As you are working in automation, the type of cable used to carry the load is critical for the smooth operation of moving robotic or automated equipment. However, a cable isn’t going to do its job well enough to withstand constant abrasions and rotate only if it is flexible. Here, the constant motion of machinery can quickly degrade cables, leading to frequent failures and expensive downtime. Hence, you might need to look into a proper wire rated for such applications. According to most manufacturers, the cables suitable for such applications are “flexible cables.”
Table of Contents
- What are Flexible Cables?
- Bending:
- Torsion:
- Winding and Unwinding:
- Construction of Flexible Cables
- Stranding in layers
- Stranding in bundles
- Use within cable carriers/drag chains.
- Requirements For flexible Cables
- What is the difference between flexible cable and flexible cord?
- Several types of multi-conductor flexible cords are available:
- Conclusion
What are Flexible Cables?
Flexible cables are made up of hundreds of conductor strands or fine wires that you can bend millions of times. Moreover, it can retain its properties without breaking or losing the data transmission capacity or current movement.
Generally speaking, the motion of flexible cables can be either of three ways.
Bending:
You might bend the cable hundreds of times
Torsion:
In some cases, you might twist the cables longitudinally. Due to such torsional movements in wind turbines, this situation occurs. However, these cases are rare since twisting also comes with bending.
Winding and Unwinding:
The instance, when you unwind the cables from big reels. For example, in stage performance, where you will wind it for the time being and then store them for later use.
Aside from the braided conductor class, another feature that distinguishes a flexible cable from a less flexible one is the stranding. To grasp this, consider that thicker areas alternated with thinner areas as you braid closer together in a hair braid. Twisting the hair makes it thicker. In “stranding,” copper strands do something similar.
Manufacturers twist the thin metal wires to improve flexibility – if all strands and cores become parallel, it will extend the external copper cabling and compress the inner ones when the cable bent. It would stiffen the cable. The length of the lay controls thickness and versatility. The cable is thinner if it is longer and has less twist.
Cables that move a lot have sliding support that helps the components move as smoothly as possible. They also keep the cable round. For cables going through glands or connectors, leaks occur if you do not work properly around the sheath. Moreover, sliding supports can be fine plastic strands that slide between the cores. You will wrap it inpolytetrafluoroethylene filmfleece to make sliding easier, especially under torsion.
Caption: Optical Cable with hundreds of fibers
Construction of Flexible Cables
You can divide flexible cables into two types: conductors stranded in layers and bundled or braided conductors.
Stranding in layers
Because it is easier to make, stranding in layers is cheaper because it is easier to make. The cores wind strongly and leave several strands around the center. Then, a tube-shaped jacket of extruded plastic wraps them from the outside. For shielded cables, you will wrap fleece or foil around the cores.
However, when the cable core bends, the inner radius gets smaller, and the outer radius gets bigger as the wire core moves since the manufacturers have designed it that way. At first, this works well because the material is still flexible enough. But, the material can wear out and cause permanent changes. Thus the cores move and start to make their areas of compression and stretching, which can lead to a “cork-screw” form and, eventually, core breakdown.
Stranding in bundles
The second method of making flexible cable is by braiding the wires around a strainless center rather than layering them. This method makes sure that each conductor has the same radius for bending.
Every core quickly moves from the inside to the outer layer on the cable bending point. Because of this, no single core gets compressed inside or stretched near the front of the bend. It lowers stress overall. Moreover, it fills all the straps around the center and prevents them from coming apart. The result is a dynamic cable that is usually stiffer than a regular cable but lasts much longer in situations where it has to bend constantly.
Use within cable carriers/drag chains.
You can use flexible cables for various tasks because of their adaptability. However, you must cover them with cable carriers or drag chains to protect the flexible cables while building projects. It not only ensures the safety of workers but the well-being of cable as well.
So, if your cable is damaged, it will almost certainly be expensive to have it repaired. Additionally, the risk of injury increases if you leave the wires dangling in the air or running along the floor without an extra layer of protection. Hence, it is important to use the cable carriers over the flexible wires.
Caption: Black electrical cables with different flex capacity
Requirements For flexible Cables
Following are some requirements while installing the cables in flexible environmental conditions.
- You should use flexible cables in operating equipment that do not have rigid requirements.
- As per cable length, you need to cut the flexible cables so that they can respond to the short circuit situation. Also, it should be long enough to tolerate the risk of physical and mechanical damage.
- Multi-conductor flexible cables must be protected from permanent bending, abrasion, stress, and tight bends. Especially at the point of entrance in port connectors, minimal stress should be applied for better electrical performance.
