Metals Used in Network Wiring

Transcription

1 Metals Used in Network Wiring Contents Introduction - Metals Used in Network Cable Wiring... 2 Category Cables, Cat5 Cable, Cat5e... 2 History of Metals in Use for Cable Wiring... 2 Using copper and the alternatives... 2 The Problem with Copper Wire... 2 What is the alternative to copper?... 2 Use of Aluminum in Wiring Applications... 2 Use of Bi Metals - Bimetallic Copper Clad Wire in Current Use... 3 Emergence of Copper Clad Aluminum... 3 Manufacturing Processes used in Cable Wiring... 3 Plating Vs. Cladding... 3 Grading of the Copper Alternative Cables: Not all cables are created equal... 3 Features and Benefits of Cable Metals... 4 Features of bimetallic:... 4 Versatility of Bimetallics configurations:... 4 Advantages of Copper Clad Wire?... 5 Skin Effect Gives Excellent Conductivity... 5 A lighter material... 5 Resistance... 5 Use and Safety of Alternative Metals in Cable Wiring... 5 Problems with CCA... 5 Alternative metals and corrosion factors... 6 Fire and Smoke Safety... 6 Future use of Bi Metals... 7 Future of Cable Alternatives and sustainability... 7 References... 7

2 2 Introduction - Metals Used in Network Cable Wiring There are many varieties of metals used for cabling such as pure copper, clad copper and aluminum wire. This article discusses the various metals and manufacturing processes used in Category Cable construction for low voltage applications as well as electrical wiring in use presently. Category Cables, Cat5 Cable, Cat5e Cat5 cable consists of four pair cables for carrying signals. Mostly, the cable is used in computers for transmitting networks such as Ethernet. However, other signals such as telephony and video can be carried using the cables. Normally, punch down blocks and modular connectors are adopted to connect the cables. Cat5 has been advanced by the emergence of Cat5e technology that supports Ethernet, Fast Ethernet and Gigabit Ethernet (10/1000). The e in Cat5e refers to completely backward compatibility. Cat5e and Cat5 cables are made out of a copper material within a sheath, generally PVC. There are various type of Category Cable, for example those for use and rated for ceilings, for walls, outdoor and indoor. Cat5 and Cat5e are no exception. History of Metals in Use for Cable Wiring Using copper and the alternatives While pure copper was the original metal used most commonly alternatives in the market today will both carry the signal and are safe to use. There are critics of the use of alternative cables who consider these to be of low quality, stimulating a poor performance. Testing of quality alternative metal cables show no signal degradation as described by critics. The performance and safety of alternative cables are in the manufacturing process. Different manufacturers use different formulas and varying quality. Some of the very inexpensive alternatives have wreaked havoc in the marketplace confusing buyers and even falling apart during use. This is not true of all alternative bimetallic cables. The Problem with Copper Wire Despite being the best material, copper is expensive. To have a sufficiently strong copper wire requires a thickness that far exceeds the thickness necessary for most applications, thus wasting precious metals and increasing the cost of the wire. Therefore, people prefer to use other alternatives to save money, preferably without compromising quality. What is the alternative to copper? The evolving science of bimetallic conductors provides all the strength in wire with necessary conductivity at a fraction of the cost. Bimetallics can do this because it uses an innovative process of metallurgically bonding a layer of copper to either a core of steel or a core of aluminum. The bonding is completed with heat and pressure so that the two metals are permanently fused. Use of Aluminum in Wiring Applications The use of aluminum is nothing new; aluminum has been used for decades in electrical wiring and is still used today. Much has been said about the safety of this practice, but it is worth noting that most accidents involving the use of aluminum wire begin in the connections made and not in the substance itself. Also it should be noted that the high end CCA Cable is using a fusion of two metals, not a layer of material which inherently increases the rating of the metal.

