1. Introduction to Bare Conductors

A bare conductor, in the realm of electrical engineering, is fundamentally defined as a conductive material designed to carry electrical current that lacks any form of covering or electrical insulation. This absence of insulation is a defining characteristic that dictates its specific applications within electrical systems. The primary role of any conductor, bare or insulated, is the efficient and safe conveyance of electrical power. However, the uninsulated nature of bare conductors offers distinct advantages in certain scenarios, particularly in terms of heat dissipation. When electrical current flows through a conductor, it generates heat due to the inherent resistance of the material. Insulation around a conductor can impede the transfer of this heat to the surrounding environment, potentially leading to overheating, reduced efficiency, and even premature failure of the conductor or the insulation itself. Bare conductors, lacking this thermal barrier, allow for a more direct transfer of heat, making them suitable for applications involving high currents where efficient cooling is essential.  

The selection of materials for bare conductors is primarily driven by the need for high electrical conductivity. The most common materials employed are copper and aluminum. Copper is often the preferred choice due to its excellent electrical conductivity, which is second only to silver, and its inherent resistance to corrosion. Typically, bare copper conductors are composed of 99.99% pure copper to maximize conductivity and flexibility. These conductors can be manufactured in either solid or stranded forms. Solid bare copper wire consists of a single continuous piece of metal and is well-suited for applications where minimal bending or movement is expected. In contrast, stranded copper wire conductors are fabricated by intertwining multiple smaller wires, which enhances both the conductor's pliability and its ability to withstand fatigue, making them advantageous in contexts requiring frequent movement or alterations in shape. For specific applications, such as marine environments where corrosion is a significant concern, tinned copper conductors, which have a thin layer of tin applied to the surface, offer enhanced resistance to oxidation and corrosion.  

Aluminum stands as another prominent material for bare conductors, particularly favored for its lightweight nature and cost-effectiveness. While aluminum's electrical conductivity is lower than that of copper, its significantly lower density makes it a compelling option for expansive installations like overhead power transmission networks where the weight of the conductor can become a critical factor. To address the need for both conductivity and mechanical strength in such applications, specialized types of bare aluminum conductors have been developed. Aluminum Conductor Steel Reinforced (ACSR) is one such type, which combines the excellent conductivity and lightness of aluminum with the high tensile strength of a steel core. This composite construction allows for longer transmission line spans with reduced sag. Other variations include All Aluminum Conductor (AAC), which is primarily used in urban areas where its lightweight is particularly beneficial, and All Aluminum Alloy Conductor (AAAC), which offers improved corrosion resistance compared to AAC, making it suitable for specific environmental conditions. In some bare conductor designs, particularly those requiring significant mechanical strength, steel itself is utilized, often as the central core in conductors like ACSR, to provide the necessary rigidity and tensile strength for installation and operation. Additionally, zinc-coated steel wires (TK) find use in certain bare conductor applications where high mechanical strength is the primary requirement. The diverse range of materials and constructions available for bare conductors underscores the importance of tailoring the conductor's properties to the specific demands of its intended application.  

Bare electrical conductors are categorized based on their material composition, construction, and specific application requirements. Fundamentally, they can be classified into solid and stranded conductors. Solid conductors consist of a single strand of conductive material, offering simplicity and robustness for stationary applications. Stranded conductors, comprising multiple wires twisted or braided together, provide increased flexibility and resistance to fatigue, making them suitable for dynamic or vibration-prone environments. Beyond these basic forms, bare conductors also include flat strap conductors, commonly known as busbars, which are solid pieces of metal drawn into a flat, rectangular shape and are often used for power distribution within electrical equipment or substations. Braided conductors, constructed from multiple strands woven together, offer a high degree of flexibility and are utilized in applications like grounding straps or flexible connections. This variety in type and construction highlights the adaptability of bare conductors to meet the diverse and specific needs of electrical systems, ranging from simple grounding connections to the complex demands of high-voltage power transmission.  

2. Bare Conductors in Overhead Power Transmission Lines

Bare conductors play a pivotal role in the infrastructure of overhead power transmission lines, which are essential for delivering electricity from generating stations to substations and ultimately to end consumers. These lines form the very backbone of electrical grids, responsible for the transmission of high-voltage electricity over vast distances with minimal energy loss. Indeed, the overhead lines seen on high-voltage transmission towers are typically bare conductors.  

