Should localized mechanical damage puncture a cable’s outer jacket, this swelling tape substrate expands into a dense gel matrix upon fluid contact, preserving internal insulation integrity. While non-conductive variants suit low-voltage lines and fiber optics, high-field power environments demand this specialized semi-conductive performance to eliminate internal voltage differentials and prevent partial discharge.

Understanding the electrical and swelling mechanisms

When fresh or salt water touches superabsorbent polymer (SAP) fibers, a cross-linking reaction triggers swelling within seconds. In power cable construction, these SAP elements are combined with woven or non-woven polyester matrices to deliver specific mechanical and electrical properties.

+-------------------------------------------------------------------------+
|                  HIGH-VOLTAGE CABLE INTERIOR CROSS-SECTION               |
|                                                                         |
|   [ Conductor ] --> [ Semi-Conductor ] --> [ XLPE Insulation ]          |
|                                                                         |
|   --> [ Semi-Conductive Water Blocking Tape ] <--- (Gili Test Swell Zone)|
|                                                                         |
|   --> [ Metallic Shield / Screen ] --> [ Outer Polymeric Sheath ]        |
+-------------------------------------------------------------------------+

1. Non conductive water blocking tapes: Formulated from high-purity non-woven polyester fabrics, these tapes offer high swell capacity and dielectric isolation. They serve as mechanical separators and moisture barriers in low-voltage distribution, telecom, and control cables where field stress control is unnecessary.
2. Semi conductive water blocking tapes: Formulated with carbon black formulations, a semi conductive maintains a continuous conductive pathway across the core interface. By matching the electrical potential between the insulation shield and metallic screen, it eliminates localized partial discharges.

Technical comparison matrix

Designing cable cores according to US industry frameworks—such as guidelines published by the IEEE (Institute of Electrical and Electronics Engineers)—requires strict verification of surface resistance and swell height:

Selecting the right tape for cable architectures

When engineering multi-core or single-core power cables, choosing between conductive and non-conductive variants dictates long-term cable reliability:

• Medium-voltage (MV) distribution cables: Applying a semi conductive water blocking tape over the XLPE insulation screen ensures smooth equipotential contact with copper wire screens or corrugated aluminum sheaths.
• High-voltage (HV) subsea cables: Submarine power links utilize a reinforced semi conductive water blocking tape under lead or aluminum sheaths to absorb hydrostatic water surges while draining capacitive charging currents.
• Dry-core fiber optic cables: Non-conductive tapes replace traditional messy gels, providing clean, swellable protection in outdoor duct cables.

Utilizing a high-capacity semi conductive water blocking tape protects the cable assembly during temporary overload temperatures up to 230 °C without losing swell performance or conductivity.

FAQS

Engineered textile components—specifically flexible cotton filler cords—play a decisive role in resolving geometric imbalances in multi-conductor cable layups.

The geometric challenge in multi-conductor layups

During the planetary cabling or stranding process, bundling multiple insulated conductors inherently leaves empty gaps (interstices) between cores. Following criteria from the Insulated Cable Engineers Association (ICEA), advanced industrial cable design requires filling these voids to prevent three primary mechanical failures:

1. Jacket collapse during extrusion: High-pressure molten polymer forces the outer sheath into unfilled gaps, resulting in an irregular, non-concentric outer profile. This irregular wall thickness creates weak points prone to physical tearing.
2. Stress concentration points: Unanchored conductors shift during repeated bending, creating localized strain points that cause insulation abrasion and core displacement.
3. Internal friction and heat build-up: In continuous-flex applications (such as drag chains or robotics), unguided conductor movement increases internal friction and thermal wear, shortening operating life.

