Push-on Grounding Bushing with Helical Locking Tabs
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Solution Overview
Problem
Existing push-on type grounding bushings face challenges in securely bonding insulated electrical conductors and conduits to earth ground while allowing for easy installation and removal, and accommodating various conductor orientations.
Innovation Solution
A push-type grounding bushing with a conductive body featuring a locking device with helical gripping tabs, a throat insulator, and an electrically conducting lug, which includes a lay-in recess for securing electrical conductors, allowing for mechanical and electrical grounding and accommodating different conductor orientations through a threaded bore and fastener system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a push-on type grounding bushing is used for easy installation, then installation speed and ease of operation are improved, but secure bonding of insulated electrical conductors to earth ground becomes problematic
Solution Approach 1:
The grounding bushing is segmented into distinct functional components: a push-on body for easy conduit installation, a separate locking mechanism with gripping tabs for securing the conduit, and a grounding system with lugs and fasteners for electrical bonding. This segmentation allows each component to optimize its specific function while working together as a complete grounding solution.
Solution Approach 2:
The grounding bushing incorporates pre-configured grounding lugs and fastener systems that are prepared in advance during manufacturing. The conduit locking mechanism with gripping tabs is pre-formed to engage with the conduit before the actual installation takes place, ensuring that when the installer pushes the conduit in, the grounding path is already prepared and will engage automatically.
2Strength
If a locking device with helical gripping tabs is used to secure conduits, then conduit holding strength is improved, but device complexity increases
Solution Approach 1:
The locking device incorporates helical (spiral/curved) gripping tabs that wrap around the conduit in a corkscrew pattern. This curved geometry provides superior mechanical interlocking and holding strength compared to straight tabs, while the helical form factor allows the locking mechanism to be compact and integrate efficiently within the bushing body.
3Reliability
If a throat insulator is used to cover the second end, then electrical insulation is improved, but the bore size for conductor passage may be reduced
Solution Approach 1:
The throat insulator is strategically positioned only at the second end of the bushing where conductor passage occurs, providing localized electrical insulation exactly where needed. The insulator features a precisely sized bore that maintains adequate clearance for conductor passage while minimizing material usage and preserving as much opening area as possible for the grounding lugs and fasteners to function effectively.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides secure bonding to earth ground, easy conduit installation and removal, and flexibility in handling various electrical conductor orientations, enhancing the usability and reliability of grounding bushings in electrical systems.
Implementation Method 1
a locking device placed in the first end of the body having a plurality of gripping tabs forming a helix so that the conduit can be pushed into the locking device and held by the plurality of gripping tabs
Implementation Method 2
the locking device has a plurality of gripping tabs forming a helix so that the conduit can be pushed into the locking device and held by the plurality of gripping tabs and removed by rotating the conduit relative to the body
Implementation Method 3
an electrically conducting lug secured to the body, the lug having a recess or bore dimensioned for receipt of at least one electrical conductor for providing grounding of the bushing
Implementation Method 4
a threaded bore formed through the top and extending into the lay-in recess, the bore for receipt of a fastener configured to mechanically and electrically secure the at least one conductor to the lug
Data Source
AI summary
A push-type grounding bushing has an electrically conductive body having a first end, a second end, a bore formed therethrough, and an intermediate shoulder stop to contact an end of a conduit. The bushing has with a locking device gripping tabs forming a helix so that the conduit can be pushed and held in the locking device and removed by rotating the conduit relative to the body. A throat insulator is placed into the second end of the body and has a flange to cover the second end. An electrically conducting lug is secured to the body and has a recess or bore for receipt of at least one electrical conductor to ground the bushing while a fastener mechanically and electrically secures the conductor to the lug.