The use of bare conductors in these applications offers several key advantages. Foremost among these is cost-effectiveness; the absence of insulation significantly reduces the material and manufacturing expenses associated with these extensive networks. Furthermore, the lack of insulation allows for superior heat dissipation. High-voltage transmission inherently involves the flow of large currents, which generate substantial amounts of heat. The ability of bare conductors to readily dissipate this heat into the surrounding air is crucial for maintaining their operational efficiency and preventing overheating. Additionally, bare conductors are generally lighter than their insulated counterparts. This lighter weight is particularly advantageous for long-span transmission lines, as it reduces the overall load on the support structures and simplifies the installation process. The high conductivity of the materials used, primarily aluminum and copper, also ensures efficient power transfer over considerable distances, minimizing energy losses due to resistance. The fundamental reason for employing bare conductors in overhead transmission lines stems from a combination of economic practicality and technical necessity in managing the high voltages and currents involved. Insulating the immense lengths of conductors required for national and regional power grids would be prohibitively expensive. More critically, the thick insulation needed for high-voltage lines would add substantial weight, necessitating much stronger and more costly support structures. Moreover, the insulation would act as a barrier to heat dissipation, potentially leading to dangerous temperature increases within the conductors and increasing the risk of failure. By utilizing the surrounding air as the primary insulating medium, bare conductors overcome these challenges, providing an efficient and cost-effective solution for large-scale power transmission.  

The selection of the specific type and material of bare conductor for overhead transmission lines is a critical engineering decision that takes into account various factors, including conductivity requirements, mechanical strength needs, environmental conditions, and economic constraints. Aluminum has emerged as the preferred material for many high-voltage transmission projects due to its favorable balance of weight and cost for large-scale deployments. For very long spans or areas prone to high winds and ice loads, Aluminum Conductor Steel Reinforced (ACSR) is frequently employed. In this composite conductor, the central steel core provides the high tensile strength necessary to support the weight of the conductor over long distances, while the outer layers of aluminum strands ensure good electrical conductivity. This design effectively separates the mechanical support function from the electrical conduction function, allowing for optimized performance in both aspects. In urban areas, where the weight of the conductors can impact the design of support structures, All Aluminum Conductor (AAC) is often utilized due to its lighter weight. For environments with higher levels of pollution or humidity where corrosion might be a greater concern, All Aluminum Alloy Conductor (AAAC) offers improved resistance to degradation. While copper possesses superior electrical conductivity compared to aluminum, its greater weight and higher cost generally make it less practical for the vast distances involved in most overhead transmission lines. However, copper conductors may still be used in specific applications where its higher conductivity is deemed essential and the span lengths are shorter. The choice of conductor material and construction for overhead lines represents a careful optimization process, balancing the need for efficient and reliable power delivery with the practical considerations of installation, environmental resilience, and economic viability.  

The installation and operation of overhead bare conductor systems necessitate careful consideration of safety protocols. Maintaining adequate clearances between the conductors and the ground, as well as from nearby structures, is paramount to prevent accidental contact and ensure public safety. Over long spans, the phenomenon of conductor sag due to the weight of the conductor and environmental factors like temperature variations must be accounted for in the design and installation to maintain these clearances. In these high-voltage systems, the air surrounding the bare conductors acts as the primary electrical insulator. The insulating properties of air are generally excellent, but can be compromised under extreme conditions, such as very high humidity or the presence of contaminants. To further mitigate the risk of electrical faults, especially due to arcing between conductors, transmission towers are designed with sufficient spacing between the individual conductors carrying different phases of electricity. In some cases, spacers are also used along the length of the lines to maintain a safe distance. The design and construction of overhead bare conductor systems rely on a fundamental understanding of electrical principles, material properties, and environmental factors to ensure the safe and reliable transmission of electrical power over long distances.  

3. Application of Bare Conductors in Electrical Grounding Systems

Bare conductors are indispensable components in electrical grounding systems, which are critical for ensuring the safety of electrical installations and protecting equipment from damage. Grounding provides a low-resistance pathway for fault currents to flow safely to the earth, thereby minimizing the risk of electric shock to individuals and preventing overvoltage conditions that can harm electrical equipment. This process also plays a vital role in dissipating electrical surges, such as those caused by lightning strikes, safely into the ground. Furthermore, a properly designed grounding system contributes to the overall stability of electrical networks by providing a common reference point for voltage levels. The use of bare electrical wiring is of paramount importance in grounding and earthing systems, where it serves as a secure and low-resistance route for fault currents to be dissipated into the ground, significantly diminishing the potential for electrical dangers and bolstering the overall protection of the system.  

