Wire & Cable Application FAQ
Q. Why do all connection and control cables feature two rated voltage ranges, for example U0/U 300/500 V?
A: The rated voltage of a cable is the voltage on which the construction and testing of the cable is based in the context of electrical inspections. It is specified in the form of two voltage values: U0/U.
Many ÖLFLEX® connection and control cables have a rated voltage of U0/U 300/500 V.
-U0 is the rms-value (root mean square) of the voltage between a live conductor (core) and the earth (ground).
The earth can be a metallic cable sheath (copper braid) or an earthed surrounding medium such as the metal casing of a device or control cabinet.
The U0 value is lower than the U value, as there is as electrical separation only one layer of insulation between the live copper conductor and surrounding metallic medium.
-U is the rms-value of the voltage between 2 live conductors (cores) of a multi cored cable or within a system of single cores.
The U value is higher than the U0 value since there are always as electrical separation two layers of insulation between two live copper conductors in a multi-core cable or between two single cores in a switch cabinet.
The electrical voltage is measured in Volt (V).
Q. What is the difference between a copper braid screening and an aluminium laminated foil screening?
A: Virtually all ÖLFLEX® connection and control cables are screened with tin-plated copper braiding. UNITRONIC® data cables are screened with copper braids and aluminium-laminated synthetic foils, which are generally wrapped around the core bundle in overlapping spirals. Some data cables, such as the UNITRONIC® Li2YCY PiMF or ETHERLINE® Cat.5, actually feature both an aluminium foil and an additional copper braid. Copper braids primarily protect the cable against inductive coupling in the low frequency range in which virtually all connecting and control cables operate.
If, for example, a UNITRONIC® data cable is installed in the direct vicinity of an ÖLFLEX® connecting cable that may not have copper screen braiding, the data cable should be protected against inductive interference from the connection cable by means of a screening braid. The same applies if a connecting cable is installed in the proximity of an insufficiently shielded or EMC-compliant machine or in the vicinity of an electric motor, which can also generate fields of inductive interference. Aluminium foils are primarily used in data cables, as data is generally transferred at very high frequencies, thus necessitating protection against capacitive coupling. The so-called coupling resistance and the transfer impedance act as indicators of the shielding performance – the lower the measured transfer impedance, the greater the effectiveness of the cable screening. Of course, the best results are achieved by combining a foil shield with copper screen braiding.
The disadvantage is that the aluminium foil laminate makes the cable quite stiff and inflexible, meaning that it is mostly only really suitable for fixed installations in conventional cable construction design. Frequent movement of the cable can quickly tear or displace the sensitive foil shield, which will have a negative impact on screening performance.
Q. How do you define the specification "Minimum bending radius: occasional flexing" in the technical data in our catalogue?
A: The bending radii of cables are defined according to their installation type. In the case of fixed or static installation, a smaller bending radius can be chosen than would be required for flexible applications since the cable is only bent once in the former case.
In the cable industry, we generally distinguish between three installation types:
- Fixed installation: The cables are installed statically, in cable ducts for instance, where they are fixed and immovable. In this case, there should be no movement or vibrations during operation. The cables can therefore be bent more sharply and usually subjected to somewhat higher or lower ambient temperatures than in the case of flexible applications.
- Highly flexible application (e.g. permanent bending in drag chain): The bending radii specified for ÖLFLEX® and UNITRONIC® FD cables are always based on continuous flexible use in the energy supply chain. Even though all drag chains vary and have different parameters, it is possible to use the relevant bending radius, acceleration and travel to make an educated assessment as to a cable's suitability for the intended application. These specifications provide a relatively clear impression of the exact application planned by the customer.
- Flexible application (occasional flexing): Unfortunately, no exact definitions exist for this installation type, unlike for the fixed and highly flexible options. How often and how sharply a cable is bent in the customer's application varies from case to case. In order to reflect as many applications as possible, a relatively high bending radius is specified for this installation type. It is then largely irrelevant whether the cable is bent just once per day or moved more often, e.g. in the case of a connecting cable for a portable device that is unplugged/plugged in multiple times over the course of a day.
However, to avoid situations where cables that are not designed for highly flexible drag chain use are subjected to permanent bending outside the energy supply chain, the property "occasional flexing" is used on many of our catalogue pages. This reduces the danger of cables being used in continuous flexible applications for which they are not intended.