3 Aluminum wire today is quite different than the past aluminum alloy as it is now rated 8000 series to exhibit a much greater terminal retention and strength than the old wires used. Aluminum is actually 200% more effective as a conductor than copper by weight, because of this; it is used more frequently in high voltage applications. Use of Bi Metals - Bimetallic Copper Clad Wire in Current Use It is currently being used many industries around the globe, such as: 3 Railways Telecom industry Electric industry Wind farms for grounding, servo magnet coil wire Automotive and heavy machinery - battery cables, signal wires, control cables Avionics - battery cables, signal wires, control cables Electronics as power wire, and internal fine wiring As building wire, copper clad aluminum wire is coming into markets around the globe. Bimetallics are slowly overcoming unfounded ideas about what this product is all about. As building wire, pure aluminum is unsafe without conversion to special connectors. Copper covered aluminum wire works well with copper wire. As its proven performance is gaining ground, the bimetallics world will see increased infiltration of the building world. Emergence of Copper Clad Aluminum The emergence of Copper Clad Aluminum (CCA) in the industry was one of the advancements that have seen growth in recent years. CCA wire uses aluminum bonded with copper. It was developed through a metallurgical process that bonds a thin layer of pure copper onto an aluminum core. The process minimizes manufacturing cost because aluminum has a lower cost than pure copper wire. This is one of the reasons why the technology has gained prominence. Copper Clad Aluminum is a growing market. Currently there are over 100 manufacturers of Copper Clad wire in China with revenues over $50 million. (Alibaba) These numbers indicate that the marketplace for CCA Cable is currently in the billions of dollars. Manufacturing Processes used in Cable Wiring Plating Vs. Cladding Bimetallic conductors are clad not plated. Although industry conducts both processes, it is important to note the distinctions and understand why cladding high-end CCA conductors are vital. Plating has some inherent problems. It is an electrochemical process where molten copper is applied to a core. The thickness is rarely uniform and there are often problems with porosity and gaps. Plated copper wire can fall prey to cracking and peeling. By contrast, cladding is mechanical. A solid sheet of copper is applied to the core. It is bonded so that it cannot be separated. The copper to core ratio is consistent and uniform, even at fine gauges. Grading of the Copper Alternative Cables: Not all cables are created equal Copper alternatives for cabling exist in different grades. Therefore, users should not dismiss its performance based on only the low-end knock-offs with inferior materials used in manufacture.

4 For instance, some manufacturers might build a CCA cable with only 5% copper (Sewell Development Corporation, 2015). Such minimization is unacceptable as it compromises the cables ability to provide typical Cat5e performance. A majority of applications for Cat5e standards advocate for a more than 25% copper content in the cable to ensure equitable performance as evidenced by more than 95% applications (HSMWIRE International, 2015). A good CCA Cat5e cable matches the performance standards of Cat5e easily. While the metal process is the same in the use of aluminum and copper, the amount of copper being used in manufacturing them, is different. A good manufacturer of copper clad aluminum cable will use a great deal more copper in the wire than those which are cheaply made of inferior products. This inconsistency in the industry causes a number of misconceptions about the qualities of the wire. In addition, due to the numerous ways in which this cable is made, consumers need to become aware of the different tricks likely to be used by retailers to confuse the buyer. The CCA cables often possess markings like Cat5e ANSI/TIA-568-C, ISO/IEC or BS EN that seek to fool the buyer into thinking the cables are compliant with the regulatory system or board. However, the different electrical properties of aluminum and copper compromise the standards of CCA over Cat5e. Therefore, the appropriate percentages as will be highlighted need to be considered to optimize performance. Features and Benefits of Cable Metals Features of bimetallic: Strands well, even at fine gauges. Very durable and resistant to fatigue. Flexible, light weight, and excellent for use as bunched wire. 2.7 times the length of copper at equivalent weight and one-third the weight at the same length. Does not require any special aluminum connector and can be safely interchanged with copper wire. Versatility of Bimetallics configurations: Two types: copper clad steel and copper clad aluminum. Supplied as wire, round or flat, strand or bunched fine-wire, tape, strip or busbar. All standard conductivity including 21%, 30%, 40%, 53%, and 70% depending on the content of copper are available. Offers a variety of steel grades, annealed or hard-drawn. Available in standardized copper to aluminum ratios by volume of 10% and 15% copper round wire and 20% copper flat wire with conductivities ranging from 63% to 67% IACS. It can be drawn to gauges as thin as 0.06 millimeters. 4