Bare copper conductors are extensively utilized as grounding wires and electrodes in a wide range of electrical installations due to their excellent electrical conductivity and inherent resistance to corrosion. They are commonly employed as earth electrodes, which are conductive elements buried in the earth to provide a direct electrical connection to the ground. These electrodes can take various forms, including rods driven into the ground, wires buried in the soil, or even metallic components embedded in concrete foundations. The absence of insulation on these grounding conductors is crucial for their effectiveness. Insulation would impede the flow of fault current from the conductor into the surrounding earth. By using bare conductors, a direct and low-resistance pathway is established, allowing for the rapid and efficient dissipation of any stray electrical currents. This direct contact with the earth is a fundamental principle of electrical grounding, ensuring that the potential difference between energized equipment and the ground remains within safe limits.  

The advantages of using bare conductors in grounding applications are numerous. Their inherently low electrical resistance is paramount, as it allows for the maximum flow of fault current to the ground, facilitating the rapid operation of overcurrent protective devices like circuit breakers and fuses. Furthermore, bare conductors, particularly copper, exhibit excellent durability and resistance to environmental degradation. Unlike insulated wires, bare copper is not susceptible to the deteriorating effects of soil, moisture, or various chemical agents commonly found in the ground. This robustness ensures the long-term reliability and effectiveness of the grounding system. From an economic standpoint, bare conductors are generally more cost-effective than insulated ones, as the absence of insulation reduces both material and manufacturing costs. This is a significant advantage, especially in large grounding systems that require extensive lengths of conductor. Bare wire also possesses a high current-carrying capacity, enabling it to handle substantial fault currents without melting or failing. In below-grade grounding systems, the use of bare conductors maximizes the "leakage current" capacity and expands the sphere of influence of the grounding system. This means that a larger volume of earth is effectively utilized for current dissipation, leading to a lower overall resistance to earth. The combination of performance benefits and cost savings makes bare conductors the preferred choice for the majority of electrical grounding applications.  

Electrical codes and standards, such as the National Electrical Code (NEC) in the United States, provide specific guidelines for the installation and use of grounding conductors. NEC Article 250 is dedicated to the requirements for grounding and bonding of electrical systems. According to these regulations, equipment grounding conductors (EGCs) are permitted to be bare, covered, or insulated. When insulated conductors are used for equipment grounding, those of size 6 AWG and smaller must have a continuous outer finish that is either green or green with one or more yellow stripes. For larger equipment grounding conductors, sized 4 AWG and larger, the insulation is not required to be green along its entire length, but it must be permanently identified as a grounding conductor with green markings at each end and at every point where the conductor is accessible. Grounding electrode conductors, which connect the system grounded conductor or the equipment to the grounding electrode, are sized based on the size of the largest ungrounded conductor supplying the system. The NEC mandates a minimum of two grounding electrodes unless a single electrode exhibits a resistance to earth of 25 ohms or less. Bonding, which involves connecting metal parts to establish electrical continuity and conductivity, is also a critical aspect of grounding systems. For below-grade grounding applications, bare copper is considered suitable and often preferred to maximize the contact area with the earth and facilitate efficient current dissipation. While bare copper is generally suitable for direct burial in grounding systems, local codes and specific soil conditions may influence installation practices. These code requirements reflect the importance of a properly installed and effective grounding system for ensuring electrical safety and equipment protection.  

4. Use of Bare Conductors in Substations and Switchyards

Substations and switchyards, being critical nodes in the power transmission and distribution network, extensively utilize bare conductors for various essential functions, including busbars, interconnections, and grounding systems.  

