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September 30, 2022
Local area networks (LANs) have historically been designed to ensure that all terminal equipment is within 100 meters (m) of a telecommunications room (TR) to comply with industry cabling standards. Now, with the adoption of smart building technology, more devices are connected to and powered by the network than ever before. Today's LAN environments often experience a situation where connected end devices are too far from the nearest TR to maintain the 100m distance limit.
It is well known that twisted pair copper cabling is a standards-based choice for connecting devices over 100m, but there is confusion in the industry about how far twisted pair copper cabling can reliably support at various transmission speeds and long-range power levels. To strategically address situations where equipment is located more than 100m away and reduce risk, information and communications technology (ICT) professionals need to understand the pros and cons of various options, the technical factors involved, and key considerations surrounding testing to help them identify Realistic and meet requirements.
Wiring Standard Compliant Options
The ANSI/TIA-568 cabling standard for commercial buildings defines minimum performance requirements for structured cabling to support various applications (eg, Ethernet, PoE, HDBase-T, DSL, etc.). These industry cabling standards are based on worst-case minimum performance of cabling system components, links and channels to ensure an objective, realistic and measurable basis for interoperability and competition in the marketplace.
Therefore, the ANSI/TIA-568 cabling standard has long specified a distance limit of 100m for horizontal twisted pair copper cabling channels, including a 90m permanent link and a total length of 10m patch cords. Keeping a fixed common horizontal channel length helps to infer performance parameters to support increased transfer speeds.
With the rise of IoT and smart building initiatives, devices in more spaces than ever need to be connected to the network. To cover outdoor spaces, warehouses, parking lots, and other remote areas, corporate facilities or campuses often require surveillance cameras, access control devices, wireless access points, or other equipment located more than 100m from the nearest telecommunications room.
To reduce cost and increase efficiency, many of these devices are now also digitally powered via remote powering technologies such as Power over Ethernet (PoE), rather than connecting to traditional AC power circuits. Cabling compliant options for connecting and powering equipment beyond 100m include adding new telecom rooms, using decentralized expander equipment, connecting equipment with fiber optic cables and powering them separately, or using hybrid copper fiber optic cables to transmit data and power . Each of these standards-based options has its advantages and disadvantages, as described below:
Adding a Telecom Room: One option for connecting equipment over 100m is to add another Telecom Room. This can be a real room, or a mini room installed in a freestanding or wall-mounted cabinet. The benefits of adding another telecom room include compliance with industry cabling standards, centralized management, and the ability to support speeds up to 10 Gbits/sec and deliver up to 90 W of PoE. However, if only a few remote devices located 100m away need to be supported, the cost of adding a new TR is difficult to justify. Not only does TR take up valuable real estate, but it also requires additional active equipment and associated power consumption, cooling, and maintenance.
Using Extender Devices: Deploying Ethernet extender devices in horizontal cable installations is another option to support remote devices. Extending the device is much less expensive than adding a TR, utilizes existing twisted pair copper cabling, and can support up to 10 Gbits/sec and up to 90 W of PoE, depending on the device. However, extender devices often require local power, which adds to the expense. Placing expander devices in horizontal spaces also increases remote points of failure and eliminates centralized management, which can make troubleshooting and maintenance more difficult and costly.
Connecting devices via fiber optic cables: Another option for extending the distance from devices in the LAN is to connect devices via fiber optic cables. According to the TIA standard, an OM3 or OM4 multimode fiber link can support 10 Gbits/sec to a distance of approximately 300m, or 1000 Mbits/sec to a distance of approximately 550m. While fiber is an ideal solution for these longer distances, the cost of fiber-optic transmission equipment is difficult to justify for some LAN equipment that is only 10 or 20 meters away from the TR.
Additionally, end devices with optical input/output (I/O) ports are limited in the market. Therefore, media converters and copper jumpers are often required for device connections. PoE media converters have the advantage of providing PoE power to devices, but using fiber optic cables with media conversion capabilities still requires higher cost of fiber optic transmission equipment.