- Additionally, you should avoid attaching the special cable to any equipment unless you have wrapped it in mechanical protection or rated it for permanent installation.
- You should not place flexible cables under carpet or floor covering since they can heat up and cause the insulation to burn. Moreover, the foot traffic can also damage the flex cables.
- Flexible cables should not be used under high temperatures. Additionally, these cables are also not suitable for freezing temperatures.
- Due to its characteristics, certain ratings will determine the short periods of continuous usage. However, flexible cables are not suitable for permanent installation outdoors.
Caption: Multiple thin insulated wires inside a protective cover
What is the difference between flexible cable and flexible cord?
Flexible Cable, Flex Cable, or Flexible Cord; you might mix these terms as companies use them interchangeably. However, they do have some differences in them.
As we talk about flexible cable, Flex Cable or flexing cable is a wire with hundreds of thin strands. Moreover, it is pliable and can tolerate a certain amount of flexing life cycles in its application time. However, another variation of flexible cables is called continuous-flex cables. Continous-flex works much better than simple cables in machinery used for control, data bus coaxial, fiber optic, power, and robotic applications.
On the other hand, Flexible Cords (also called Portable cords or service cords) connect the electrical devices to the power source. You can use them for temporary connections or permanent installation at your workplace. Moreover, they might have plugs available on one side to mate with the power plug and form strong connections in flex applications.
Several types of multi-conductor flexible cords are available:
- Type W Cable -8 AWG, 2000 VAC
- Type SOOW – 18 to 6 AWG, 600 VAC
- The Type SEOOW – 18 to 10 AWG, 600 VAC
- Type SJOOW – 18 to 10 AWG, 300 VAC
- Type SJEOOW -18 to 10 AWG, 300 VAC
And commonly used designations for flexible cable power cords include:
- SJ = Junior Severe Service (300-volt cords)
- S = Severe Service (600-volt cords)
- OO = Oil-Resistant Interior Insulation and Oil-Resistant Outer Jacket
- E = Thermoplastic Elastomer
- W = Weather and Water-resistant
Caption: Bundles of network cables
Conclusion
Flexible cables can tolerate twisting and turning. Moreover, they can be made with several methods, each with specific ratings and usage. However, as you apply them in a real environment, you have to check for the ratings to which it can comply. Also, you should not install them in places where the surrounding causes permanent damage to the cable. Here at Cloom, we offer wiring harnesses and cable assemblies with attention to detail. To avail of our services,contact us now.
FAQs
What are the OSHA guidelines for flexible cords? ›
The OSHA construction standard requires flexible cords to be rated for hard or extra-hard usage. These ratings are derived from the National Electrical Code, and are required to be indelibly marked approximately every foot along the length of the cord.
What are flexible cables used for? ›Flexible cables, or 'continuous-flex' cables, are electrical cables specially designed to cope with the tight bending radii and physical stress associated with moving applications, such as inside cable carriers.
What is the NEC code for flexible cords and cables? ›In the 2014 NEC, Section 400.7(11) allows a flexible cord to be run between an existing receptacle outlet and an inlet, where the inlet provides power to an additional single receptacle outlet. The wiring interconnecting the inlet to the single receptacle outlet must be a Chapter 3 wiring method.
What is the advantage of using a flexible control cable? ›Reliable control signal wiring is critical in today's demanding industrial and automated manufacturing environments.
What is the OSHA standard for safety cable? ›Cable shall be not less than 3/8 inch mild plow steel. Chain shall be not less than 1/4 inch alloy steel. The chain or cable shall be anchored at intervals not to exceed 100 feet. These anchors shall be of sufficient strength to support the imposed loads without deflection.
Which one of these guidelines for the use of flexible cords is true OSHA quizlet? ›Which one of these guidelines for the use of flexible cords is TRUE? They may not be attached to building surfaces. There is equipment with which falling materials could create a hazard.
When can flexible cords be used in the workplace? ›Use flexible cords and cables only for:
Splices in hard-service cord and junior hard-service cord (No. 14 and larger) can be repaired, but the splice must retain the insulation, outer sheath properties, and use characteristics of the cord.
How many types of Flexible Cable are there? There are four common types of cable flexing movements. These include rolling flex, bending flex or "tic-toc," torsional flex, and variable/random motion flex. These cables are meant for repetitive motions.
What are the essential features of a flexible cable? ›They have a high thermal rating and can withstand extremely high temperatures. RVV wires are available in different temperature modes such as 70°C, 90°C, 100°C, 150°C, 200°C, and 250°C. In the event of a fire, the impact is minimal.