Within substations, bare conductors are commonly employed to create busbars, which serve as central distribution points for electrical power, allowing current to be efficiently routed between different pieces of equipment such as transformers, circuit breakers, and transmission lines. These busbars are typically constructed from rigid, high-conductivity materials like copper or aluminum, often in the form of flat bars or tubular shapes. Flat bars are advantageous for their ease of bending and joining, making them suitable for lower voltage applications and complex layouts. For high-current applications, multiple flat bars may be grouped together with a small space between them to aid in heat dissipation. However, the number of bars that can be effectively grouped is limited by skin and proximity effects, and flat bars are generally restricted to lower voltage levels due to the potential for corona discharge. Square and round tubular conductors offer greater rigidity compared to flat bars of the same ampacity, enabling longer spans between supports. The flat surfaces of square tubes provide convenient connection and support points, while round tubular conductors are particularly popular in outdoor substation construction due to their structural and electrical efficiency, as well as their ability to minimize corona discharge at higher voltages. Flexible stranded conductors, which are cables fabricated by stranding together multiple smaller conductors, are also utilized in substations for equipment taps and connections where some degree of flexibility is required. The choice of busbar conductor shape and material in a substation is a critical design consideration that depends on factors such as the operating voltage, the magnitude of current to be carried, and the structural requirements of the installation. High-voltage substations often favor tubular conductors to mitigate corona effects, while high-current applications may necessitate larger cross-sectional areas or parallel conductors to manage heat and electromagnetic effects.  

A robust grounding system is absolutely essential in substations to ensure the safety of personnel and the reliable operation of equipment, and bare copper conductors play a fundamental role in achieving this. Substation grounding grids are typically designed using a network of interconnected bare copper conductors, often ranging in size from 1/0 AWG to 4/0 AWG, buried in a grid pattern beneath the substation. This grid provides a low-impedance path to earth for any fault currents, ensuring that equipment enclosures and the ground surface remain at safe voltage levels, thereby protecting personnel from step and touch potentials during fault conditions. In accordance with the NEC, metallic fences and other metal structures located within a certain proximity (e.g., 16 feet) of exposed electrical conductors or equipment in a substation must be bonded to the grounding electrode system using wire-type bonding jumpers, which are often bare copper conductors. These bonding jumpers are required at fence corners, at regular intervals along the fence, and at any point where overhead conductors cross the fence. Gates must also be bonded to their support posts, and any openings in the fence must be bridged by buried bonding jumpers. The grounding grid itself should extend to cover the swing area of all gates. This comprehensive bonding and grounding approach minimizes the risk of dangerous voltage gradients developing on or around the substation perimeter.  

The selection of conductor materials for substations involves a trade-off between electrical performance, environmental considerations, and cost. Copper and aluminum are the primary choices. While copper offers higher electrical conductivity, aluminum is increasingly favored due to its lighter weight and lower cost, especially for large installations. However, for a given current-carrying capacity, an aluminum conductor will typically need to be larger than a copper conductor due to its lower conductivity. The ampacity of bare conductors in substations is influenced by several factors, including the conductor material, the proximity of adjacent conductors, prevailing climatic conditions (ambient temperature, wind), the permissible temperature rise of the conductor, its surface emissivity, and the altitude of the substation. Copper conductors can generally carry a higher current than aluminum conductors of the same size, but for the same ampacity, the weight of copper required is significantly greater. As substations are often located outdoors, the corrosion resistance of the conductor material is an important consideration. While both copper and aluminum exhibit good corrosion resistance, the specific environmental conditions of the substation location may influence the choice of material or the need for protective coatings or alloys. The design and material selection for conductors in substations and switchyards represent a careful balance of electrical, mechanical, environmental, and economic factors to ensure a safe, reliable, and efficient power delivery system.  

5. Bare Conductors in Specific Machinery and Equipment

While insulated wires are predominantly used for the internal wiring of most machinery and equipment to prevent short circuits and ensure safety, bare conductors find specific applications within certain types of electrical apparatus, particularly in grounding and specialized connections.  

In electric motors and generators, the windings that carry the main operating current are typically made of magnet wire, which has a very thin layer of insulation to prevent short circuits between the numerous turns. While these wires might appear bare at first glance due to the thinness of the insulation, they are indeed insulated to ensure proper operation. However, bare conductors, usually made of copper, are often used for grounding the frames and other non-current-carrying metallic parts of motors and generators to provide a path for fault currents in case of insulation failure. This grounding is crucial for safety, as it helps to prevent electrical shocks. Additionally, specialized cables designed for connecting portable power generators may utilize bare copper conductors within their construction. These cables often feature multiple conductors, some of which may be bare copper strands to provide flexibility and high current-carrying capacity, while the overall cable assembly is protected by an outer insulating jacket and sometimes additional inner layers for safety and durability. These applications highlight the role of bare conductors in ensuring the safe and efficient operation of rotating machinery, even if they are not the primary current-carrying elements within the active components.  