Use a hybrid copper fiber optic cable: Even if the device does contain fiber ports for connecting it directly to the fiber network and doesn't require a media converter, if local power is not available, the device will need to have available power through other means than PoE . One option is to use a hybrid copper fiber optic cable, which includes optical fibers for data transmission and copper conductors for power transmission. Using a hybrid copper fiber optic cable still requires more expensive fiber optic transmission equipment, as well as a Class 2 limited power supply (LPS) to provide power. It is important to note that Class 2 power provided over hybrid copper fiber optic cables is not PoE. Although PoE is a Class 2 power source, it is only supported on twisted pair copper cables.
When using hybrid copper fiber optic cables, it is important to carefully select the size of the copper conductors, typically up to 12 AWG. The specification of copper directly affects how much power can be delivered over a given length. Additionally, using a Class 2 non-PoE power source over a hybrid copper fiber cable requires careful planning and voltage drop calculations to ensure there is enough power to support the device based on the device's current draw and distance from the power source. After deployment, if the conductors are too small or too far apart to support the power requirements of the end equipment, the only options are to replace the cable, add extra copper conductors, or shorten the link length. This could seriously hinder moves, adds and changes, and the ability to use hybrid copper fiber optic cables for future equipment.
more cost-effective approach
While not compliant with ANSI/TIA-568 cabling standards, the most cost-effective option for connecting equipment beyond 100m is to simply extend the distance of the twisted pair copper cabling. This approach requires no additional space, equipment or points of failure. Regardless of length, twisted pair copper cables also support the familiar modular RJ45 connection and installation practices - the installation process for longer links is no different than any other twisted pair copper cable, except that the cable is pulled 90 meters away from the TR. The use of twisted pair copper cables also supports centralized management for easy troubleshooting and maintenance, and enables efficient remote power supply via PoE directly from a PoE-capable switch.
When comparing the various options for connecting equipment beyond 100m from the TR, it is clear that the twisted pair copper cable is the most attractive from a cost perspective, as shown in the table below:
Although not standard compliant, twisted pair copper cable is the most cost-effective option for extending distances beyond 100 meters.
Technical factors involved
Although twisted pair copper cabling is the most cost-effective option for extending horizontal cabling distances beyond 100m, there are several factors that must be considered. Since the ANSI/TIA-568 cabling standard does not currently support extending the distance of twisted pair copper cabling channels beyond 10 m, it is necessary to review the application standard.
Cabling standards define minimum performance requirements for structured cabling links, channels, and components to support applications typically up to 100 m long, with the goal of ensuring interoperability between components from different manufacturers. Perform certification testing to cabling standards at installation, which is often a job scope requirement and warranties. Cable standard testing is performed on cables that are not yet actively supporting applications, connecting to equipment, or transmitting data.
In theory, cabling standards-compliant cables should ensure support for any application designed for use with that particular type of cable, up to a maximum length of 100 meters. In contrast, application criteria look at the ability of a specific application to operate on a link segment, regardless of cabling components and distance.
key performance parameters
Length-dependent performance parameters such as insertion loss, propagation delay, DC resistance, and signal-to-noise ratio (SNR) are closely related to the ability of a link segment to support a specific application of a specific length.
Insertion Loss – Measured in decibels (dB), insertion loss is the amount of energy a signal loses as it travels through the cable. If the loss is too high, the signal may not be strong enough to be properly received or interpreted by the connected active device. The farther the signal must travel, the greater the insertion loss. Connection points in the link add to the overall insertion loss. Insertion loss also increases with frequency and temperature. This is why the maximum allowable insertion loss for each cabling standard is higher for Category 6A specified at 500 MHz (42.8 dB) than Category 6 at 250 MHz (31.1 dB), Category 5e at 100 MHz (21.0 dB), etc.
