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Cable handling

Understanding Cable Mechanical Properties for Successful Installation

To help ensure the safety and longevity of your installed cables, here are some key cable mechanical properties to note for a successful installation. • Cable Bending Radius• Maximum Pulling Tension• Sidewall Pressure Cable Bending Radius The cable bending radius is the minimum radius a cable can be bent to without damaging it. The smaller the bending radius, the greater the flexibility of the material. Knowing your cable’s minimum bending radius will help prevent damage during installation. Please refer to our article here if you need a reference table and an example of how it is calculated. To prevent overbending in cables, we recommend how a cable could be fed during your setup process. If you are planning to lay your cables overhead, onto a tray, for instance, we recommend mounting cable drums on jacks or cable stands in the orientation so that the cable can be pulled from the top. This is the default recommended orientation for pulling cables rather than from the underside; to prevent the cable from potential damage due to overbending or friction against the ground, especially when possible sharp objects such as rocks or nails are on site. Setup for overhead However, if you are installing the cable in a duct close to the ground, we recommend pulling the cable from the underside instead, taking care to place cable rollers to help support your installation and to prevent damage to your cable sheath. Setup for duct close to the floor Setup for pulling around bends Use sheave assemblies that exceed the minimum bending radius for pulling around bends. Pulleys must be positioned to ensure the effective curvature is smooth rather than polygonal. Maximum Pulling Tension When installing larger cables, it is advised to use a cable-pulling grip attached to the leading end of the cable’s metallic conductor. Where pulling attachments are used on the cables, they should be covered with protective tape to prevent the scoring of the cable trays, cable ladders, and installation pulleys. Based on the manufacturer’s recommendation, use a dynamometer to ensure that the cable’s maximum pulling tension is not exceeded. Table 1: Permissible Maximum Pulling Tension (Kgf) *Tip: The cable should be pulled at a constant speed. Drums with an extended length of cable should not be allowed to rotate too rapidly as the overrun can cause cable kinks and damage if the pulling is suddenly slowed or stopped. Side Wall Pressure Sidewall pressure is the tension that the cable experiences as it is pulled through a curved section. This is determined by both the pulling tension exerted on the cable as well as the bending radius limitation of the cable. To prevent damage, it is important to keep the side wall pressure below the 500 Kgf/m maximum permissible side wall pressure.

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How to Prevent Pest Attacks on Cables

Electrical cables are installed in almost all types of environments, and some are in areas more conducive to exposure to pests, rodents or termites. This is especially so for cables that are buried direct or for underground use cables. Cable materials are attractive to rodents due to plasticizers and aromatic odours. The colour and texture of the cable sheath material are also attractive to them. Termites live in underground nests deep in the soil. While their basic diet is cellulose, such as organic wastes and roots of plants, once they have consumed natural sources of cellulose, they would look for other manmade sources, such as cables.  When the cable insulation layer is chewed through, this can cause short circuits and potentially start an electrical fire. Therefore, where there is a risk of pests, rodents or termites, we would need to consider protective barriers or additives to be added to the cables to prevent damage. How can we protect cables from rodents, pests and termites?  There are two general methods to protect cables from rodents, pests and termites: physical barriers and chemical additives. Physical barriers For rodent and pest issues, physical barriers that help protect against them include using conduits and armouring tapes. These barriers prevent pests and rodents from gnawing on the cables. Using fibre-glass yarns is popular for optical fibre cables, but it becomes broken when bitten and unpleasant for rodents. For termites, an effective long-term physical barrier would be Nylon-12, which is a rigid material that termites are unable to bite through. In general, these physical methods may last longer but also tend to be costly. Chemical additives An effective alternative is the use of chemical additives labelled pest resistance (PR), anti-rodent (AR), and anti-termite (AT). Additives are added to the outer sheath of the cable when extruded to provide long-lasting effectiveness due to the controlled release of the active ingredients. Examples of anti-rodent ingredients include capsaicin (think chilli!), which is added and causes the sheath to have a spicy or bitter taste, discouraging animals from gnawing on the cables. Since the olfactory sense of animals is superior to humans, the additives give off an unattractive scent to animals but are non-toxic and not detectable to humans.  On the other hand, anti-termite cables are treated with insect growth regulators, which serve to repel and disrupt their growth and reproduction rather than exterminate them. If you know your cables will be installed in an environment where there could be potential pest attacks, check in with your cable manufacturer on the physical or chemical additives that would suit your needs.   At Keystone, regarding AR, PR, and AT chemical additives, our approach has been to use: 1) non-toxic products that are not harmful to humans or animals and 2) environmentally safe products. For more information on preventing pest attacks on your cables, please contact us. Contact Sales

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Key Principles for Cable Drum Handling and Storage

Cable drums are primarily meant to protect the cables from damage and to store cables properly for use. We have summarized some recommendations below for drum handling and storage as we employ these same methods in our factory and warehouse. It is important that cable drums are handled and stored correctly to prevent any unwanted impact or damage to the cables. Damaging cable drums due to mishandling could void your warranty with manufacturers if the cables were compromised. So it is important to take precautions. Handling Drums 1)Never attempt to move a cable drum by dropping the drum, such as from the transport vehicle. This will potentially damage both the drum and cable. Always use proper lifting equipment, such as cranes or forklifts, when moving drums. Storage of Drums 1)Drums should be stored on a hard surface with wedges or barriers to prevent the drums from rolling. 2)If the storage surface is soft or not flat, e.g. soil, it is important to elevate the drum off the ground to prevent the possibility of subjecting the drums to continually damp conditions that could damage the cable or the drum. 3)Avoid storing cable drums lying flat on the side, as this creates unwanted stress on the cable layers at the bottom. Drums should be stored upright. Uncoiling of Cables 1)To uncoil cables, support the drum on a jack stand or the equivalent. When using a stand, always be mindful of pulling the cable from the top, not the bottom, where the cable can scrape against the floor. 2)As aforementioned, avoid laying drums flat on the side. By the same token, avoid uncoiling cables from drums that are laid flat, as this could cause unwanted scratches to the cables against the drum flanges during the uncoiling process. 3)If a cable length has been cut from the drum, the exposed cable end remaining on the drum should be resealed immediately with a heat-shrinkable end cap to prevent any moisture or water ingress. The drum’s protective covering should also be restored where possible. We hope these simple principles help with your drum handling and storage. Feel free to access a more expanded visual guide by clicking the button below. DOWNLOAD GUIDE For more enquiries, please reach out to our team here. Contact Sales

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