5 Advantages of Copper Clad Wire? Price After, the safety and efficacy of the product, this is primary. Copper wires cannot compete with the price of bimetallic copper clad wires. Copper prices are volatile. They fluctuate on the market based upon supply and demand. Heavy speculation on copper futures has created chaos in a product whose market was already unstable. Bimetallics is much more stable. Only between 3% to 10% of a bimetallic wire is copper and both core metals, steel and aluminum, are inexpensive by comparison. Performance Bimetallic copper clad wires outperform copper wires. Copper wires soft ductility with a low tensile strength make them prone to breakage. Bimetallic metal core solves this problem. As well, copper wire is not oxygen free. It may oxidize faster than bimetallic as these wires are usually made with oxygen free copper. Theft Target While copper is a target for thieves on the black market, bimetallics are resistant to theft. Copper is a highly sought after metal that is costly to replace and when a theft occurs, there is an interruption to service. With bimetallic, the risk is minimized. Copper clad steel is very strong and difficult to cut. Also, because the copper cannot be separated from the core metal, the thief cannot recycle or convert the wire. It has very low scrap value. Connectivity of Copper - Bimetallics have the connectivity and conductivity of copper. There is no special conversion of connectors nor special clamps or installation tools necessary. It is light weight and does not oxidize easily. Skin Effect Gives Excellent Conductivity The great thing about the alternative cables is the skin effect. The Skin Effect states that high frequency AC current density is greater near the outside (copper) surface of the wire than the center. The outside copper surface of bimetallics maximizes this conductivity. A lighter material Advantageously, CCA, as an alternative to copper use, is 63% lighter, which makes it easy to handle comparatively (Commscope, n.d.). Note that CCA presents excellent electrical performance and ease of handling. Hence, it is allowed under the NEC article 310, if listed and tested in accordance with UL 83, as a suitable replacement for solid copper in indoor power conduction and grounding applications. Resistance A closer analysis of the alternatives of copper, reveals that the resistivity of annealed copper is 1.72 x 10-8 whereas the resistivity of aluminum is 2.82 x The resistance of an aluminum conductors are therefore 64% above that of a copper conductors of equal cross-sectional area (Russ, 2012). The production of a composite CCA produces conductors that have resistance approximately 40% above the copper equivalent. In other words, CCA presents a 40% higher resistance, where copper has poor flexibility, can break easily, easily oxidizes causing poor terminations in the patch panel and module, and can easily be broken as aluminum is highly malleable compared to copper. Use and Safety of Alternative Metals in Cable Wiring Problems with CCA As noted by Cabling (2011), the Communications Cable and Connectivity Association (CCCA) along with the Copper Development Association (CDA), recently issued an alert regarding the emergence of a 5