Propagation delay - In a four-pair application, propagation delay (ie, the amount of time it takes to receive a signal at the far end of the link) increases with length and can vary from pair to pair. Measured in nanoseconds (ns), if the difference between the pair with the least delay and the pair with the greatest delay, known as the delay skew, is too large, it can cause bit errors that prevent proper data transfer. In video surveillance applications, excessive propagation delay is often seen as a jittery picture.
Too much difference between the pair with the smallest propagation delay and the pair with the largest propagation delay prevents proper data transfer
DC resistance - DC resistance is a measure of a conductor's ability to resist the flow of current. Measured in ohms (Ω), DC loop resistance is the DC resistance of two conductors of a pair of conductors that are looped (connected) at one end of the link. For PoE applications, the DC loop resistance defines the ability to supply power efficiently. According to the IEEE PoE application standard, the DC loop resistance of a pair of channels should be 25 Ω or less. Exceeding the DC loop resistance limit can adversely affect the ability of the PoE system to power and generate heat in the twisted pair copper cable, thereby increasing insertion loss. For a twisted copper pair to carry data with PoE power, the DC resistance of each conductor in the pair needs to be approximately equal. The difference in DC resistance between two conductors is called DC unbalance. If the DC imbalance is too high, it may cause distortion of the data signal, resulting in bit errors that prevent the normal transmission of data.
Signal-to-Noise Ratio (SNR) — SNR is a relative measure of the signal power compared to the noise power in a specific frequency range. In dB (like insertion loss), the higher the signal-to-noise ratio, the better the signal quality. SNR is directly related to insertion loss - lower insertion loss increases SNR, and since insertion loss increases with distance, SNR is also affected by the length of the cabling link. Too low an SNR can reduce the supported transmission speed or require a reduction in link length.
key influencing factors
Insertion loss, DC resistance, propagation delay skew, and SNR can affect how far a twisted pair copper cable can support a given application, and these factors can be affected by several factors—from speed and PoE levels to cable construction and quality, and design and installation variables. All of these factors are why there is currently no industry cabling standard for extending distances beyond 100m over twisted pair copper cables.
Transmission Speed and PoE Power Level - Faster transmission speeds operate at higher frequencies, which increases insertion loss. Due to the voltage drop, the PoE power available at the end device also decreases with distance. Therefore, the faster the speed and the higher the power, the shorter the distance that the twisted pair copper cable can support.
Cable and Jumper Construction - Insertion loss and DC resistance are highly dependent on the size of the conductors in the twisted pair copper cable. The larger the gauge, the lower the insertion loss and resistance. Furthermore, stranded conductors, such as those used for patch cords, exhibit higher insertion loss than solid copper conductors. Shielding, and even the dielectric materials used in cable insulation and jacket materials can affect insertion loss and DC resistance.
Cable and patch cord quality - Inconsistent pair geometry and twist rates and variations in copper conductor diameter, concentricity, profile, and smoothness can cause DC resistance unbalance and propagation delay shifts that affect distance capability. DC resistance is also a problem with low-quality and often counterfeit copper-clad aluminum cables and jumpers. Aluminum has over 66% higher DC resistance than copper, which easily exceeds the 25 Ω limit for PoE applications and also generates excessive heat. Therefore, copper-clad aluminum cables do not meet industry wiring standards and do not meet the UL Safety List of the National Electrical Code (NEC®).
Network topology – how devices are connected to the network (ie, directly using modular plugs to terminate links or through receptacles and patch cords), the total number of connectors in a channel affects insertion loss and distance capability. The more connections in a channel, the greater the insertion loss.
Heat and Temperature - Heat generated by DC current in PoE applications, overall ambient temperature, and the ability of the cable to dissipate heat can all create thermal rise in twisted pair copper cables. This added heat increases insertion loss. In cable bundles carrying higher levels of PoE power, heat is more difficult to dissipate. Industry standards and NEC® address heat rise in cable harnesses carrying DC current by limiting harness size. For a 100m twisted pair copper channel length, industry cabling standards specify an ambient operating temperature of 20°C (68°F) and recommend reducing (derating) the channel length at higher temperatures.