Technical advantages of natural fiber structural fillers

Integrating soft, high-tensile textile elements inside the cable assembly resolves these mechanical issues without compromising flexibility or adding unnecessary dead weight. In modern industrial cable design, flexible fiber fillers are precisely dimensioned to match the interstitial volume of multi-core assemblies. By conforming dynamically to tight bending radii, they distribute internal mechanical stresses evenly across the conductor bundle while delivering four critical structural advantages:

Furthermore, natural fiber materials offer excellent compatibility with surrounding extrusion compounds. Unlike rigid plastic fillers that can create sharp internal edges under severe bend radii, soft textile yarns compress uniformly, distributing mechanical stresses evenly across the conductor bundle.

Primary applications in high-flex cable manufacturing

Engineered textile filling yarns are specified across demanding cable families where dynamic endurance, mechanical durability, and sound industrial cable design are mandatory. In continuous-flex environments, these high-tenacity yarns stabilize internal core geometry under severe torsional forces, preventing core displacement and friction-induced thermal wear over millions of bending cycles:

• Automated motion & control cables: Used in cable tracks, robotic arms, and automated assembly equipment subjected to millions of bending cycles.
• Mining & heavy-duty trailing cables: Providing internal impact absorption against severe crushing loads and surface abrasion in harsh environments.
• Elevator & hoist cables: Ensuring geometric symmetry and preventing core slippage across long vertical suspensions.
• Marine & offshore cables: Supporting internal compactness and structural integrity under high mechanical tension.

FAQS

At Juan Gili S.L., we develop and supply technical textile substrates and components engineered to optimize the application of these mineral tapes in high-speed taping and lapping lines for cable manufacturers.

Physicochemical properties of mineral insulation

Mica is an aluminosilicate mineral with a sheet-like (laminar) structure that delivers a unique combination of thermal and electrical properties essential for industrial cables:

• Inorganic non-combustible structure: Withstands continuous operating temperatures exceeding 1,380 °F (750 °C for Phlogopite) and up to 1,830 °F (1,000 °C) during extreme peaks, retaining its insulating properties even after outer polymer compounds have been consumed by fire.
• High dielectric Strength: Prevents partial discharges and dielectric breakdown in conductors subjected to high electrical fields.
• Chemical and radiation resistance: Exhibits exceptional chemical inertness against solvents, industrial oils, UV radiation, and ozone aging.

Application in fire-resistant cable manufacturing (Circuit integrity cables)

In the design of fire-resistant cables (pursuant to international standards such as IEC 60331 or BS 6387), these inorganic tapes are applied directly over the metallic conductor prior to the extrusion of primary insulation and outer jacketing:

1. Residual ceramic barrier: During a fire, the material forms a protective ceramic layer that physically keeps energized conductors separated.
2. Continuous operation assurance: Allows critical circuits—such as emergency lighting, smoke extraction systems, and fire pumps—to remain functional for the duration required for evacuation and firefighting operations.

Textile reinforcement and line manufacturability

To apply mica electrical insulation efficiently in high-speed manufacturing processes, the vitrified film is laminated with high-strength technical textile backings, such as woven glass fiber or thermally stable synthetic films:

• Mechanical support: The textile backing provides the tensile strength needed to prevent wrinkling or snapping during high-speed lapping.
• Flexibility and uniform overlap: Enables a consistent, homogeneous overlap percentage around the conductor, ensuring continuous dielectric coverage without unnecessarily increasing the cable’s overall outer diameter (OD).

Key industrial applications

This specialized component is essential in sectors where functional safety and thermal resistance are critical priorities:

• Transit infrastructures and underground railway systems.
• Petrochemical plants, refineries, and offshore platforms.
• Power distribution networks in foundries, steel mills, and high-temperature industrial plants.
• Safety and emergency wiring in high-occupancy commercial and industrial buildings.

FAQS

Unlike flame-retardant cables designed merely to prevent flame propagation, 2-hour fire-rated cable assemblies must survive extreme thermal stress followed by severe mechanical impact. Achieving compliance with stringent U.S. standards relies heavily on specialized inorganic barriers and technical textile substrates.

Thermal and mechanical demands: UL 2196 vs. International standards

In the United States, Underwriters Laboratories (UL) sets the industry standard through UL 2196 (Standard for Tests for Fire Resistance of Circuit Integrity Cables), widely considered one of the most demanding fire tests globally.

