Cable duct sealing systems

Roxtec UG™ (underground) seals are mechanical duct seals. They are engineered for cables passing through underground ducts into buildings, substations or enclosures.

What is a cable duct seal – and why does it matter?

Roxtec cable duct seals are used for underground cable-entry sealing in basements, foundations, electrical substations, and field cabinet applications. They are also used in manhole and vault applications for duct bank and cable entries. The seals protect switchgear buildings, transformer cabinets, SCADA systems, and field junction boxes against humidity, water ingress, flooding, gas, fire and vermin. Duct sealing systems are crucial for protecting vital equipment and for ensuring long-term operational reliability. Without proper duct sealing, you risk damage, downtime and costly repair work.

Roxtec cable duct seals for multi-hazard protection  

With Roxtec duct seals, you can protect your site from multiple hazards. You can prevent groundwater ingress and surface flooding and thereby avoid switchgear damage and power outages. Avoiding humidity and moisture is also a way of preventing partial discharge (PD) activity, which is a frequent cause of switchgear failure.

You can block duct entries from becoming fire pathways. You prevent flames from spreading from one compartment to another and can easily meet strict fire safety requirements. You can also ensure your facilities meet DSEAR requirements regarding migration control of gases such as methane, H₂S or hydrocarbons.

In addition to this, Roxtec cable duct seals form a barrier against rodents. This helps you protect cable insulation and electronic equipment and reduce the risk of disruption.  

7 reasons for choosing a mechanical cable duct seal

There are several reasons for selecting mechanical modular-based duct seals from Roxtec instead of mastic, putty or compound-based products. There is a thorough comparison between modular-based and wet-applied solutions available if you click here.

Here is, however, a summary of reasons for choosing the Roxtec duct seal option:

1. Roxtec duct seals are openable. With re-enterable seals, you can remove or add cables at any time, without tools. You do not need to break or replace anything.
2. Multidiameter™ by Roxtec. The sealing modules in the duct sealing system are easy to adapt to cables of different sizes thanks to removable rubber layers.  
3. Roxtec duct seals do not need any curing time. They are operational immediately after installation.
4. It is dry and clean to install Roxtec duct seals. You do not need any solvents.  
5. Roxtec duct seals have a long service life and do not degrade, shrink or crack over time.
6. Roxtec duct seals provide built-in spare capacity. You can plan for future cables and further expansion already from the start.  
7. Roxtec duct seals are certified. They comply with WIMES, DSEAR, ATEX and ENA-ER G17/3 requirements and simplify verification of installation quality and performance. 

Duct sealing systems for various industries

As Roxtec supplies fire resistant, gas-tight and watertight duct seals, the solutions cover protection needs and safety requirements within several sectors, including:

• Power transmission and distribution. DNOs (distribution network operators) and T&D contractors use Roxtec duct seals for high-voltage and medium-voltage cable entries into substations and switch rooms. The seals comply with ENA-ER G17/3.
• Solar farms. Roxtec duct seals are often specified for DC collection cables and HV export cables for kiosk and substation entries to avoid the risk of flooding.
• Onshore wind power. The duct seals are ideal for new-builds as well as retrofits of turbine base and site substation entries, protecting against water ingress.
• Datacentres. Roxtec duct seals manage the challenge of densely populated HV and LV entries into data halls as they are re-enterable and offer spare capacity.
• Rail infrastructure. In traction power substations and lineside equipment, DSEAR compliance is typically required. Therefore, it is sound using Roxtec duct seals.
• Industrial and processing facilities. Roxtec Ex rated duct seals handle hazardous area zones within pharmaceutics, semiconductor fabs, oil and gas, ports and airports.  

What regulatory standards do Roxtec duct seals comply with?

Roxtec cable duct sealing systems comply with the following UK regulatory standards:

• WIMES 3.02 2019 – the water industry standard that is accepted by all major UK water authorities.
• ENA-ER G17/3 – the Energy Networks Association standard that governs flammable gas leakage at substation duct entries and applies to all DNO and T&D substation work.
• DSEAR 2002 – the Dangerous Substances and Explosive Atmospheres Regulations that require gastight duct seals where flammable gas migration is a risk.
• ATEX/IECEx – the certification for Zone 1 and Zone 2 classified areas that is required on Ex rated sites.

Remember to always let a project engineer or a DNO confirm applicable requirements.

Roxtec UG™ duct sealing solutions

Roxtec UG™ (underground) seals are developed for cable duct sealing. You can seal around a single cable as well as multiple cables of varying sizes in a duct. The seals can be used for efficient multi-hazard protection in new builds as well as in retrofit projects.

The Roxtec R UG™ is a round transit for multiple cables entering via ducts or foundations. The duct sealing solution provides flexible configuration for cables. 

The Roxtec RS UG™ is a round seal designed for single cables entering buildings via ducts or foundations. The compression is integrated in the duct seal.

The Roxtec H3 UG™ is a round seal designed for 11kV and 33 kV power cables in trefoil formations. The duct seal design simplifies retrofit installations.

• Easy to install even in running water conditions
• Adapt to cables and ducts of different sizes
• Built-in spare capacity for additional cables
• Withstand pull force and extreme bending force
• Withstand constant water and catastrophic water pressure
• Protect against gas pressure and rodents

How to install a Roxtec duct seal

Roxtec cable duct seals are easy to install. User-friendly installation instructions are provided with each specific product, but here is a simple four-step process overview:  

1. Define the duct entry. Precise the duct diameter, the number of cables and their outer diameters (OD) as well as the protection that is required.
2. Select Roxtec UG™ transit or seal. Choose the right format for the duct geometry.
3. Adapt the seals. Peel off layers from the sealing modules or rubber bodies with Multidiameter™ to match each cable OD. You can spare modules for future capacity.
4. Compress the sealing solution. There is no curing time, and you can always re-enter.