What uses are not permitted for flexible cords? ›(2) Flexible cords, flexible cables, cord sets (extension cords), and power-supply cords are not permitted to be run through holes in walls, structural ceilings, suspended or dropped ceilings, or floors (Fig. 1).
Where can flexible cords not be used? ›
In other words, flexible cords when used in temporary wiring may be run through doorways, windows, or similar openings provided they are protected from damage, but cannot be used as a substitute for the fixed wiring of a structure; run through holes in walls, ceilings, or floors; attached to building surfaces; or ...
What is the voltage rating of flexible cable? ›Flexible three and four core heavy duty cables for working voltage 1100 volts. OHM/KM.
How is flexible cable different? ›Flexible cables are more flexible than ordinary cables. The conductor diameter of flexible cables is very small. However, in order to protect the conductor, the insulation material with a certain hardness and flexibility to resist machine fatigue and a certain strength is selected.
What is the most flexible power cable? ›Cicoil Flexx-Sil™ flat cables only use High-Flex, finely stranded wires, which are the most flexible wires available. The combination of our high-flex wire and the ultimate flexibility of our patented Flexx-Sil insulation make Cicoil flat cables the most flexible flat cable you can buy.
What is flexible control cable? ›Flexible multi-conductor control cables are for use with control on machinery, conveyors, control panels, assembly and production lines, and equipment building and processing equipment. SAB Flexing Oil Resistant Control Cables are designed to minimize downtime and save money by providing a long service.
What does the OSHA standard require flexible cords to be rated for quizlet? ›The OSHA standard requires flexible cords to be rated for: Hard or extra-hard usage. What is the most frequent violation of OSHA electrical standards? Improper grounding of circuitry and equipment.
What are the safety cable rules? ›The cable must be at least ¼” in diameter. Flagging must be present at a minimum of 6' intervals with high-visibility material. Must have a smooth surface so an employee does not sustain a puncture, laceration, or possibly snag their clothing. The system is properly spliced or terminated at walls, columns and posts.
What do all electrical cords need to have in order to work and be safe? ›All extension cords used on projects must be three-pronged and carry one of the designations required by the Occupational Safety and Health Administration (OSHA) and the National Electric Code (NEC). Each extension cord, power tool and receptacle, as defined earlier, shall be tested for grounding continuity.
What are the safety precautions in using extension and flexible cords? ›Do match up the plug and extension cord on a polarized cord (one hole on the plug is larger than the other). Do keep extension cords away from water. Do use GFCI (ground fault circuit interrupter) protection when using extension cords in wet or damp environments. Do keep extension cords away from children and animals.
Can flexible cords be used for OSHA quizlet? ›It is not a violation of OSHA requirements to use an extension cord without a grounding plug. If too many devices are plugged into the same circuit, a fire may occur. It is permissible to use a flexible cord as a substitute for fixed wiring.
Where flexible cord is approved for and used with a specific appliance it shall be considered to be protected? ›
Where flexible cord or tinsel cord is approved for and used with a specific listed appliance or luminaire, it shall be considered to be protected when applied within the appliance or luminaire listing requirements. For the purposes of this section, a luminaire may be either portable or permanent.
What should workers do before using a flexible cord? ›Portable cord- and plug-connected equipment and flexible cord sets (extension cords) shall be visually inspected before use on any shift for external defects (such as loose parts, deformed and missing pins, or damage to outer jacket or insulation) and for evidence of possible internal damage (such as pinched or crushed ...
Where flexible cords are permitted to be permanently connected? ›Flexible cords and cables shall be permitted for the electrical connection of permanently installed equipment racks to the premises wiring system to facilitate access to equipment or for the purpose of isolating the technical power system of the rack from the premises ground.
What are 4 safety precautions to take when using extension cords? ›- Don't overload and overuse extension cords. ...
- Choose the right extension cord. ...
- Don't connect multiple extension cords. ...
- Don't force a plug into the wrong kind of outlet. ...
- Avoid tripping or fire hazards.
There are three main types of data cables: Coaxial cable, Fiber Optic cable, and Twisted Pair.
What is 3 core flexible cable? ›A very popular choice for various uses is the 3 core cable. These are cables that include three separate conductors, for three different purposes of transporting electrical power. For instance, if you choose to use a 1.5mm 3 core flex cable, it will have three individual wires inside the main cable sheathe.
What are the three main types of cable? ›Twisted pair, coaxial cables and fiber optic cable are three major network cable types in the communication systems.
