CABLE MANAGEMENT
BSEE
Specifying for success: Choosing the correct cable specification
With so many cable protecon systems now available, it can seem a complex task to specify the right product for the applicaon. Should installers select based on the likely temperature range, exposure to UV radiaon, resistance to chemicals or for specific fire performance to name a few? Tim Creedon, from flexible conduit manufacturer, Flexicon, explains the steps that can be taken to ensure correct specificaon, assessing the wide variety of material types and properes now available
temperature, UV radiation, harsh chemicals and the likelihood of water or dust ingress. In addition, fire performance, compression strength and impact or abrasion resistance, risk of explosion or even the resistance to build up of bacteria should be considered. While many products may look the same, performance properties can vary greatly, so customers should always check suitability and compatibility for their application. Flexicon, for example, offers detailed comparative performance data on the 60 systems available, as well as ‘Flexiapp,’ a specialist smartphone app and online product selector. Such information is vital, as contractors can often choose solutions based on incomplete information, including outdated requirements, previous installation experience, or personal preference. This can lead to compromised cabling or dismissing a lower cost protective system due to over-specification.
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Choosing metal, nylon or composite conduit
One of the first areas to consider is whether to opt for non-metallic (nylon), metallic or composite flexible conduit.
Before the development of engineered plastics, conduits and conduit fittings were made of metal. As plastics developed, they were used as sheathings to provide increased flexibility, plus improved water and corrosion resistance. With the development of high-performance engineering polymers, all-plastic conduits were developed together with injection-moulded conduit fittings, with nylon polyamide (PA) being one of the most important materials now available.
Nonmetallic systems
With no exposed metallic content, non-metallic conduits do not rust or corrode, thus maintaining performance and appearance over time. They are often quicker to install than metallic options as they are easier and faster to cut. Non-metallic fittings will typically be one piece and simply push on and twist to secure.
Where fatigue life or impact resistance is important, installers should consider nylon polyamide (PA) corrugated flexible conduits,
pecifying cable protection based on one property alone can be a costly mistake and the full range of environmental factors should be considered. These can include exposure to extremes of
which can offer high impact strength and recovery if crushed combined with excellent temperature performance.
Polypropylene and PVC conduits are available, but their suitability is limited, with both of these systems being inferior to nylon polyamide (PA) when it comes to temperature range, fire performance, resistance to solvents and abrasion resistance. For installations subject to increased UV exposure, it is important to consider that ultraviolet (UV) radiation will naturally degrade any plastic materials. Failure could result in materials cracking, an increase in brittleness, reduced flexibility and lower impact strength.
Metallic and composite systems
Metallic systems are ideal for applications that require a very high compression or pull-off strength, or where there is the need to protect cables from exposure in hazardous environments. These systems typically have a higher level of crush resistance, high mechanical strength and can provide excellent EMC screening properties.
Composite products, such as plastic sheathing on metal conduits, metal over-braiding or metal threads on plastic fittings can also offer the ideal combination of light weight and high strength.
Retrofitting options
In existing applications, retrofitting cable protection has, traditionally, been a more complex task, with the installer required to pull existing cabling through the open end of a conduit system. Conduit system manufacturers are therefore developing enhanced retrofit options to make it easier and quicker to install cable protection. Flexicon, for example, offers its FPADS range of divisible corrugated conduits. Manufactured from two nylon (PA6) interlocking slit corrugated conduits, the construction allows existing cabling to be inserted laterally via a slit opening. The two open conduits then interlock to form a protected IP40 system around the cables.
This effectively means that the customer can wrap a flexible conduit around the cables retrospectively with minimal disruption. It is also important to consider the cable routing. Traditional split conduit options can potentially expose cabling when bent or routed around corners, whereas the FPADS option will maintain continuous protection of the cabling irrespective of orientation or routing due to its interlocking design.
uAlternave conduit materials are available on request
Bespokedesigned cable protection
For more complex application requirements, customers should speak to their supplier to discuss bespoke options.
These could include conduit supplied in non- standard or pre-cut lengths, in larger or smaller diameters, or with different thread termination or fitting options. Additionally, more complex requirements, such as altering performance characteristics to meet a certain temperature requirement, compression strength or abrasion resistance or to achieve a greater fatigue life may also be considered.
Flexicon offers a design prototype service which allows customers to see new cable protection concepts, before investing in a full system solution. The service also includes bespoke testing and the preparation of customer samples for field trial and analysis.
Flexicon products are designed, tested and manufactured in the UK and its team of engineers are working continuously on tomorrow’s cable protection solutions. Its research and development team works with customers and has the facility to create 3D printed solutions to prove customer concepts.
In conclusion
Installers should take time to consider all factors before simply selecting flexible conduit based on preference or previous installation experience, to avoid over specifying or introducing unnecessary cost. After all, cable protection should be designed to do just that; protecting processes, performance and people, so taking time at the specification stage can save time and money further down the line.
www.flexicon.uk.com
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www.bsee.co.uk sales@fscables.com 01727 840841 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2019 9
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