Poor workmanship - Improper installation practices such as exceeding cable bend radii, compressing or kinking cables, not consistently terminating all conductors, or not properly maintaining pair twists at termination points can increase DC resistance unbalance and propagation Delay bias, thereby limiting distance capability.
What is the reality?
There are several IP-based network devices that operate at lower speeds (1000 Mbits/sec or less) and require lower levels of PoE power. Devices such as surveillance cameras, phone booths, access control panels, PoE lighting, clock systems, intercom/paging systems, energy management systems, and environmental sensors and controls are examples of low-speed, low-power devices that typically need to be located above 100m.
For example, it may be necessary to install surveillance cameras outside a warehouse, an access control panel at the far end of a factory, or an emergency call box in a parking lot. At lower speeds and lower PoE power levels, performance factors such as insertion loss and voltage drop are less likely to affect distance capability.
Additionally, most well-known manufacturers have designed twisted pair copper cabling systems that exceed cabling standards and offer greater margins, including improved insertion loss, propagation delay, and DC resistance. While this helps ensure support for 100m applications regardless of installation variables and environmental factors, it also allows several well-known manufacturers to certify certain twisted pair copper cables to support various Low speed, low power applications, many of these advanced cables are even advertised as offering longer distances for specific applications.
Unfortunately, while many high-quality twisted-pair copper cabling systems can support lengths in excess of 100m, there is still a lot of confusion in the industry about how far they can reliably support at various transmission speeds and long-range power levels. Much of this confusion stems from the fact that some manufacturers claim to be able to support extended distances for high-speed, high-power applications, but are based on inadequate methods to test and validate performance at various lengths. The reality is that supporting Type 3 (60 W) and Type 4 (90 W) PoE transmission speeds of 10 Gbits/sec and higher for extended distances is extremely challenging, even for reputable innovative manufacturers . Applications that require these higher speeds and PoE levels, such as emerging high-throughput WiFi 6/6E deployments,
When considering using twisted pair copper cables to extend distances beyond 100m, it is important to take a close look at the claims by verifying the manufacturer's cable specifications, understanding testing requirements, identifying risks and asking the right questions.
Learn about testing requirements
When choosing a twisted pair copper cable for distances in excess of 100m, it is important to review the manufacturer's specifications and understand how the cable is tested. Well-known manufacturers test their cabling systems for compliance with the minimum performance requirements of the Cabling Component Standard. This ensures support for any application designed to run up to 100m over that particular cable type (ie Category 5e, Category 6, Category 6A, etc.).
Installers then field test the cable equipment against cabling standards to ensure that the installed links also meet the performance and distance requirements to support the application designed to run on the specific cable. However, compliance with cabling standards does not indicate whether these cables will support applications beyond 100m. This is where application testing comes in.
Well-known cabling manufacturers perform rigorous lab testing and third-party distance verification according to IEEE application standards (i.e. Ethernet, PoE, etc.) and various conditions such as topology, ambient temperature, and end device requirements. They also conduct lab bit error rate (BER) testing using device-specific network interface cards (NICs). A BER test sends actual Ethernet packets in both directions at a specific speed to check for errors. It is through this comprehensive testing methodology that many well-known manufacturers are able to guarantee twisted pair copper cables for specific applications and distances in excess of 100m.
Cabling standards define minimum performance requirements for structured cabling to support applications over 100m, while application standards look at the ability of a specific application to operate over a link segment, regardless of cabling components and distance. BER testing is done under specific conditions with specific equipment, which is more suitable for engineering solutions.
