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Barry Cordage Ltd

Developing the Best Dielectric Rope

Developing the Best Dielectric Rope

For the past 30 years, the Barry SR & ED team has undertaken immense efforts to not only develop a complete line of state-of-the-art dielectric rope systems, but continuously advance both the technical properties and knowledge of these products. This has positioned Barry as a world class leader in the science of dielectric ropes.

Significant Milestones
1998-2021: Dielectric Rope Assemblies

Barry provides to various public utilities and private contractors throughout North America, dielectric rope assemblies and specialized tools which offer unique dielectric and insulative properties.

1991-1993: Winch Lines for Remote Robotic Carriers

During this period, Hydro Quebec, the national Public Utility in the province of Quebec, was developing a remote robotic carrier to operate on live 735 kV AC transmission lines. Barry was mandated to assist in this endeavor to develop a winchline which could support the energized conductor(s) or to also be used to hoist tools or materials from the ground to the live conductors. This project led to several basic discoveries concerning the dielectric properties of various synthetic fibers, construction and coatings. The project resulted in the creation of a dielectric winchline which remained the only approved and certified product for use with the Hydro Quebec robotic carrier.

Photo: Hydro-Quebec

Photo: Hydro-Quebec

1996-1998: Live Line Stringing of OPGW

Barry was mandated by Hydro Quebec to develop dielectric pulling ropes in continuous 5 km segments and thousands of dielectric spacer ropes for the quadruple cradle-block method which would enable live line installation of OPGW (optical ground wire) under wet conditions over 735 kV AC transmission lines. The project was a huge success and the products developed by Barry are still present in the marketplace today.

Live Line Stringing of OPGW

Photo: Hydro-Quebec

2006: Dielectric Helicopter Longlines

Barry develops the first dielectric helicopter longlines using its knowledge acquired through its R&D commitment and through decades of expertise and participation in the dielectric rope field and helicopter external equipment industry. This is the first dielectric helicopter longline developed to assist electrical utility companies, helicopter operators and contractors perform HEC and NHEC work in energized fields. A huge advancement created is that these longlines can be periodically tested and easily maintained as fibreglass reinforced plastic (FRP) hotsticks and provide protection from phase to ground and phase to phase contact on either AC or DC transmission systems.

Dielectric Helicopter Longlines

2015: Dielectric Safety Nets

Barry was mandated by Manitoba Hydro to develop dielectric safety nets for various major transmission stringing projects throughout the province which were to be carried out under various harsh environmental conditions. The dielectric nets are strung across rider poles and act as guard structures which create a separation between the overhead conductors or guard wires and the ground or another energized line crossing below the nets. In the case of a dropped conductor, the nets will prevent outages and increase safety to workers.

These dielectric nets also increase safety during their removal and installation compared to conventional rope nets because of their excellent insulative properties. The dielectric nets can be periodically tested, maintained and field repaired as part of a servicing contract with Barry. They have proven to be exceptionally durable and reliable, even when left exposed to rain and snow in direct phase to phase contact for several weeks at a time.

Dielectric Safety Nets

(Photos: Manitoba Hydro)

2016: Rescue Systems & Hoist Systems

Barry develops the first dielectric rescue ropes for self-evacuation and rescue from energized environments.

The Barry rescue ropes were introduced to overcome the hazards associated with the use of kernmantle and double-braid polyester ropes in energized environments as such ropes could become very conductive from slight amounts of moisture or humidity and can give fatal shocks and melt, burn, flashover and fail mechanically.

The Barry D.E.W. Line® rescue ropes are the only true dielectric rescue ropes available on the market. They were developed to be Arc Flash (Category 4) resistant, dielectric when wet, rated for human loads and to work with approved NFPA or CSA rescue descenders and specialized pulley blocks. Barry designed various system configurations adapted for Distribution and Transmission bucket truck escape and for Transmission tower or conductor car victim rescue or self-evacuation. The unique Barry systems offer a tremendous advantage as they can enable the complete retrieval of anchor slings on the towers or conductors,  so that no slings or hardware is left aloft after the rescue descent to the ground is completed.