Q. Why are cables with black outer jackets better suited to outdoor use than cables of different jacket colors?
A: In outdoor use, cables are subjected to higher levels of UV radiation than when used indoors. They are also exposed to ozone effects and other atmospheric influences. In principle, all plastics are susceptible to oxidation. However, different types of plastic possess varying degrees of UV stability. Light and oxygen cause premature ageing of plastics as a result of photo oxidation. The UV rays contained in sunlight penetrate the molecular chains of the cable jacket. This causes the chains to split and results in the formation of highly reactive radicals, which continue to attack the molecular structure of the plastic. The ultimate consequence of this process is that plastics age and brittle faster in outdoor use. PVC cables in particular are subject to increased wear as the added volatile plasticisers or softeners in the thermoplastic polymer vaporize more quickly. There are a number of ways of protecting plastics against the effects of UV radiation. The material can be shaded from the light or special UV absorbers can be added to filter out the UV rays. The simplest way of making a cable UV-resistant is to add carbon black to the polymer used for the outer jacket, thus coloring it black. This ensures full shading of the jacket material, which results in complete light absorption. The harmful UV rays are absorbed by the carbon particles in the outer jacket and transformed into far less damaging thermal energy. This also prevents the formation of free radicals as well as the occurrence of photo-oxidation. As mentioned above, the different materials possess very different degrees of UV resistance. Some jacket materials display a good level of resistance to ultraviolet rays without the need for black coloration. Most of these substances are not thermoplastic polymers, which often require the addition of plasticisers, but belong to the group of cross-linked elastomers or TPE types. Non-black-colored PUR cables, for example, may fade or whiten in outdoor use, but usually maintain their flexibility and mechanical stability. Silicone cables without black-colored jackets, like the ÖLFLEX® HEAT 180, also possess a good level of UV resistance. However, such cables are only suitable for temperate climates. If used in locations with persistently high levels of UV radiation (coastal areas, deserts, oceans, high mountains, Polar Regions and areas with very high UV radiation such as South Australia or New Zealand), these cables should also be encased in a black, carbonized outer jacket.
Q. How do you calculate the maximum tensile load or suspension length of a copper cable?
A: Up to a maximum of 1000 N, the operational tensile strain for all cables and wires is calculated as 15 N of tensile load for each mm² of cross-sectional copper area. It is irrelevant whether the cables or wires employed have a solid or flexible conductor, or whether they are intended for fixed or flexible use. During laying or installing of solid conductor core cables, such as NYY for fixed installations, a factor of 50 N/mm² can be used.
Example calculation of maximum tensile load for an ÖLFLEX® CLASSIC 100 5 G 10 mm² (stranded flexible conductor) in operation:
Total copper cross-section: 5 cores x 10 mm² = 50 mm²
Tensile load in Newton: 50 mm² x 15 N = 750 N
Tensile load in kilograms: 750 N : 10 = 75 kg
Calculation of the resulting max. vertical cable suspension length:
Cable weight, version 5 G 10 mm²: 792 kg = 1000 m
Cable length, version 5 G 10 mm²: 75 kg = ??? m
Max. suspension length: (75 x 1000) : 792 = 94.7 m
If a cable features a separate support element, the maximum tensile load specified on the relevant catalogue page applies. Support elements are also required if a lamp, device or control console is to be affixed to a free-hanging cable. In this case, it must be ensured that the combined weights of the cable and the lamp or device do not exceed the maximum recommended tensile strain!
The mechanical tensile strain or force is measured in Newton (N).
Q. Where can I get the conductor resistance? And how do we calculate conductor resistance temperature dependence?
A: The conductor resistance of our cables is specified according to VDE 0295, depending on the cross-section. Please check catalogue appendix T 11.
The temperature dependence is according to the following formula
The Temperature Coefficient of Copper (near room temperature) is +0.393 percent per degree C. This means if the temperature increases 1°C the resistance will increase 0.393%.
Resistance values for conductors at any temperature other than the standard temperature (usually specified at 20 Celsius) on the specific resistance table must be determined through yet another formula:
The "alpha" (α)=0.393
Q. What is the meaning of "fire load in kwh/m" ? Why we need to measure and mention this?
A: There´s a short description of that topic. This is also depending on county specific standards.