6 counterfeit twisted-pair cable in the market. The twisted cable with CCA rather than solid-copper conductor is argued to be more likely to trigger damage in applications. Further, CCCA chair Kevin Ressler argued that contractors purchasing twisted-pair cable might not be sure that it is copper-clad aluminum and it does not meet the expected standards. Based on their statements, it remains critical to consider the percentage of copper in the CCA cable before purchasing. If the buyer is not sure or aware of the percentage of copper used in any given cable then consideration should be thoughtful to avoid compromising on the quality of performance. Significantly, one needs to weigh the advantage of buying pure copper, which costs double the price of the alternative cabling, as well as the manufacturing process used in alternative cables. Alternative metals and corrosion factors Critics of Copper Clad Aluminum cable argue that solid copper outlasts bimetallic cables and are not as effective as they ought to be. Both Copper and Aluminum corrode over a period of time. The process of cladding aluminum wire with copper extends the time frame by which any singular metal corrodes by protecting the inner metal with the manufacturing process applied by cladding. Testing has shown the corrosion rate of aluminum even in marine environments is over 20 years. (AluminumDesign.net). Additionally, in electrical applications copper clad aluminum solves many of the problems of termination as the side contacts of the cable contacts the copper side of the terminal virtually eliminating galvanic corrosion. (emsclad.com) Fire and Smoke Safety There has been some talk of the use of alternative cables pertaining to fire and safety risks. This is an unproven assumption on the very unrealistic end of the spectrum. The most prominent cause for concern in cabling is actually smoke inhalation from PVC jackets. This is also true of the materials used in pure copper manufacturing. Cited in many articles on the disadvantages of BiMettalic metals are the case of the MGM Grand Hotel Fire and the Swiss Air Fire, both of which were either aggravated or caused by wiring issues. However, these issues do not relate to inferior cabling, but moreover relate to the issue of smoke inhalation from PVC and in the case of Swiss Air related to the power supply copper wire that caused an arching event. A segment of in-flight entertainment network (IFEN) power supply unit cable (1-3791) exhibited a region of resolidified copper on one wire that was caused by an arcing event. (Aviation Investigation Report A98H0003) These types of events and articles are often cited incorrectly to prove a point about the use of copper wire in order to sell more copper wire exclusively. In addition some indicate that fire is a risk due to the lower burning point and the combustibility of aluminum and copper are only indicative if there is use of Power Over Ethernet, and even then the voltage that could result in fire is less than 40 watts through the wire. Aluminum melts at the temperature of 1200 degrees Fahrenheit and copper at 1900 degrees. Since the ignition point of wood is about 800 degrees. It should be noted the house will burn down before the aluminum in the wire does. (EngineeringToolbox) According to the U.S. Fire Administrator, most electrical fires are caused by faulty electrical outlets and old, outdated appliances, not by the wiring itself. Some of this can be attributed to oxidation of 6

7 terminals, expansion and contraction due to heating and cooling. That is primarily because aluminum expands and contracts at a different rate than copper, and switches and receptacles were designed for copper s rate of expansion and contraction. (U.S. Fire Administration/FEMA) Future use of Bi Metals The most exciting industry the bimetallic world is looking at is that of renewable energy. The wind, solar, and undersea umbilical sources are ripe for use of bimetallic wire. The other industry that looks to the future with bimetallics is Telecom. Data and LAN cables are an untapped future use. There are also ongoing and revolutionary possibilities for the consumer electronics, white goods, and automotive cable industries. Looking into the future, engineers of cable installations must gain the knowledge of the options available. The advantages and concerns of different metals and components must be assessed for each system. Cable manufacturers need to communicate with the large standards and certification agencies to legitimize and endorse bimetallics on a broad scale. The cable and bimetallics industries should partner to create innovative cables at a lower cost in a broad venue. Through use of bimetallics we could see a boom for everyone, customers, cable manufacturers, and bimetallics suppliers, alike. Future of Cable Alternatives and sustainability While emerging technologies are sometimes slow to gain acceptance, the use of high end CCA cable in most applications, other than stringent government operations, is widely known. In 2014 the UL labs put out a memo stating that they are ready to certify Copper Clad Aluminum connectors in limited power use. (UL Labs, 2015) It s only a matter of time before alternatives in cable markets also reach a point of certification and acceptance. While education in the industry is needed to help engineers and cable installers learn about the applications in which bimettalics can be used, acceptance has been ongoing over time. As many now know, bimetallics are cheaper, stronger, more flexible, lighter, and more secure than the copper alternative lending to the need for changing attitudes in the marketplace. Bimetallics manufacturers have begun to assist cable manufacturers with bimetallic clad wire conversion in a variety of ways including testing, quality assurance, certification, and academic research. Highlighting the current successful application of their use References (UL Labs, 2015) Cabling. (2011, March 4). CCCA, CDA warn against copper-clad aluminum cables. Retrieved from Commscope. (n.d.). Copper-Clad Aluminium (CCA) Indoor Wiring Solutions Guide HSMWIRE International. (2015). Copper Clad Aluminum Wire. Retrieved from 7

8 8 Russ. (2012, October 24). Whats wrong with cheap Cat5e cable? Retrieved from Sewell Development Corporation. (2015). Network Cable Central. Retrieved from Aviation Investigation Report A98H EngineeringToolbox: ( (U.S. Fire Administration/FEMA),