the hypotenuse side. The tail side is transverse to the base side, and contains a tail portion which extends beyond the base side away from the hypotenuse side.
After the cable is initially inserted through the knock-out opening of an electrical outlet box, the tip end of the head portion of the clamp is inserted into the knock-out opening, squeezing the cable between the head portion of the camp and the interior wall of the knock-out opening. The tail portion facilitates hand gripping and provides a surface for hand pressing the clamp into position. For a relatively thicker diameter size cable, the clamp is pressed through the opening until the first step on the base side of the wedge shaped head portion passes through the opening, thereby locking the clamp into position with the cable securely pressed between the first obtusely angled step on the hypotenuse side and the interior wall of the knock-out opening. For a relatively thinner diameter size cable, the clamp is pressed through the opening until the second step on the base side of the wedge shaped head portion passes though the opening, thereby locking the clamp into position with the cable securely pressed between the second obtusely angled step on the hypotenuse side and the interior wall of the knock-out opening.
The clamp may be inserted from either the inside or outside of the housing of the electrical distribution panel, and no screwing steps, additional tools or other installation devices are required for installation. The rectangular knock-out opening of the housing cooperates with the shape and size of the clamp to provide these features. The clamp may be formed of a single piece of molded plastic material, which may be easily manufactured. In addition, the clamp lacks the integral serrations or “teeth” of previous designs, and therefore provides strain relief by merely indenting the insulation sheathing without either cutting through the insulation sheathing of the cables or partially stripping the insulation sheathing from the metallic wire when pulling strain is applied to the cable.
REFERENCES:
patent: 1827249 (1931-10-01), McCoy
patent: 4209661 (1980-06-01), Pate et al.
patent: 4414427 (1983-11-01), Slater et al.
patent: 4591658 (1986-05-01), Bauer et al.
patent: 4605816 (1986-08-01), Jorgenson et al.
patent: 4724282 (1988-02-01), Troder
patent: 5403976 (1995-04-01), Maurice
patent: 5932844 (1999-08-01), MacAller et al.
patent: 5984703 (1999-11-01), Weingartner
Baker & Daniels
Patel Dhiru R
Reichard Dean A.
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