The fire loading of a building or compartment is a way of establishing the potential severity of a hypothetical future fire.
It is the heat output per unit floor area, often in kJ/m2, calculated from the calorific value of the materials present. Fire loading is used for evaluating industrial safety risks.
An empty room with cement floor and ceiling, cinderblock walls, and no flammable materials would have approximately zero fire loading; any fire entering such a room from elsewhere will find nothing to feed on. However, nearly anything that makes a room useful (such as furniture, electrical appliances, or computer equipment), or attractive (such as wood panelling, acoustic tile, carpeting, curtains, or wall decorations), will increase the fire loading. Some usages inherently carry high fire loading as a side effect (an art gallery and studio, for example, is likely to contain large amounts of canvas, paints, solvents, and wooden framing). Buildings under construction or renovation tend to carry high fire loads in the form of construction materials, solvents, and fuel for generators.
Usually the fire load only is needed for installation cables in buildings. but could be also interesting for rolling stock to ensure the safety for the passengers etc.
Please see table T27 in our catalogue for Fire load values of cables.
Q. Why can a cable not be loaded with the same current amperage when used in different ambient temperatures?
A: The current transfer raises the temperature of cables and wires on the basis of the current amperage or the selected conductor cross-section. If the current is too high, a cable installed in a room temperature of +20°C can easily reach a surface temperature of +80°C. If the ambient temperature were also to increase significantly, the maximum permissible conductor temperature of the cable would be greatly exceeded. This could result in damage to the core insulation material, the cable sheath and even the copper conductor, or cause the premature failure of these components.
Depending on the applicable standards, the various copper conductor cross-sections are all assigned maximum current ratings. The core insulation material plays little to no part here. What is important is how the cable is installed and whether it is a single core or multicore cable. In accordance with DIN VDE 0298, part 4, table 11 (see catalogue appendix table T12-1), the power rating values specified here apply to an ambient temperature of +30°C.
As per column B of table T12-1, the maximum continuous current that can be supplied to an ÖLFLEX® 450 P 3 G 1.5 cable for hand-held equipment at an ambient temperature of +30°C is 16 A per core (1.5 mm²).
If the ambient temperature rises to +50°C, for example, the so-called “correction resp. reduction factor" comes into play, the aim of which is to reduce the current load on the cable.
The reduction factor to be applied is derived from the prevailing ambient temperature and the maximum permissible conductor temperature of the cable. On the catalogue page for the ÖLFLEX® 450 P cable, the maximum permissible conductor temperature is specified as +70°C. Based on these two temperatures, the reduction factor 0.71 can be read from table T12-2 ("Correction factors") in the catalogue appendix; the maximum current rating is then multiplied by this factor.
If a customer wants to supply for his application a 16 A current to an ÖLFLEX® 450 P 3 G 1.5 mm² cable at an ambient temperature of +50°C, a conductor cross-section of 1.5 mm² will be insufficient!
ÖLFLEX® 450 P 3 G 1.5 mm²:
Max. load at +30°C as per table T12-1, column B: 16 A
Max. load at +50 ℃ as per table T12-2: 16 A x reduction factor 0.71 = 11.36 A
Result: To be able to conduct a 16 A current at an ambient temperature of +50°C, the conductor cross-section must be increased to a suitable size.
ÖLFLEX® 450 P 3 G 2.5 mm²:
Max. load at +30°C as per table T12-1, column B: 25 A
Max. load at +50 ℃ as per table T12-2: 25 A x reduction factor 0.71 = 17.75 A
Result: Increasing the conductor cross-section from 1.5 mm² to 2.5 mm² produces the required value of 16 A at an ambient temperature of +50°C.
Note that this calculation does not take account of other important factors for the correct determination of cable ampacity, e.g. the type of installation!
The amperage is measured in Ampere (A).
Q. Is it possible to load a cable or wire with a voltage class of 300/500 V with a higher voltage for a brief period, provided that the testing voltage value is not exceeded?
