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WIMES Compliant Duct Seals & Sealing Systems

WIMES Compliant Duct Seals & Sealing Systems

What is WIMES?

The Water Industry Mechanical and Electrical Specifications (WIMES) define the requirements for a wide range of mechanical and electrical equipment used in the UK water industry.

The Purpose of WIMES
The purpose of WIMES is to provide a consistent and uniform set of guidelines and requirements for the design, installation, and maintenance of mechanical and electrical equipment used in water and wastewater treatment plants, pumping stations, and other water-related infrastructure.

WIMES cover a wide range of mechanical and electrical equipment used in the water industry, including pumps, motors, valves, control systems, instrumentation, and other components. The specifications aim to ensure that equipment used in the water sector meets certain quality, performance, and safety standards, helping to maintain reliable and efficient operations across the industry.

WIMES are regularly updated to reflect advancements in technology, changes in regulations, and lessons learned from operational experience. These updates ensure that the standards remain relevant and effective in improving the overall performance and sustainability of the water industry.

It's essential to note that the information provided here is based on the state of knowledge up until 2019 and there might have been updates or changes to WIMES beyond that date. Therefore, for the most current and accurate information, I recommend consulting official sources or relevant organisations involved in the water industry in the UK

Current Water Authorities that are members of WIMES:
The WIMES have been produced with the co-operation and approval of the following water companies:

  • Affinity Water
  • Anglian Water
  • Bristol Water
  • Cambridge Water Company
  • Irish Water
  • Northern Ireland Water
  • Northumbrian Water
  • Scottish Water
  • Severn Trent Water
  • South East Water
  • South West Water
  • Thames Water
  • United Utilities
  • Veolia Water
  • Welsh Water
  • Wessex Water
  • Yorkshire Water

How Does AC Cable Solutions use WIMES
We take great pride in adhering to the WIMES specification at AC Cable Solutions, as our Duct Sealing products play a vital role in numerous water authorities across the UK & Ireland. Each of our Duct Sealing products, whether manufactured or distributed by us, is carefully designed to meet and exceed the rigorous requirements set forth by WIMES. This commitment ensures that our products are not only of the highest quality but also fully compliant with industry standards. By upholding WIMES' guidelines, we aim to contribute to the efficient and reliable operations of water infrastructure while maintaining the utmost dedication to quality, safety, and customer satisfaction.

Where are ducts sealed on Waste water Treatment Works/Sites?
On a WWTW (Wastewater Treatment Works) site, cable ducts are typically sealed with duct seals at various crucial locations to ensure proper functionality and safety. Some common areas where cable ducts are sealed include:

Electrical Control Rooms
Cable ducts carrying power and control cables entering and exiting electrical control rooms are sealed to protect sensitive electrical equipment from environmental factors like water, dust, and pests.

Motor Control Centres
(MCCs): MCCs house motor starters and other electrical components. Cable ducts leading to and from MCCs are sealed to safeguard the electrical connections and maintain the integrity of the motor control system.

Instrumentation Panels
Cable ducts containing cables for instrumentation and monitoring devices are sealed to prevent water ingress and ensure accurate data collection.

Pumping Stations
In pump stations, cable ducts are sealed to safeguard the electrical connections of pumps and control systems, as well as to prevent potential hazards and equipment damage.

Distribution Boards
Cable ducts leading to distribution boards are sealed to maintain the electrical distribution system's efficiency and to protect against electrical hazards.

Communication Rooms
Cable ducts used for network and communication cabling are sealed to maintain reliable communication between different sections of the WWTW site.

UV Treatment Units
In areas with ultraviolet (UV) disinfection systems, cable ducts are sealed to protect the electrical components from moisture and ensure the continuous and effective operation of the UV units.

Properly sealed cable ducts contribute to the overall functionality, reliability, and safety of the WWTW site by preventing potential electrical failures, equipment damage, and operational interruptions caused by environmental factors.

How & Why does AC Cable Solutions comply with the WIMES Specification?There are sections within the WIMES guidance/specification that advise on best practices and product technology that should be used on a WWTW site. – Let's break this down:

Within WIMES 3.02 - 2019
The Type of sealing systems used shall be approved by the purchaser and shall be selected and installed with regard to environmental and hazardous area requirements(refer to WIMES 3.02 (D)). The type of sealing systems used shall be selected from the following options:

a). Approved water, gas & fire sealing transits with fillers and insert blocks fitted to suit all cables and conduits.

This description of this technology refers to cable Transit sealing systems with rubber modular blocks such as Hawke HTS transit sealing systems, which is a means of sealing cables and pipes passing through a wall, floor or bulkhead.