The UL 2196 2-Hour fire test

• Extreme Thermal Exposure: The complete cable system is installed in a furnace following the ASTM E119 time-temperature curve, reaching temperatures exceeding 1,850 °F (1,010 °C) over a 2-hour period while energized at rated operational voltage.
• Hose-Stream Impact Test: Immediately following the 2-hour burn, the glowing assembly is subjected to a high-pressure fire hose stream.
• Pass/Fail Criteria: The cable must withstand severe thermal shock, rapid cooling, and kinetic force from the water blast without short-circuiting or losing electrical continuity.

The critical function of technical textile substrates and fire barriers

During the initial minutes of a high-temperature fire, outer polymeric jacketing and primary insulation (such as XLPE or PVC) completely decompose. At this stage, cable survival depends entirely on the inorganic protective layers wrapped around the conductors.

1. Residual inorganic dielectric shield

High-temperature mineral tape applied directly over the conductor acts as a ceramic shield. Capable of withstanding temperatures exceeding 1,830 °F (1,000 °C) continuously, these inorganic layers maintain essential dielectric strength and physical separation between conductors when organic materials have burned away.

2. Woven glass fiber backing for structural resilience

Passing the severe hose-stream portion of UL 2196 requires exceptional mechanical strength. Lamination with woven glass fiber substrates provides vital structural integrity:

• Thermal Shock Resistance: Prevents the vitrified protective layer from flaking, cracking, or washing away under high-pressure water impacts.
• High-Speed Lapping Efficiency: Delivers the high tensile strength required for continuous, high-speed wrapping operations on cable manufacturing lines without breaking or wrinkling.

Low-smoke zero-halogen (LSZH) compatibility

Modern commercial and industrial specifications frequently pair UL 2196 circuit integrity requirements with Low-Smoke Zero-Halogen (LSZH) outer jacketing. The inorganic substrates and technical textile backings supplied by Juan Gili S.L. are chemically inert and fully compatible with clean extrusion compounds, helping prevent the release of toxic gases or dense smoke during a fire event.

Primary industrial and commercial applications

UL 2196 fire-rated CI cable assemblies are specified in high-risk environments throughout North America:

• High-rise commercial, residential, and healthcare structures.
• Underground transit tunnels and railway infrastructure.
• Oil & gas refineries, petrochemical plants, and offshore rigs.
• Power generation stations, industrial foundries, and data centers.

FAQS

Technical summary :

• Material: 100% natural cotton; non-conductive and non-abrasive.
• Primary Function: Fills internal voids, maintains a circular cross-section, and manages internal moisture.
• Impact: Increases resistance to torsion, compression, and mechanical fatigue in low/medium voltage and control cables.

What are cotton filler cords?

Cotton filler cords are specialized cotton ropes designed to fill the interstitial spaces between the conductors of an electrical cable. Their primary function within the cable’s architecture is to maintain its circular geometry, prevent internal elements from shifting under mechanical stress, and provide structural cohesion during manufacturing, storage, and installation.

Made from 100% natural cotton fibers, these cords offer the high flexibility, tensile resistance, and adaptability required across various diameters and complex configurations.

Why are they important in electrical cables?

A high-quality filler material is vital to ensuring mechanical integrity over the operational lifespan of the cable. Cotton filler cords deliver multiple performance benefits:

• Stable internal structure: Prevents conductors from shifting, crossing, or deforming, which could otherwise compromise electrical performance and impedance.
• Greater compression and torsion resistance: Absorbs and distributes mechanical stress during laying and installation, especially along complex routes.
• Compatibility with insulation materials: Seamlessly integrates with standard jacketing materials such as PVC, polyethylene (PE), rubber, and LSZH compounds.
• Superior cable finish: Ensures a regular, uniform profile, simplifying stripping, connectorization, and spooling operations.