A: Heating systems, for example, require a relatively high voltage to ignite the pilot flame, but this is only needed once or twice a day and for a matter of milliseconds. Operators and users are often of the opinion that a cable with a rated voltage class of, for example, U0/U 300/500 V can be briefly supplied with a higher voltage, provided that it does not exceed the specified testing voltage. In such cases, it is very important to note that a cable with a rated voltage class of 300/500 V and a testing voltage of, for example, 4000 V must never be subjected a voltage exceeding the specified rated voltage – not even for a matter of milliseconds! Even if, for example, a voltage of 2500 V occurs just once per day for a single second, the relevant cable, and the core insulation thickness in particular, must be constructed and tested to ensure the appropriate rated voltage. In this particular case, a cable a with a rated voltage class of 1.8/3 kV must be used to safely handle the briefly occurring voltage of 2500 V. The testing voltage listed for a specific product on the catalogue page, particularly in the case of ÖLFLEX® connection and control cables, in no way indicates that the relevant cable can be subjected to higher voltages – no matter how briefly. The withstand or high voltage test is a required element of the final acceptance resp. inspection of each and every cable and only serves as a means of identifying any insulation faults after production.
Q. What are the advantages of Tinned Copper conductor V/s Bare Copper conductor?
A: Bare Copper Wires vs. Tinned Wires
Copper itself is a great metal choice when it comes to electrical engineering. Everything from your car to your house, even city lights finds its current running through a copper wire or cable. Copper has a great conductivity (second only to silver,) a durable tensile strength and is easy to machine into wire and other specialty wire and cables. For these reasons, copper finds itself being used to create many alloys that are used for electrical work or for machining such as brass, nickel, silver or bronze.
However, even with the fairly high resistance to corrosion that copper has, wet environments or other places with high humidity find things like bare copper wire corroding and losing performance. So items such as solar panels or marine motors can quickly find their bare copper wires sporting some damage. That's where tinned wire comes into play. Tin plating helps to make a sort of specialty wire & cable. Where many plated wires, such as gold or nickel plated wires can be more for cosmetic purposes such as in jewellery wire wrapping, tin is a much more practical choice.
Benefits of Tinned Wire
Tin is a useful plating for copper because it not only , it also helps the wire to last much longer than it would normally. In fact, a 12 gauge tin coated copper wire can last up to ten times longer than a similar helps to boost copper's properties
- As tin resists corrosion and doesn't oxidize the plating helps to protect the copper underneath.
- This wards off additional wear and tear that would detract years off the life of a bare copper cable.
- This is especially so in instances where the operating temperatures of the wire exceed 100 degrees Celsius.
- At higher temperatures, the corrosion resistance of copper declines, making a tin coating valuable for protecting the wire in this state.
- It is also highly desirable for any marine electronics, and tinned copper is infamous for its uses in marine technologies.
Tinned wires are also desirable for soldering as they make connections and soldering an easy task given tin is a primary component in solder.
Tin also helps to strengthen the copper wire underneath, making it more resilient to breakage or lost connections while also boosting coppers conductivity.
So while tinned copper wire is more expensive than bare copper wire, it is often considered to be a much more prudent expenditure in the long run. Given that simple tin plating can drastically increase the life of copper, as well as ensure its effectiveness in high humidity areas, it pays for itself with strong performance and a lot less maintenance.
Q. What are the advantages and disadvantages of Stranded and Solid conductors?
A: In choosing the right type of wire for a project, there are a number of important considerations. Based on the amperage load and application, the electrician needs to determine the appropriate gauge of wire to use, as well as the type of metal wire to use.
Beyond choosing between aluminium or copper, the wiring expert will understand the difference between stranded and solid wire and will choose the appropriate wire core to use for their chosen project. While solid wire consists of a single metal core, a stranded wire is composed of numerous thinner wires laid together into a cohesive bunch. Both types of wire are appropriate for commercial and residential installation, however each has particular advantages and disadvantages that lead to the choice of one over another for each particular application.
While both types of wire will transmit electricity effectively, each is better suited to specific applications in both residential and commercial uses. Solid wire is the wire of choice for outdoor or rugged-duty applications which may expose the wire to corrosive elements, adverse weather condition or frequent movement. Stranded wire, conversely, serves a better purpose in intricate usages, such as electronic devices and circuit boards, where the wire will be protected but may undergo bending or twisting in order to connect electronic components.
The advantage of solid wire is one of cost, simplicity and durability. Because it is merely a single, thick strand of wire, the wire is very resistant to damage and extremely simple to make. However, for applications which require a great deal of movement — such as robotics or vehicular applications — or will require the wire to be bent into complex shapes — such as electronics and circuit boards — solid wire is undesirable because it lacks the strength and malleability to endure reshaping and motion. On the other hand, stranded wire is well-suited to applications which will demand flexibility and reshaping. For preventing electronic interference, however, stranded wire holds a disadvantage because the air channels between strands magnify the skin effect caused by magnetic fields on the surface of the wire.