Barry also developed a one-of-a-kind Hoist System using the Barry D.E.W. Line® dielectric rescue rope which can assist in retrieval, raising or lowering  of injured workers who may have fallen and are suspended in their harness. The easy to operate and fail -proof system provides the required insulating protection  to the worker and rescue team and is an essential component to any rescue plan and method.

Rescue Systems & Hoist Systems

2017: Barry D.E.W. Line® Trademark & Dielectric Work Tools & In-House Electrical Testing Lab

The Barry D.E.W. Line® brand and trademark receives official registration.

D.E.W. stands for Dielectric Even Wet and is the mark of unequalled product quality. A variety of specialized dielectric rope tools are developed and fine-tuned for specialized work in the live line environments, for voltages up to 735 kV, whether wet or dry. Certain work rope models can be knotted due to special proprietary coating formulations which were developed by Barry. All these products can be periodically tested and easily maintained as FRP hotsticks and provide protection from phase to ground and phase to phase contact on AC or DC systems. A lightweight tag line was developed for fault initiation and offers insulative protection from high fault currents due to both dielectric and arc flash properties.

Barry established its in-house state-of-the-art electrical laboratory to support its R&D commitment, to elevate its quality control measures, improve efficiencies and offer quick delivery of product.

Barry D.E.W. Line® Trademark & Dielectric Work Tools & In-House Electrical Testing Lab

(Photo: Barry and Manitoba Hydro)

2018 : Barry Mono Zip Cart and saddle

The Barry team developed a lightweight conductor car (conductor trolley) which is a very useful equipment for maintenance of conductors, whether energized or not. It was designed to support a lineman and tools and ride on a single conductor to carry out inspections or to install spacers, spacer dampers, or other attachments, where required. An engineering analysis and report, FEA, and certification completed the design process for this innovation, which has its own User Manual covering safe use, limitations, maintenance and inspection criteria to support the end-user. The wheels enable use on conductors ranging from 10 mm to 60 mm in diameter. The wheels are available in non-conductive materials or in hard anodized aluminium if required to be conductive. The saddle has a fully adjustable and ergonomic design. It is padded and includes an insulated foot rest for comfort . Large pockets to transport tools and equipment is included. The lateral anchor points enable attaching the Barry D.E.W. Line® as a dielectric safety rope.

Barry Mono Zip Car and saddle

Technical Challenges Encountered Solutions Found:

Over the three decades of ongoing research into developing the Best Dielectric Rope, some technical challenges were encountered. During the initial stages of product development, fibers such as nylon, polyester, polypropylene, co-polymers, Kevlar, Spectra (HMWPE) and E-glass, and others, were conditioned and tested at various voltages at a high voltage laboratory, using saline mist vapors and full immersion in conductive water.

It soon became apparent that the uncoated fibrous ropes would absorb the moisture and would lead to flashover or give excessively high leakage current values. In cases of open weave fiber ropes, the temperature and leakage current increased quickly until the internal humidity was steamed off which dried the rope and decreased the leakage current values. In other cases, the temperature increased significantly and often led to flashovers which melted or carbonized the fibers, thereby destroying the rope s mechanical strength and integrity.

Various overlay finishes such as silicon water repellent coatings, carnauba and palm waxes, chlorinated hydrocarbons (perchloroethylene), PVC, TPR, etc, proved deficient in providing a reliable solution. It was concluded by the Barry team that the only solution was to extrude a thermoplastic jacket over the rope fibers. Such a jacket would seal and protect the inner fibers and would enable cleaning the exterior of the ropes to rid them of external contamination which was also noted as a problem during handling and use. The search for the perfect combination of materials which met the electrical and mechanical criteria began.

Clear vs Opaque exterior coatings.