In industrial equipment and appliances, bare conductors can be found in specific scenarios. For instance, in some industrial wiring installations, particularly in controlled environments where the risk of accidental contact is low, bare copper conductors might be used for certain connections, with insulation being added separately as needed. They are also utilized for making high-current connections to large industrial equipment, ensuring stable and reliable power supply. Within electrical panels and inside some appliances, particularly older models or those designed for specific industrial uses, bare conductors might be used for internal wiring where the enclosure provides a degree of physical protection. Furthermore, bare copper conductors are commonly used for earthing or grounding electrical appliances and equipment, providing a direct path for any fault current to be safely discharged to the ground, thereby preventing electrical hazards and protecting the equipment from damage.  

The choice of using solid or stranded bare conductors in machinery and equipment depends on the specific requirements of the application. For connections that are not subject to movement or vibration, solid bare copper wire might be sufficient. However, in applications where flexibility is needed, such as in wiring harnesses or connections to moving parts, stranded bare copper conductors are preferred due to their ability to withstand bending and flexing without breaking. Regardless of whether solid or stranded, the high electrical conductivity of copper and aluminum is essential for ensuring efficient power transmission within the equipment. Proper sizing of the bare conductor is also crucial to ensure that it can safely carry the intended electrical load without overheating or causing excessive voltage drop. The specific mechanical and electrical demands of the machinery or equipment dictate the type, size, and material of the bare conductor used, reflecting the need for tailored solutions in different engineering applications.  

6. Other Applications of Bare Conductors

Beyond the primary applications in power transmission, grounding, substations, and machinery, bare conductors find use in a variety of other specialized electrical systems.

One significant area is in lightning protection systems, where bare copper or aluminum conductors are essential components. These systems are designed to provide a safe, low-resistance path for the immense current from a lightning strike to travel to the ground, thereby protecting buildings and other structures from damage. Bare conductors are used as down conductors, which connect the air terminals (lightning rods) on the roof to the grounding electrodes in the earth, as well as roof conductors that interconnect the air terminals. Bonding conductors, also typically bare, are used to equalize the electrical potential between different grounded metal bodies or conductive objects and the lightning protection system. The materials used for these conductors, such as copper, aluminum, copper alloys, and copper-clad steel, must be corrosion-resistant to ensure the long-term effectiveness of the system. Compatibility between different metals is also important to prevent galvanic corrosion. Interestingly, lightning conductors can be installed in direct contact with wood and other flammable materials because the extremely short duration of a lightning strike minimizes the time for significant heat to be generated in the conductor and ignite the surrounding materials. The fundamental principle behind using bare conductors in lightning protection is to provide a highly conductive, unimpeded path for the lightning's energy to be safely dissipated into the earth.  

In the realm of telecommunications, bare copper conductors serve several important functions. They are commonly used for grounding telecommunication networks and equipment, ensuring the safety and proper operation of sensitive electronic devices. Bare copper conductors are also employed in the construction of coaxial cables, where they often form the central conductor responsible for transmitting the signal, although in this case, they are typically insulated from the outer shield. Additionally, they are used in the wiring for traditional telephone lines and internet cables, providing a reliable medium for signal transmission. Due to the need for flexibility in many telecommunications wiring applications, stranded bare copper wire is often preferred.  

Beyond these major areas, bare copper wire finds use in various other specialized applications. Its excellent electrical conductivity makes it suitable for electrical hookups and as jumpers in temporary or testing circuits. The malleability and aesthetic appeal of bare copper also make it a popular material in arts and crafts, used for creating sculptures, jewelry, and other decorative items. In industrial processes like electroplating, bare copper wire can be used to suspend parts in the plating tank, conducting the necessary electrical current. Similarly, it finds application in stained glass projects for creating intricate designs. Even in experimental settings, such as developmental work with high-frequency radio antennas, the conductive properties of bare copper make it a useful material. These diverse applications underscore the versatility and fundamental importance of bare conductors in electrical and related fields.  