Typical industrial applications

Due to their versatility and mechanical behavior, cotton filler cords are widely utilized in the production of diverse electrical wire types, including:

• Low- and medium-voltage power cables.
• Industrial control and instrumentation lines.
• Multipair or multiconductor configurations.
• Residential and commercial installation wires.
• Flexible cords and braided designs subject to continuous movement.

Advantages over synthetic filler materials

Although alternative synthetic fillers like polyester, polypropylene, polyethylene, or polyamide exist in the market, cotton remains one of the most valued materials for several core reasons:

1. Natural behavior and softness: Minimizes internal friction in cables subjected to cyclic bending.
2. Moisture absorption capacity: Helps regulate internal microclimates without structural degradation.
3. Non-conductive and non-abrasive properties: Unlike certain stiff synthetic fibers, it protects both conductor insulation and outer jackets throughout the long service life of the asset.

Technical considerations for manufacturers

When selecting cotton filler cords, cable designers and manufacturers should evaluate key factors such as:

• Appropriate diameter and linear density according to the final geometry.
• Required twist or braiding level to ensure dimensional stability under tensile loads.
• Density and moisture behavior based on the target operational environment.
• Thermal compatibility with extrusion processes of insulation compounds.

A well-engineered core design can make a profound difference in final cable quality and field reliability. If your company is developing high-quality electrical cables and seeks effective, customized textile solutions, Juan Gili S.L. offers a comprehensive range of cotton filler cords manufactured to strict technical standards. Contact us to find the ideal option for your upcoming cable projects.

FAQS

In modern cable manufacturing, employing a specialized non-woven binding tape provides essential mechanical binding without introducing unnecessary bulk, excess weight, or rigid internal stress points.

The dual challenge: core splaying and thermal adhesion

When a cable bundle passes through the jacketing extruder, it encounters two severe processing threats that can jeopardize final product quality:

1. Mechanical de-bundling under High tension: High-speed line speeds exert considerable centrifugal and longitudinal forces on multi-core assemblies. Without a dedicated cable core binding tape, individual conductors can drift out of alignment, resulting in non-concentric profiles and variable jacket wall thickness.
2. Polymer fusion and jacket adhesion: Molten outer jacketing materials—such as PVC, PUR, TPE, or XLPE—are applied at elevated processing temperatures. Direct contact between the hot molten polymer and primary conductor insulation can cause thermal degradation or unwanted bonding, making field stripping exceptionally difficult.

Applying an engineered cable core binding tape forms an impermeable mechanical and thermal barrier, shielding internal components while preserving smooth jacket separation during installation.

Key technical properties of non-woven and reinforced binding tapes

Selecting the correct binding substrate depends on mechanical tension requirements, short-term thermal exposure, and dielectric specifications. Engineered polyester and nylon tapes offer distinct operational advantages:

Reinforced variants utilizing high-tenacity (HT) polyester yarn grids achieve tensile breaking loads exceeding 120 N/cm. This structural reinforcement ensures that the cable core binding tape holds heavy-gauge conductors in a tight circular geometry under demanding manufacturing conditions.

Compliance with international manufacturing standards

Industrial power cable designs must adhere to strict international quality frameworks, such as IEC standards for electric power cables. These standards govern core compactness, insulation integrity, and thermal endurance. Utilizing a high-purity non-woven binding tape ensures that internal assemblies maintain uniform cross-sectional geometry, meeting rigorous factory acceptance testing (FAT) requirements.

Furthermore, delivering tapes on high-capacity pad spools and jumbo spools (with outer diameters up to 600 mm) substantially reduces production downtime by extending continuous taping runs on automated cabling lines.

Primary applications across industrial cable families

High-performance binding and separator tapes are specified across diverse cable architectures:

• Low and medium-voltage power cables: Binding conductors and core assemblies prior to metallic shielding or outer armoring.
• Continuous-Ffex control cables: Creating a low-friction internal interface that allows free core movement inside drag chains.
• Armored & subsea cables: Providing heavy-duty mechanical separation and dimensional containment under high-pressure extrusion.

