Electrical Utility Underground Calbe Insulator/Mount

W.S. Hampshire, Inc. partnered with Reliability and Design Engineers of a large Midwestern Investor Owned Utility to redesign a problematic pipe insulator used for underground transmission power lines. The material was changed from a molded thermoplastic to Ryertex Grade C, machined from tubing.

Thermoplastic parts were failing/breaking at about a 30% rate– so approximately 1 out of 3 inspected annually were breaking, creating the need for unplanned replacement. Initial projections for life of the thermoplastic parts were significantly longer that what was happening in actual installation.

In this case, the solution to the problem did not only center on the unit cost of the finished item, but a Total Cost of Ownership (TCO) savings resulted from eliminating steps such as field inspection/monitoring, labor costs of teardown plus new installation, and loss of time where those labor resources should have been deployed more efficiently.

The WS Hampshire part is designed for ease of installation plus longer lasting life. The customer’s desire was to install an insulator and “forget about it” rather than having to inspect constantly. A four (4) piece thermoplastic design with a total of 16 bolts & nuts was replaced by a two (2) piece, four (4) set screw configuration that also included a machined flat on the bottom piece as an installation guide.

Finally, since Ryertex Grade C can be easily machined with a standard grinding wheel, the insulator could be modified on site in case any accessibility or unforeseen installation issue would arise.

Sizes used range from 2″ – 8″ total diameter. WS Hampshire has the capability to machine Ryertex tubing upward of 30″ diameter if needed.

To learn more about this project or how our materials & fabrication solutions can benefit your requirements, contact us today.

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Capabilities Applied/Processes


CNC Machining

Equipment Used to Manufacture Part

Haas ST30SSY

Overall Part Dimensions

Pictured: 9.000″ ID x 10.500″ OD x 5.00″ W

Tightest Tolerances


Material Used

Ryertex Grade C

In process testing/Inspection performed

Dimensional Inspection: Visual Inspection

Industry for Use

Utility– Underground


Up to 300 pcs. Per size per order

Standards Met

Customer Specifications

Product Name

Underground Cable Insulator