7. Advantages and Disadvantages of Bare Conductors

When comparing bare conductors with their insulated counterparts, several key advantages and disadvantages become apparent, influencing their suitability for different applications.  

Bare conductors offer the distinct advantage of higher electrical conductivity compared to insulated wires of the same material and size. This is because the absence of insulation allows for the entire cross-sectional area of the conductor to be utilized for current flow. They also exhibit better heat dissipation, as the heat generated by the current can be directly transferred to the surrounding environment without being trapped by an insulating layer. In many cases, bare conductors are lighter and less costly to manufacture and install, particularly in large-scale applications like overhead power transmission. Additionally, bare copper conductors are generally easier to solder, facilitating secure and reliable electrical connections.  

However, the lack of insulation also presents several disadvantages. Bare conductors offer no inherent protection against short circuits, requiring careful installation and separation to prevent unintended electrical paths. They are also directly exposed to environmental elements, which can lead to corrosion over time, especially in harsh or humid conditions. This vulnerability necessitates regular inspection and maintenance in exposed applications. The absence of insulation also limits the use cases of bare conductors to situations where insulation is not required for safety reasons, as direct contact can pose a significant risk of electrical shock or electrocution. Consequently, their installation often requires more stringent safety measures and adherence to clearance requirements. In some instances, bare conductors may also have a reduced mechanical load-bearing capacity compared to certain types of insulated cables that incorporate strengthening elements within their insulation or jacketing.  

In contrast, insulated conductors provide safe conductivity, minimizing the risk of accidental contact and electrical shock. The insulation layer can also offer protection against corrosion and environmental factors, extending the lifespan of the conductor in many applications. Insulated wires are generally easier to handle and install in a wider range of scenarios, including residential and commercial building wiring, and they often have a more aesthetically pleasing appearance when visible. Some insulated cables also offer better mechanical resistance to abrasion and physical damage. However, insulated conductors typically exhibit lower electrical conductivity compared to bare conductors of the same material and cross-sectional area. The insulation acts as a thermal barrier, hindering heat dissipation. Insulated wires are also generally heavier and more expensive than bare conductors.  

The decision to use bare or insulated conductors hinges on a careful evaluation of the specific requirements of the application. Factors such as the voltage and current levels, the operating environment, safety considerations, mechanical demands, cost constraints, and relevant regulatory standards all play a crucial role in this selection process.

8. Conclusion: Summary of Common Applications and Future Trends

Bare conductors are indispensable components in the electrical infrastructure that powers the modern world. Their unique properties, stemming from the absence of insulation, make them ideally suited for a range of critical applications. Primarily, they serve as the backbone of overhead power transmission lines, enabling the efficient and cost-effective delivery of electricity over long distances. Their ability to dissipate heat directly into the air is crucial for handling the high currents involved in these systems.

In electrical grounding systems, bare conductors, particularly copper, are essential for ensuring safety and protecting equipment. Their low resistance and direct contact with the earth provide a reliable path for fault currents and surges to be safely dissipated. Substations and switchyards rely heavily on bare conductors for busbars that distribute power between equipment and for creating comprehensive grounding grids that safeguard personnel and infrastructure.

While not the primary current-carrying elements in the windings of rotating machinery, bare conductors play a vital role in grounding and in the construction of specialized cables used with motors and generators. Their flexibility and conductivity make them suitable for these specific needs. Beyond these major areas, bare conductors are also critical in lightning protection systems, channeling the destructive energy of lightning strikes safely to the ground. They find applications in telecommunications for grounding and in specific cable designs. Even in specialized fields like welding, arts and crafts, and experimental work, the unique properties of bare conductors are leveraged.

Looking towards the future, ongoing research and development are likely to yield further advancements in bare conductor technology. Innovations such as high-temperature low-sag (HTLS) conductors and composite core conductors for overhead lines aim to improve efficiency and performance. The application of nano-coating technology to enhance corrosion resistance and extend the lifespan of bare conductors is another promising trend. Furthermore, the emergence of smart conductors with embedded sensors for real-time monitoring of temperature and electrical load could revolutionize the management and maintenance of bare conductor systems. These developments indicate a continued focus on enhancing the performance, durability, and safety of bare conductors in response to the evolving demands of electrical power systems.  

Table 1: Comparison of Common Bare Conductor Materials

Table 2: Advantages and Disadvantages of Bare vs. Insulated Conductors