The Hawke Cable Transit Sealing System will seal against and exhibit resistance to: 

  • Fire
  • EMC
  • Water
  • Radiation
  • Gas
  • Chemicals
  • Explosion
  • UV
  • Smoke
  • Vermin, &
  • Noice

To find more information about the Hawke HTS Transit seals, for circular or rectangular penetration, please contact the following: 

Hawke HTS Transits 
Steve Groocock - Regional Sales Manager 
Tel: 07473 239254

b). Approved fire retardant (if required) and gas & watertight sealing system, comprising insert sleeves to ensure cable separation and silicone-based sealant.

Recently there has been a change to this spec.
The word (if required) has been added so if fire resistance isnt required (which is the case for the majority of duct-sealing applications), then a non-fire-rated version of the sleeve system can be used leading to significant cost savings.

The use of the insert sleeves within duct sealing kits, aids installation when larger cables are installed within ducted networks. These sleeves are tubular shaped and made from a polymer with a rubber feel & texture. AC Cable Solutions has a sleeve system called Duct Seal HG that isnt fire resistant, but can now be used on non fire applications. 

Duct Seal HG is a duct & penertraition sealing systems that provides enhanced durability, offering up to 2 Bar resistance to water, gas, and air pressure. It is specifically designed to separate & support larger cables. The circular backing tubes can be interconnected to form a cross-piece for trefoil/triplex cables or a collar for quickly supporting single cables or pipes. The circular tubes can also be joined in groups of 5, split, compressed, or used as a whole unit to achieve a strong support around singular or multiple cables. 

  • One-of-a-kind patented trefoil/triplex cable separation - The best in the marketDuct Seal HG
  • MEKO-free, Fybrid, Non-Hazardous Intumescent sealant
  • Water & Gas Tight
  • Resists Toxic Gases: Hydrogen Sulphide, Chlorine Gas, & Methane - Perfect for the Water Industry
  • Resists Hydrocarbons - Perfect for the Petrol Forecourt industry
  • Microbial Défense - boosted to resist fungi & bacteria
  • MADE IN UK - All components are designed and manufactured locally


Before installing a fire-resistant seal, it is crucial to assess the technology category in question thoroughly. Determine whether a fire-resistant seal is genuinely necessary for your specific application. Additionally, ensure that the ducts and cables meet the required fire-resistant standards.

A good annology is: Placing a fire-resistant door on a cardboard house and rendering the safety measures ineffective. 

Watch this Space – Duct Seal FR coming very soon.

c). Approved Fire retardant and gas and water sealing system, comprising an expanding, two-component polyurethane resin formulation, which cures into a high-density, hydrolysis-resistant compound.

High-quality expanding resin seals ducts effectively but is challenging to remove. Its use has declined on WWTW sites, favouring more accessible sealing methods. However, it remains valuable for situations requiring long-term, undisturbed sealing.

d) . Approved gas & watertight sealing system comprising flexible, interlocking foam inserts to ensure cable separation and a silicone-based sealant

This technology description is the one most referred to on WWTW sites. Most ducts require sealing against gas & water tightness but strictly adhere to a seal that can resist water, hydrogen sulphide, chlorine gas, and various hydrocarbons.

This technology matches our product, called Duct Seal LG, which uses a unique foam that is tubular shaped, that interlocks, but also aids the curing speed and eliminates slump. The sealant that’s included in this duct sealing kit GreyStuff, uses the latest FyBrid technology, creating a superior single-component, ZERO MEKO, non-hazardous,  neutral curing sealant that has been specifically developed to cope with the harsh environments around duct openings to ensure ducted networks and penetrations are protected.

Duct Seal LG provides the following:

  • Revolutionary circular foam backing system
  • MEKO-free, Fybrid, Non-Hazardous Intumescent sealant
  • Water & Gas Tight
  • Resists Toxic Gases: Hydrogen Sulphide, Chlorine Gas, & Methane - Perfect for the Water Industry
  • Resists Hydrocarbons - Perfect for the Petrol Forecourt industry
  • Microbial Défense - boosted to resist fungi & bacteria
  • MADE IN UK - All components are designed and manufactured locally.

To find more information about DuctSeal LG please Click Here

When choosing a sealing system, using the information above from 3.02 2019, the water authority / contractor must also make sure the sealing system complies with WIMES 3.02 (D) Issue 1 – Electrical Installations in Hazardous Areas.

Within 3.02 (D), it states
All sealing systems used shall comply with the following performance as a minimum.

  1. They shall be gas & watertight to a minimum pressure of 1 bar; and
  2. They shall be resistant to corrosion /degradation in the relevant operating environments.

All sealing systems suppliers/manufacturers must be able to provide documentary evidence relating to the above performance requirements to the purchaser on request.

All sealing systems from AC Cable Solutions meet the requirements of 3.02 (D), and should you wish to receive documentary evidence, please contact technical using the following email address:

Please note: Other sealing systems may be available from other sources. 


Written by Carl Pike - The Duct Sealing Man 

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