FAQS

Europe’s energy islands

Spain and Ireland share a structural problem that few other EU members face: both are classified as “energy islands” by the European Commission. Despite generating large surpluses of renewable electricity—solar in Spain, offshore wind in Ireland—neither country has enough cross-border interconnection capacity to export those surpluses efficiently.

For Spain, the bottleneck has a name: France. The Pyrenean mountain range limits interconnection capacity to roughly 3,000 MW, representing only around 2% of Spain’s installed generation mix—well below the EU’s minimum target of 10% and far short of the 15% target for 2030.

The agreement: a memorandum of understanding

In April 2026, during the WindEurope 2026 congress held in Madrid, Spain and Ireland signed a Memorandum of Understanding to study the feasibility of a submarine electricity interconnector between the two countries. The agreement was signed by Spain’s Vice President Sara Aagesen and Ireland’s Minister Darragh O’Brien.

The MOU is the first formal step in a process that will now involve joint technical and economic evaluation by Red Eléctrica de España and EirGrid, the two national grid operators. The project would subsequently be submitted to European authorities for potential inclusion in the Projects of Common Interest list.

Technical overview: what the cable would look like

The projected route would connect the northern coast of Spain—specifically Asturias—with the southern coast of Ireland, spanning an estimated 1,000 to 1,100 kilometres. Along the way, the cable would cross significant depths in the Bay of Biscay and the Celtic Sea.

The technology of choice is High-Voltage Direct Current, the industry-standard solution for long-distance submarine interconnections. HVDC systems transmit electricity with significantly lower losses than alternating current over long distances, making them the only viable option at this scale.

The cable would require substantial onshore reinforcement as well. In Spain, the Cantabrian mountain range would need to be crossed to connect Asturias with the main solar generation hubs in the interior of the peninsula.

The energy logic: solar meets wind

The project’s underlying rationale is the complementarity of the two countries’ renewable energy profiles. Spain produces large volumes of solar electricity during daylight hours and in summer months. Ireland, driven by Atlantic weather systems, generates significant amounts of offshore wind energy.

These two generation profiles are naturally decoupled. A bidirectional cable between them allows each country to act as a buffer for the other: Spanish solar can power Dublin when the sun is shining, while Irish wind can sustain Spanish industry when Atlantic storms sweep the north.

Investment scale and timeline

A submarine cable of this length and capacity represents a major infrastructure investment. Preliminary estimates place the total cost at between €2,000 and €3,000 million. Construction, once approved, would take several years.

The project is currently at its earliest stage: the MOU commits both sides to study feasibility, not to build. From here, REE and EirGrid will conduct joint technical assessments before presenting findings to European institutions.

Why cables remain central to the energy transition

Projects like this Spain–Ireland interconnector illustrate something that is easy to overlook in discussions about renewable energy: the physical infrastructure underneath still matters enormously.

Submarine cables are complex, highly engineered systems that must withstand extreme pressure, saltwater corrosion, mechanical stress, and the need for long-term reliability with minimal maintenance access.

The components that make cables safe, durable, and functional—water-blocking elements, insulating tapes, filler cords, reinforcing yarns, mica layers—are not incidental details. They are what allow a cable to perform reliably for decades on the seabed.

JGili and the future of cable infrastructure

At Juan Gili S.L., we have been supplying specialist cable components to manufacturers across Europe for decades. We understand the technical demands that projects like this place on every element of the cable system.

The Premier Global Event for the Wire and Cable Industry

Wire Düsseldorf is recognized worldwide as the leading exhibition for the wire and cable sector, bringing together manufacturers, suppliers, and industry professionals from across the global market.

Dates & Venue

• April 13–17, 2026
• Messe Düsseldorf, Germany

About wire Düsseldorf

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Our Participation at wire 2026

At this year’s edition, we will present our latest innovations.

Stand Information

• Hall: 13
• Stand: A61

Why Visit Our Stand?

