Midpoint Cable Ground Clamp for Armored Wire
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Solution Overview
Problem
Existing methods for connecting a ground wire within spiral metal sheathing to a ground point along a cable length are cumbersome and fail to securely grasp the metal sheathing ends, making it difficult to meet code requirements.
Innovation Solution
A ground fitting with a wire clamp and clamping plates that securely hold the ground wire laterally and the metal sheathing ends, using a ground screw and plate screws to ensure a robust connection, allowing for easy midpoint connection without threading through the sheathing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the spiral metal sheathing is cut and sheathing is removed to expose the ground wire for connection, then the ground wire can be accessed for electrical connection, but the complexity of the connection process increases and time is lost due to the need to remove and replace sheathing
Solution Approach 1:
The ground fitting is divided into distinct functional segments: a sheathing retention section with clamping plates that hold the metal sheathing, and a ground wire access section with a lateral opening that allows ground wire insertion without disturbing the sheathing. This segmentation enables simultaneous sheathing retention and ground wire access, eliminating the need to remove and replace sheathing sections.
Solution Approach 2:
The ground fitting acts as an intermediary device that interfaces between the metal sheathing and the ground wire. It provides a lateral opening that mediates access to the ground wire while the sheathing remains intact, thus simplifying the connection process without requiring sheathing removal and replacement.
2Reliability
If known fittings are used to ground armored ground wires, then electrical connection can be achieved, but the metal sheathing ends are not sufficiently grasped to meet code requirements
Solution Approach 1:
The clamping plates feature concave dished portions with interior ridges that conform to the curved spiral surface of the metal sheathing. This curved geometry provides superior engagement and grasping of the sheathing ends, ensuring reliable mechanical and electrical connection that meets code requirements.
Solution Approach 2:
The clamping plates are designed with ridges that replicate and engage the spiral pattern of the metal sheathing. This ridged structure copies the sheathing's external geometry, providing optimal contact and secure retention of the sheathing ends without requiring complex additional components.
3Ease of operation
If the ground wire is threaded through the sheathing from the end, then connection can be made, but the process becomes difficult especially when a long length of sheathing has been removed
Solution Approach 1:
Instead of threading the ground wire through the sheathing from the end in the conventional direction, the ground wire is inserted laterally through an opening in the ground fitting that is positioned perpendicular to the sheathing axis. This inverted insertion approach allows ground wire access without requiring the sheathing to be removed or threaded through, dramatically simplifying the installation process.
Data Source
AI summary
A ground fitting allows simplified electrical connection between a ground wire carried in a metal sheathing, and a ground point such as a water pipe or ground rod. The metal sheathing is cut and separated and a short length of ground wire is exposed. The ground wire is inserted laterally into a wire clamp portion of the ground fitting, and opposing ends of the metal sheathing carrying the ground wire are inserted longitudinally under clamping plates on opposite sides of the ground fitting. A ground screw is tightened against the ground wire to hold the ground wire in the ground fitting and plate screws securing the clamping plates are tightened to secure the sheathing between the clamping plates and clamp seats. Ridges may be provided on one or both of the clamping plates and the clamp seat to engage a spiral exterior surface of the metal sheathing.