Resin Cable Joint Kits (Medium Voltage)

Renewable grids, urban networks and industrial installations increasingly depend on medium voltage cable joints that remain reliable in wet soil, flooded trenches and long‑life underground routes. Cable failures after water exposure are most often concentrated at accessories such as joints and terminations, not the cable itself.

This page explains what resin cable joint kits are, why resin joints are still widely used in medium voltage (MV) applications, how to select the right solution, and how Lovink connects you to two proven MV joint families that use our own polyurethane resin Protolin®.

Explore Lovink MV joints with resin protection:

A resin cable joint kit is a jointing system where a two‑component resin is mixed and poured (or injected) into an outer housing or mould to provide:

• Environmental sealing (moisture barrier)
• Mechanical protection (impact, soil movement, incidental excavation contact)
• Secondary electrical insulation under wet conditions
• Long‑term interface sealing at cable sheath and component transitions

In medium voltage jointing, resin is typically used as the outer encapsulation and sealing barrier around the inner electrical insulation system.

Resin is selected in MV networks because water ingress tends to start at interfaces and accessory systems. Once moisture enters a joint, degradation mechanisms can follow (insulation resistance reduction, higher dielectric losses, partial discharge initiation, accelerated ageing).

Lovink’s polyurethane resin Protolin® is engineered and validated as a system‑critical sealing barrier for MV joints, supporting resistance against hydrostatic water pressure up to 2 bar (~20 m water head) when used as part of the joint system.

Key reasons utilities and contractors still specify resin jointing solutions in MV:

• Moisture resistance & sealing performance in wet soil and flooded trenches
• Low viscosity during casting enabling cavity filling (void avoidance is critical)
• Mechanical robustness after curing (protects the joint body in underground service)
• Long‑term ageing stability under thermal and hydrothermal exposure

Resin jointing solutions are commonly applied in:

• Underground MV distribution networks
• Renewable energy grid connections (wind, solar, storage)
• Industrial MV installations with harsh soil or chemical exposure
• Flood‑prone areas and high groundwater regions

In these environments, joint performance does not only affect technical reliability, but also outage frequency, repair interventions and asset lifetime. In flood‑prone and high‑groundwater areas, repeated joint failures can significantly increase maintenance effort and total cost of ownership.

For context on MV joint reliability and test approaches, see independent literature on MV cable joint testing trends.

When selecting a medium voltage resin cable joint kit, focus on:

1) Network & voltage class

• Typical MV systems: 6–36 kV class (project‑dependent)

2) Cable type & construction

• XLPE / EPR / polymeric insulated
• PILC / paper insulated (transition requirements may apply)

3) Environment

• Wet soil / flooding risk
• Limited access routes (long repair times)
• Potential chemical exposure

4) Installation and risk control

• Ability to achieve void‑free encapsulation
• Controlled working time (pot life)
• Documented installation procedure + trained installers

Not sure which solution fits your project?

Use our product selection tool to enter your cable details and installation environment and find the correct MV joint configuration.

Resin jointing is not the only MV technology. Selection depends on application.

Resin joints 
Best when: wet environments, mechanical protection priority, interface sealing critical.

Cold‑shrink joints
Best when: fast installation, no flame, consistent radial pressure, confined spaces (technology category overview).

Heat‑shrink joints
Best when: proven standard approach, but installation quality depends strongly on installer technique and heating control.

MV cable joints are commonly evaluated using standardized testing approaches such as IEEE joint standards.

In Lovink MV cable joints, Protolin® forms the outer encapsulation and environmental sealing barrier, supporting:

• Continuous watertight barrier
• Adhesion‑based sealing at interfaces
• Mechanical stabilization of the joint body
• Secondary electrical insulation under wet conditions

For a practical explanation of why polyurethane resin remains the standard for cable joint protection, see:

• Why polyurethane resin is the best standard for cable joint protection

LoviSil® M Series
Liquid silicone insulation combined with Protolin® resin outer sealing. Ideal when flexible insulation and advanced interface control are required.

Whether you are still evaluating your options or have already selected a joint family, we’re here to support your next step, from technical discussion to pricing and availability.

What is a resin joint?
A resin joint is a cable joint where a two‑component resin is cast into a housing to seal and protect the connection against moisture and mechanical stress. 

Are resin cable joint kits waterproof?
Water resistance depends on resin formulation, interface sealing and installation quality as part of the total joint system. 

Can resin cable joint kits be used in flooded trenches?
Yes, resin joint kits are commonly specified for wet soil and flood‑prone environments when correctly selected and installed. 

How do I choose the right resin cable joint kit?
Selection depends on voltage class, cable type, environment and installation constraints. Use the selection check for a fast recommendation.