In choosing based on cost, initial cost needs to be weighed against long-term durability. While a solid wire initially costs significantly less to purchase than stranded wire, a stranded wire will last longer in environments where motion or frequent alterations to the wiring may occur. All of these factors need to be taken into account before making a decision about the type of wire to choose for an application.
Q. Which cables are resistant to sea water?
A: In principle, most materials used in the cable industry are resistant to salt or sea water. Even though some plastics absorb more or less water than others, it is largely irrelevant whether the cables are made of PVC, PUR, chloroprene rubber, PTFE or even silicone. However, caution is advised in the case of some halogen-free and highly flame-retardant cables made of special, highly filled polymers. The flame-retarding additives can be strongly hygroscopic and are thus easily saturated with water. Even if the cable sheath compound displays no negative effects when exposed to sea water, not every cable is suitable for maritime use. At high sea in particular, cables are subjected to high levels of UV radiation and must be sheathed accordingly. Another factor to be considered is whether the cable only makes occasional contact with sea water or is used underwater on a permanent basis. As the water depth increases, so does the pressure on the cable. This is referred to as the water column. The pressure for a 1 meter water column is 0.10 bar. Therefore, at a depth of 100 meters, the pressure is already 11 bar (100 m x 0.1 bar = 10 bar + 1 bar air pressure at sea level). At this pressure, cables with many air cavities in the core stranding can become compressed, or the water may gradually diffuse through the cable jacket and insulation and reach the conductor. In many cases, cables intended for such applications are chosen indiscriminately due to a distinct lack of alternatives which have been thoroughly tested and approved for underwater use. However, deep-sea applications definitely necessitate special cables, which are designed to cope with the conditions and water pressures prevalent at such depths. Within the Lapp Group, LAPP Muller in France is one company that has specialized in the development of cables for underwater use.
Q. Is it true that only cables with a blue outer sheath must be used in "intrinsically safe circuits"?
A: No, that is not strictly true. The relevant standard (VDE 0165) merely stipulates that cables in intrinsically safe circuits must be labelled accordingly so that they can be identified as part of such circuits. In cases where cables in intrinsically safe circuits are to be indicated by their color, the outer sheath must be light blue. Cables which do not have a blue sheath but are still used in intrinsically safe circuits must be identified by other means, to be agreed with the relevant testing engineer/certifier. This can be done, for example, using blue cable ducts or by affixing FLEXIMARK® marking products. In some cases, cables forming part of intrinsically safe circuits can also be installed such that they are spatially separated from other cables. An exception to these rules is when the intrinsically safe or all non-intrinsically safe cables and wires are armoured, metal-sheathed or screened, in which case no separate identification of intrinsically safe cables and wires is required. The decision as to how cables are installed or distinguished in intrinsically safe environments must be made by the user in conjunction with the relevant testing institute.
Q. Why LAPP doesn't calculate voltage drops?
A: LAPP doesn't calculate voltage drops because the formula contains many variables and would require many data.
We can only provide resistance value of the conductor to calculate the drop. Customer can calculate on the actual installation type and other circuit parameters.
Why LAPP doesn't calculate voltage drops? Again below also will vary based on installation type and other circuit parameters.
How do you compute voltage drop and cable size over distance?
You must know the amperes the cable is conducting and the resistance of the individual core sizes.
Knowing this, the formula for calculating the voltage drop is
VD =I(amps )* R (ohm / mtr)
Knowing this, the formula for calculating the voltage drop for 100 mtr length.
VD=I(amps )* R (ohm / mtr) * 100 mtr.
where, VD is the voltage drop
I is the current(circuit current or current rating of the conductor after power de-rating)
R is the total resistance for the cable (Refer Table Table T11 of standard catalogue) convert to Ohm / mtr
R = resistivity of copper * (length in meters / area in square meters)
==========================================================================LAPP doesn't calculate voltage drops. And the formulas containing many variables would require many data.
We can only provide resistance value of the conductor to calculate the drop. Customer can calculate on the actual installation type and other circuit parameters.