What are the advantages of flexible devices? ›Among the benefits of flexible electronics (compared to traditional, rigid alternatives) are size, weight, portability, and energy efficiency. Above all, they make previously impossible designs and technologies (such as wearable devices) possible.
What is the difference between flexible cable and flexible cord? ›Difference between flexible cable and cord
Flexing cord is designed for a specific number of flex life cycles over an application's runtime. Flexible cable is any cable that is flexible and easy to bend.
Flexible cords shall be used only in continuous lengths without splice or tap. Hard service flexible cords No. 12 or larger may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced.
What is the maximum length flexible cord that can be used to connect an electrically operated kitchen waste disposal? ›
(1) The flexible cord is at least 18 in. in length and no longer than 3 ft. (2) The receptacle is located to protect the flexible cord from damage. (3) The receptacle is accessible.
Can flexible cable be used for fixed wiring? ›An obvious use for flexible cables in fixed installations is for the final connection to equipment which may need to be adjusted, such as floodlights or motors. Flexible cables may also be used for overhead wiring between buildings.
What should you not use extension cords for? ›Using extension cords
Never use indoor extension cords outdoors. Don't plug multiple cords together. Don't run extension cords under rugs or furniture. Never tape extension cords to floors or attach them to surfaces with staples or nails.
The size stated for flex is given in mm2 and this measurement is actually the cross sectional area of the wire inside. The larger that area the higher the current it can carry. If a flex is used which is too small for the amount of current passing through, it becomes dangerous.
How thick is flexible cable? ›FFC cables are available in many pitches, such as 0.500 mm, 0.625 mm, 0.635 mm, 0.800 mm, 1.00 mm, 1.25 mm, 1.27 mm, 2.00 mm, 2.54 mm, but the most common pitches are 0.500 mm, 1.00 mm, and 1.25 mm.
What class of cable is flexibility? ›Class 1: Solid conductors, Class 2: Stranded conductors, Class 5: Flexible conductors, Class 6: Conductors with flexibility more than Class 5.
Are flex cables fragile? ›Flex circuits are more fragile. They can be easily dented, bent and damaged from minor impact or improper handling.
What is high flex cable? ›What is High Flex Cable? High flexible cables are built for extreme flexing and rigorous performance conditions. High flex cable and wire can withstand continuous flexing up to and exceeding a 10 million flex cycles. Galaxy can design a continuous flex cable to meet the most critical performance standards.
Why do we use flexible wires? ›Flexible cables, or 'continuous-flex' cables, are electrical cables specially designed to cope with the tight bending radii and physical stress associated with moving applications, such as inside cable carriers.
What type of cable is strongest? ›But the strongest cable material is again decided by the engineer's application requirements. Empirically, tungsten is the stronger material as compared with stainless steel alternatives. Pound for pound, tungsten, on the periodic table known as wolfram or simply W, is the strongest metal on earth.
What is the maximum length of flexible cord? ›
The length of the cord shall not be less than 450 mm (18 in.) and not over 900 mm (36 in.).
Where are flexible cords permitted to be used? ›Use flexible cords and cables only for:
Splices in hard-service cord and junior hard-service cord (No. 14 and larger) can be repaired, but the splice must retain the insulation, outer sheath properties, and use characteristics of the cord.
Connection of portable lamps or appliances; Elevator cables; Wiring of cranes and hoists (where flexibility is necessary); Connection of stationary equipment to facilitate their frequent interchange (equipment which is not normally moved from place to place, but might be on occasion);
What is the maximum length permitted for flexible cord used to supply an electrically operated in sink kitchen waste disposer? ›A flexible cord is permitted for an in‑sink waste disposal if: (1) The flexible cord is at least 18 in. in length and no longer than 3 ft. (2) The receptacle is located to protect the flexible cord from damage.
What are the safety rules with extension cords? ›- Never remove an extension cord's grounding pin to fit into a two-prong outlet.
- Avoid powering multiple appliances with one cord.
- Never use indoor extension cords outdoors.
- Don't plug multiple cords together.
- Don't run extension cords under rugs or furniture.
A receptacle outlet shall be installed wherever flexible cords with attachment plugs are used. Where flexible cords are permitted to be permanently connected, receptacles may be omitted.
What is the maximum length of a flexible cord if used to connect a built in dishwasher? ›For a built-in dishwasher, the length of the cord shall be 0.9 m to 2.0 m (3 ft to 6.5 ft) measured from the face of the attachment plug to the plane of the rear of the appliance. Receptacles shall be located to protect against physical damage to the flexible cord.