• • • CABLES & CABLING MANAGEMENT • • •
SIMPLIFYING RETROFIT CABLE PROTECTION
Alex Smith, technical director at flexible conduit manufacturer, Flexicon, identifies some of the areas to consider when specifying retrofit cable protection systems
W
hile cable protection is always easier to carry out during electrical installation, there are many scenarios where vital electrical cables need to be protected after they have been installed. This may be because the requirement is identified at a later stage, or where existing cable protection is worn, or damaged and new options need to be retrofitted. Retrofitting cable protection has traditionally been a complex and lengthy task, with the installer required to pull existing cabling through the open end of a conduit system.
Conduit system manufacturers have been offer- ing slit conduit options for some time, enabling in- stallers to wrap insert the existing cabling to avoid disruption. However, it is important to ensure that the choice of flexible conduit system continues to offer the appropriate levels of protection for the en- vironment and does not leave any areas of cabling or the installation exposed.
Divisible conduits, such as the new Flexicon FPADS range, allow existing cabling to be inserted laterally via a slit opening. This product consists of two open conduit profiles, which then interlock to form a protected IP40 system around the cables. It is also important to consider the cable routing. Traditional split conduit options can potentially ex- pose cabling when bent or routed around corners, whereas the newer, divisible conduit options will maintain more mechanical strength and continu- ous protection of the cabling irrespective of orienta- tion or routing due to their interlocking design.
TERMINATION AND FITTINGS
All cable protection should be specified as a com- plete end-to-end system, taking into account not only the flexible conduit used, but the range of ter- mination and fittings used too.
This can make it a cumbersome task to terminate cabling in a retrofit application, however, manu- facturers are now offering an improved range of options to make this easier.
Flexicon’s FPADS range for example. includes a hinged fitting and locknut, compatible with the 21mm size divisible conduit, to provide an easy and secure termination option.
PROTECTING NEW CABLING As well as considering retrofit options, specifiers may also be tasked with installing new electrical cabling at the same time.
In this scenario, there is a broader range of op- tions available and specification should take into account the range of external hazards that the cabling may be exposed to; whether that is to meet a certain IP rating, enhanced fire performance properties, resistance to chemicals or UV exposure to name a few.
The performance of cable protection solutions available on the market can vary greatly so custom- ers should always check suitability and compatibil- ity for their application.
NYLON, METAL OR COMPOSITE?
Where fatigue life or impact resistance is impor- tant, installers should consider nylon polyamide (PA) corrugated flexible conduits, which can offer high impact strength and recovery if crushed com- bined with excellent temperature performance. Polypropylene and PVC conduit systems are avail- able; however, both of these systems are inferior to nylon polyamide (PA) when it comes to fire perfor- mance, resistance to solvents and their abrasion resistance properties.
With no exposed metallic content, non-metallic conduits do not rust or corrode thus maintaining
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performance and appearance over time. In addi- tion, it is worth considering labour and installation time. Non-metallic systems 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. Metallic flexible conduit typically has a higher level of crush resistance, high mechanical strength and can provide excellent EMC screening properties. Metallic systems in particular are ideal for applica- tions that require a very high compression or pull-off strength, or where there is the need to protect ca- bles from exposure in hazardous environments. 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.
BESPOKE DESIGNED For more complex application requirements, cus- tomers 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 termina- tion or fitting options. Additionally, more complex requirements, such as altering performance char- acteristics to meet a certain temperature require- ment, compression strength or abrasion resistance or to achieve a greater fatigue life may also be considered.
ELECTRICAL ENGINEERING • SEPTEMBER 2021 29
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