Conduit quality - the big issue

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Flexible conduit is often used in very arduous environments and if products don’t come up to scratch there can be disastrous consequences for the end user. Here Ian Gibson, chairman of the combined IEC & Cenelec Committee for Conduits and technical director of Flexicon, looks at the issues surrounding conduit quality and the importance of picking the right product for the job.

Good quality in the flexible conduit market is sometimes overlooked but low-cost inferior products often have inherent weaknesses that mean they can be problematic and costly to install, or can lead to their failure during service. Using cheaper, poorer quality products can be a false economy as higher installation costs combined with the potential cost of remedial work and associated wasted labour time on reworks can more than outweigh initial outlay.
No longer a threat
Low-cost flexible conduit imports have been a threat to the UK market for some time but the tide is turning and there is recognition by many wholesalers, specifiers and end-users that quality conduit systems are a worthwhile investment. Manufacturers understand the importance of margin and profit for wholesalers and in turn installers, but if quality is being compromised in order to achieve this then it can only be a matter of time until there is a disastrous result.
Flexible conduit plays a key role in cable management and is responsible for protecting some of the most vulnerable and potentially dangerous materials in a building environment. They need to shield important cabling from external damage while protecting personnel and property from dangerous electrical exposure.
The conduit will often be subjected to harsh treatment in very poor conditions, including extremes of temperature, physical damage, chemical corrosion and wetness so it is essential these products can meet high standards of strength, safety, durability and performance and provide reliable cable protection.
New requirements
Following the devastating Kings Cross disaster of 1987, where fumes from melting fixtures and cables contributed significantly to the number of fatalities, new requirements for zero halogen (HF) and low fire hazard (LFH) products have now been introduced.
LFH conduit systems are increasingly specified in many cabling applications in order to protect both staff and the general public in the event of a fire. Public buildings, retail outlets, high rise office blocks, hospitals and transport installations are all likely to require LFH conduit and, in certain incidences, fire services and even insurers are demanding these products to be specified.
High-risk environments such as the London Underground have even introduced their own stringent regulations for suppliers. The ‘Section 12’ requirements of LUL standard 2-01001-002 pertain to the fire safety performance of materials, ensuring conduits can be safely used by OEM’s and contractors supplying and working in the London Underground system. A wide range of Flexicon’s products have documented compliance with this standard and it’s advisable that customers operating in other sectors of the market where public safety is a key criteria should look out for this type of certification.
Potential problems
At Flexicon we define a LFH product as being ‘halogen free’ (no halogen acid gas emission which can destroy computer equipment and damage building structure), ‘highly flame retardant’ (products will prevent a fire or limit its development if one does start), ‘low smoke emission’ (personnel will be able to see their way to escape in the event of a fire) and ‘low toxic fume’ (personnel will not be overcome by dangerous fumes during their escape).
Some conduits – in particular cheaper versions – claim to be LFH but don’t offer all these properties which means they can be dangerous in high-risk environments where safety is crucial.
Metallic conduit is typically manufactured from stainless or galvanised steel. One of the potential problems with metallic conduit arises from the use of inferior quality steel, which in turn results in structural and performance issues. It can be prone to kinking when bent, which weakens the product, or have other defects such as poor welds that fail under pressure or sharp edges inside the conduit which can damage the cables inside.
Another issue is differing standards in the galavanising process. Higher specification galvanised steel conduit is hot-dipped after manufacture which means it boasts both internal and external heavy protection and provides the best anti-corrosive properties.
Meanwhile, pre-galvanised products – which are usually lower in cost – tend to corrode after a relatively short period when exposed to damp or moist conditions due to the absence of zinc protection on the internal walls.
Another concern stems from the application and thickness of the galvanised layer which may look ‘shiny’ but can begin to flake after only a short time in use. This may leave the product open to the elements causing it to corrode quickly as its protective layer will have been compromised.
Non-metallic conduit, typically manufactured from nylon or polypropylene mixes, also carries risks of failure if sub-standard products are selected.
Thin walls can cause conduit to snap, exposing the cabling inside, while poor quality material may be resistant to much smaller temperature ranges, making it prone to damage in extreme cold or heat. It is also common to experience difficulties with fittings, due to poor or inaccurate manufacture and non-complementary product ranges.
As so many problems can arise from the use of poor materials it’s worth thinking about the origination of the conduit you’re purchasing.
Benefits of UK manufactured conduit
UK production gives total control over quality while buying from abroad means sources of materials may not be well documented. UK manufacturers have onsite expertise in place to oversee manufacturing facilities. Production can be monitored to ensure the correct use of materials and processes which ultimately ensures that top quality conduit is produced.
However, the only way to ensure conduit is of a high quality is to make sure it has been independently tested to the relevant BS standard.
This means the BS standard is not only printed on the packaging but stamped on the products themselves, along with the name or trademark of the manufacturer.
The testing carried out is rigorous and designed to ensure compliant products have the correct construction and mechanical properties to make them safe and resistant to damage.
Look out for BS EN 61386 which is a worldwide standard developed by IEC (International Electrotechnical Commission) and Cenelec (European Committee for Electrotechnical Standardisation) and replaces the previous BS EN 50086 and IEC 61386.
Meanwhile, ISO 9001 compliance looks at quality management systems within business processes and the European RoHS (Restriction of Hazardous Substances) directive bans the placing on the EU market of new electrical equipment containing more than agreed levels of various hazardous substances.
The regulations may just seem like annoying hurdles but all legislation is there to improve quality within the industry. Flexicon products comply with all key standards and the company is also a member of Beama (British Electrotechnical and Allied Manufacturers' Association), which helps write the standards and implement the legislation.
It is important to demonstrate a commitment to safety and product quality in order to instil trust in customers and give them peace of mind.
Ultimately, high-quality products eliminate risk, both for yourself and your customers, and ensure the UK electrical sector remains respected in the global marketplace.