• Explore our most recent advancements
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Planning Your Visit

We recommend arranging meetings in advance.

We Look Forward to Welcoming You

Join us from April 13–17, 2026.

In February 2026, the European Commission responded with its most concrete action yet: €347 million in new funding, a Cable Security Toolbox, and a formal list of priority cable projects across the continent.

Why now? The threat landscape has changed

Between 2023 and 2025, a surge of submarine cable disruptions affected several EU member states—Germany, Finland, Lithuania, Sweden, and Latvia among them. Some incidents were attributed to accidents; others raised serious concerns about deliberate sabotage.

The EU had already signalled its concern a year earlier with a Joint Communication on cable security. By October 2025, a dedicated Cable Expert Group published a comprehensive EU risk assessment on submarine cable infrastructures, identifying specific threats, vulnerabilities, and dependencies. The February 2026 announcement translates that assessment into action.

The Cable Security Toolbox: a structured response

The toolbox is a coordinated framework developed jointly by the European Commission and member states through the Submarine Cable Infrastructure Expert Group. It sets out six strategic measures and four technical and support measures designed to improve cable security at every stage—before, during, and after an incident.

The framework covers the full resilience cycle: prevention, detection, response, recovery, and deterrence. It is intended to give member states and cable operators a common approach to risk, replacing fragmented national responses with coordinated EU-level action.

Cable Projects of European Interest (CPEIs)

Alongside the toolbox, the Commission published a list of 13 Cable Projects of European Interest. These are priority cable routes and systems identified as strategically important for EU connectivity and resilience over the next 15 years.

The CPEI designation guides public funding decisions and signals to investors and operators where EU support will be concentrated. Projects on the list will be eligible for dedicated funding calls in 2026 and 2027, totalling €267 million under the CEF Digital programme.

How the €347 million will be spent

The Commission amended the CEF Digital multiannual Work Programme (2024–2027) to redirect €347 million towards submarine cable projects. The funding is structured around three main areas:

• Cable repair capacity: two calls worth €60 million in 2026 to finance adaptable repair modules pre-positioned at ports or shipyards across EU sea basins, starting with the Baltic.
• SMART cable systems: a €20 million call for sensors and monitoring components integrated directly into submarine telecom infrastructure to gather real-time oceanographic and seismic data.
• CPEI funding: two calls in 2026 and 2027 totalling €267 million to support the construction and reinforcement of priority cable routes.

The repair module call is open exclusively to public bodies with an emergency response mandate—civil protection agencies, coast guards, navies, and national emergency response organisations.

A broader commitment: €533 million across the programme period

The February 2026 package does not stand alone. Under the full CEF Digital multiannual Work Programme for 2024–2027, a total of €533 million is allocated to submarine cable projects. Of that, €186 million had already been awarded to 25 projects before this announcement. Between 2021 and 2024, the EU invested €420 million in 51 backbone cable connectivity projects.

The scale of this commitment reflects a fundamental shift in how European institutions think about cable infrastructure—not as commercial telecoms, but as critical national and continental security infrastructure.

What this means for cable manufacturers and suppliers

Investment at this scale creates demand across the entire cable supply chain. New cable construction, repair modules, SMART monitoring systems, and the reinforcement of existing routes all require high-performance components that meet exacting specifications.

The cables that connect Europe’s coasts must withstand extreme pressure, saltwater corrosion, and mechanical stress over decades—with minimal opportunity for maintenance. Every material choice, from insulating tapes and water-blocking elements to reinforcing yarns and filler cords, has a direct impact on cable reliability and service life.

As EU funding accelerates deployment across the Baltic, Mediterranean, and Atlantic sea basins, manufacturers supplying this infrastructure will face increasing pressure to demonstrate that their components meet the most demanding standards.

JGili and the future of submarine cable infrastructure

At Juan Gili S.L., we have spent decades supplying specialist cable components to manufacturers across Europe. We understand the technical demands that critical infrastructure projects place on every element of a cable system—and we know that in submarine applications, there is no margin for compromise.