On earlier generations ropes dating 1994-96, Barry made its extruded thermoplastic jacket for ropes using clear compounds with the idea that the internal fibers. However, this proved to be a mistake and the idea was abandoned as the clear coatings would either cause the internal fibers to breakdown more rapidly and be weakened when exposed to UV radiation, or would eventually become opaque, thereby defeating the purpose. In any case, it was determined that it is quasi-impossible to inspect reliably the core of a rope through the coating. Any (unlikely) internal issues within the core rope are not readily visible and would be best determined by visual inspections of the contrasting color exterior coatings on the Barry ropes and through more reliable mechanical and electrical testing.

 Clear vs Opaque exterior coatings.

(First generation clear jackets)

The current Barry D.E.W. Line® rope generation includes reliable wear/abrasion contrasting color indicators, which is not possible to do with the use of clear coatings. They are made using darker colorations with UV inhibitors and other additives which enhance the product resistance to UV, improve abrasion resistance and flexibility and provide optimized arc-flash and dielectric resistance and permittivity.

Modern generation opaque jackets

(Modern generation opaque jackets)

Internal Humidity Markers

Barry has tested various forms of internal adsorption materials and markers which would change color in case that humidity had penetrated underneath the extruded thermoplastic jacket and thereby possibly affect the product’s dielectric properties. Although the idea of having a simple and quick-fix indicator is appealing, such markers or indicators are either un-reliable and potentially seriously misleading. It was concluded that the only reliable method to detect moisture presence or contamination was through pre-use inspection and electrical testing.

Current Barry D.E.W. Line® Products offered:

Barry offers not just rope but rather rope tools which have a serial number delivered in high quality storage bags with a User Manual describing in detail the product’s limitations, methods for care and maintenance and on-going testing to ensure that the product is kept in optimum conditions to continue being the best dielectric rope available on the market and meet with success the end users' needs.

Current Barry D.E.W. Line® Products offered:

Warning: Not all dielectric ropes are created equal. There are synthetic fiber ropes with an overlay finish as well as poor imitations of extruded thermoplastic jacket ropes offered on the market by vendors making false claims and others who  have not properly tested their product to the applicable International Standards. Our advice is to stay clear of such deficient products and only source your dielectric rope products from a reliable provider who can offer a complete service, support, documentation and expertise acquired through their own work and research. Barry is such a provider.

Unique advances:

  • Unique and extremely low leakage current values wet or dry
  • Meets and exceeds all International Insulating rope standards
  • Unique compounds make it Arc Flash resistant to Category 4
  • Can be cleaned and maintained and tested as per FRP tool/ hot stick
  • Individually serialized rope tools which can be tracked and logged.
  • Lightweight and high strength
  • Complete User Manual

The Future:

The Barry team never rests on its past and present successes. It is always looking to the future. It listens to industry needs and seeks to create, enhance and optimize its products and services in order to augment worker safety and productivity.

Some projects in the works:

  • T-Bird aerial modular work access platforms for Class D helicopter work
  • Dielectric Insulator string hoist and transport harnesses
  • Dielectric Sheds for Boom Truck Masts
  • Rope Inspection and Testing Tools
  • Advancements in materials for optimum durability and flexibility
  • Periodic Testing Capabilities under AC and DC Conditions

Posted by Patrick Barry on

Note: Barry sells to companies, professionals, and government only.
Note: Minimum quantities may apply to some products, $150 minimum purchase, sales by phone, fax, website and email only.
Note: This information is for reference only and is subject to change without prior notice.
Note: Any Barry document received by email, downloaded or printed is uncontrolled.

Note: Barry sells to companies, professionals, and government only.
Note: Minimum quantities may apply to some products, $150 minimum purchase, sales by phone, fax, website and email only.
Note: This information is for reference only and is subject to change without prior notice.
Note: Any Barry document received by email, downloaded or printed is uncontrolled.

Barry Cordage Ltd.
6110 boul. des Grandes Prairies
Montreal (Quebec)
Canada, H1P 1A2

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Web site:
Toll-Free: +1-800-305-2673
Telephone: +1-514-328-3888

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