Why LAPP doesn't calculate voltage drops? Again below also will vary based on installation type and other circuit parameters. Examples:
-For DC system
VD = I*R*L where,
I= current in the conductor
R= dc resistance of the cable per unit length
L=Length of the cable
-For 1phase AC system
VD= Iph*(R*cos(theta) + X*sin(theta))*L
R= ac resistance of the cable per unit length
X= reactance of the cable per unit length
cos(theta)= power factor
L=Length of the cable
-For 3phase AC system
VD= sqrt 3*Iph*(R*cos(theta) + X*sin(theta))*L
R= ac resistance of the cable per unit length
X= reactance of the cable per unit length
cos(theta)= power factor
L=Length of the cable
Q. What Makes a Good Instrument Cable?
A: The key factors to look for when choosing instrument cable are good screening from noise and low capacitance.
Keeping noise to a minimum is achieved by shielding the conductor from electrical interference, usually with a braided copper, some form of conductive plastic jacket, or both. Different manufacturers have different methods but, typically, any good quality audio cable should be appropriately screened.
Capacitance refers to the cable’s ability to respond changes in voltage, and is measured in picofarads (pF) per metre or per foot; a figure of around 70 pF/m would be quite low for instrument cable. Lower capacitance translates into better frequency response. Also, since capacitance is measured per unit of length, a longer cable will have more capacitance than a shorter one, so it makes sense to use only as much cable as you really need.
Q. What is the difference between control and instrumentation cable?
A: The difference between control and instrumentation cable is mainly in use. Either can be solid or stranded.
Back in the "good old days" control cables (for motors) needed to have larger wire than instrumentation cables in order to handle the larger currents required for the motor starters. They were typically terminated under screw terminals, and solid wire makes this termination easier.
The instrumentation cables were smaller diameter and frequently made of stranded wire which is more flexible. Today, with greater use of electronic starter controls, it is mainly switch gear (breaker) control wiring that needs the larger diameter wire.
The other difference between the 2 types is that the instrumentation cable is typically a shielded (screened), twisted pair. This construction serves to minimize "cross-talk" (inductive coupling) that causes erroneous readings for the instrumentation.
Thecontrol cables, whose circuits operated at 125 VDC, 110 VAC or 220 VAC levels were generally immune to this, and so did not require the shielding. When the control signals are run at 24 VDC, the shielded twisted pair construction is advised.
Still need to be careful about level separation, but as long as you are dealing with low DC voltages (28 V maximum), resistive loads, and using shielded twisted pair cables, can combine the control and instrumentation cores into a single cable where needed. (It is still better practice to keep them separate.) Also should keep inductive loads (like solenoids and relays) separate from the instrumentation, since they can create high inductive spike voltages when they are de-energized.
Important, you still need to choose a wire size sufficient to handle the maximum current and insulated for the maximum voltage. For the control wiring, be careful about using a single common wire for multiple devices - it will need to be sized for the total current.
Q. Where is the Instrument Cable used?
A: Today’s manufacturing and processing operations are largely controlled and measured by electronic circuitry. To ensure accuracy and greater control, interconnecting cables, Instrumentation cables are designed and manufactured to ensure ease of installation, minimum interference in transmission of signals and full compliance recognised industrial standards.
Instrumentation cables have very diverse applications. Manufactured to BS 53288 Cables are designed for use in communication and instrumentation applications in and around process industries like oil exploration, cement, paper, steel, power generation and others. Cables made to specific rigid requirements are utilised in process controls, transmission of signals, computers, control systems and monitor networks as well as power plants.
Instrumentation Cable is for use on Class 1 remote-control and signalling circuits where signals precision and accuracy is desired. These cables monitor process parameters such as pressure, flow speed, temperature and transmit low Voltage signals to the instrumentation and process control room. Instrumentation cables come in multiple twisted pair configurations with each pair gathering one set of process data.
For use indoors, outdoors, direct burial, free air, raceways, encased in concrete, open trays, troughs or continuous rigid cable supports.
For use in Class I, Div 2, hazardous locations.
For use as a non-power limited fire alarm circuit cable. Rated for wet and dry applications at temperatures not to exceed 90°C. Provides sunlight, cold bend and cold impact resistance.
Q. Why cables are in Twisted pair design?
A: Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of cancelling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighbouring pairs.