GPT provides expert cable duct sealing solutions to prevent water and gas ingress, protecting critical infrastructure and ensuring compliance, reliability and environmental protection.
Cable Duct Sealing
GPT Environmental provides specialist duct sealing solutions to prevent water ingress into underground assets and cable entries. Our expertise covers both new construction projects and retrofit applications, using mechanical systems and mastic seals. We deliver effective sealing even in challenging conditions, including confined spaces, active water flow, and live cable environments.
In addition to water protection, our solutions can offer enhanced fire resistance, gas-tightness, rodent deterrence, and ease of future cable access. With a focus on compliance, reliability, and long-term performance, we are trusted providers of professional duct sealing services.
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What is
Cable Duct Sealing?
Cable duct sealing plays a critical role in protecting infrastructure from environmental damage, particularly by preventing water and gas ingress through underground cable entries. Although the issue of water ingress has long been recognized, its impact has only recently gained the necessary attention - especially in light of increasingly frequent and severe flooding events across the UK.
These events have highlighted the vulnerability of vital infrastructure such as electricity substations, many of which remain inadequately protected against rising groundwater levels. Poorly sealed cable ducts can allow water to infiltrate critical areas, leading to equipment failures and operational disruptions.
Effective cable duct sealing addresses these risks by creating a secure barrier that prevents water from entering substations, renewable energy sites, and other essential facilities. In doing so, it helps mitigate the risk of flooding-related outages, protects sensitive electrical equipment, and reduces the likelihood of contamination that could require hazardous waste disposal.
Cable duct sealing supports operational reliability by controlling internal humidity levels, thereby preventing faults such as partial discharge and switchgear malfunction. As such, it is a fundamental component of both environmental risk management and infrastructure resilience.
Since 2011, GPT has sealed cable entries in hundreds of substations, ensuring long-term protection against water ingress. We offer tailored solutions using mechanical systems and mastic sealants, adapting to site-specific conditions, including confined spaces and active water intrusion.
Our expertise installing cable duct sealing means we can achieve seals where other contractors have failed or have said the job could not be successfully completed. We also specialize in resealing failed duct installations and retrofitting seals where none were originally installed.
These systems expand into the cable/pipe entry to form a water and gas tight seal. The system provides a high level of cable retention even where ground conditions cause the cables to bend, putting pressure on the seal.
Mechanical systems handle constant water pressure and require solid, round ducts for proper installation. Their durability and adaptability make them a preferred choice for wind farms, solar farms, and critical infrastructure projects.
Whereas mechanical systems require the ducts to be in a good condition and (almost) perfectly round, the mastic type product can be installed in entries of any condition.This mastic sealant bonds to the cable and the duct wall and, when properly installed, forms and impermeable seal, leaving the duct water and gas tight.
Case Studies
Large-scale Facility Duct Sealing
Nov 2024
Food Manufacturing Facility Duct Sealing
May 2025