Application testing can also be performed on-site and is recommended for twisted pair copper cables with channel lengths greater than 100m. Application testing reduces risk by ensuring that applications are supported at specific distances. BER testing can also be performed in the field, but unlike application testing, it evaluates a specific device at a specific distance and under specific conditions. In other words, BER testing is better suited for evaluating engineering solutions, which can fail if any of the variables, including equipment, temperature, external noise, and other factors, change.
Recognize the risk of variation
For anyone considering twisted pair copper cabling to connect devices over 100m, it's important to understand that each device is unique. Equipment manufacturers design switch ports and equipment to meet the minimum requirements for successful transmission within the limits of the application link segment, which can easily be achieved with 100m of cable.
However, the ability of each device to accommodate transmission irregularities associated with extended distances may vary. This means that a long-distance link that successfully connects two specific devices may not function if one of the devices changes. Even with equipment from the same vendor, but with different types of equipment.
The variability that occurs in long-distance links creates uncertainty, which is why application testing is so important—whether in the lab by cable manufacturers or in the field. Replacing equipment and changing conditions does not guarantee performance if only BER testing is performed, eliminating future-proofing.
ask the right questions
Given the variety of variables that affect distance capability, as well as the various marketing propositions in the industry, it is important to ask the right questions when choosing a twisted pair copper cable for long distance deployments. This is especially true for suppliers who claim their cables can support higher transmission speeds and PoE levels that seem too good to be true and/or far beyond the specifications of trusted, reputable manufacturers.
For example, adhering to the following guidelines can significantly reduce risk:
Ask the cabling manufacturer what type of testing has been done to determine advertised distance capability for specific application speeds and PoE levels. Buyers need to take note if rigorous lab-based application testing and BER testing are not performed. If only BER testing is done, understand that changing equipment or a single variable may prevent the link from functioning. Make sure to also ask for any test documentation as evidence.
Find out if the cable is covered under warranty, distance, application and PoE level, and what type of field testing is recommended or required to maintain warranty. While most reputable manufacturers will insist on warranties, as long as the permanent link tests pass all application criteria-based parameters (except length), it is advisable to always check specific warranty requirements for long-range deployments.
Ask the cabling manufacturer to simulate your specific environment, equipment and configuration to ensure it will function properly prior to installation. This is especially important for cabling manufacturers who cannot produce adequate application test results and/or offer no warranty. If there is any uncertainty about the ability of the manufacturer's cable to support the application and deliver the required level of PoE over a certain distance, it is best to look elsewhere or choose a standards-based solution to extend the distance.
Not long ago, we also saw the establishment of cabling standards, and now, the entire industry cannot function without these standards. While industry standards are currently unable to address long-range deployment due to a variety of variables, there is light at the end of the tunnel - we are seeing a trend towards long-range standards that will help remove confusion in the marketplace and prevent manufacturers from creating unauthorized Test supported marketing claims.
Collaborative efforts between several cable manufacturers, standards bodies, and distributors have helped to establish validated measurement methods to assure results and protect the design intent of the extended range of standards-based installations. The new Single Pair Ethernet (SPE) standard supports low-speed devices from 10mbit/sec up to 1000 meters with PoE up to 13.6 W, and may eventually also address sensors, actuators, relays and sensors used in building automation systems and some security deployments. The need to connect larger distances between controllers. To achieve this, equipment vendors need to integrate SPE technology into their chipsets.
At the same time, anyone looking to extend distances beyond 100m in twisted pair copper cable should speak to their cable manufacturer and ask the right questions to verify performance before investing. If marketing claims seem far-fetched, look for a reputable cable manufacturer who sticks to empirical evidence and guarantees the application and power levels of their cables to practical distances.
Considering that even the best known and most innovative manufacturer's twisted pair copper cables are typically unable to support 1000 Mbits/sec or higher at up to 90W Type 4 PoE for physical reasons, well over 100 m . For low-speed 100-Mbit/sec applications involving multiple device types, distances can be much higher than 100m, especially at low PoE levels. For many low-speed devices, extending distances beyond 100m using twisted pair copper wire from well-known manufacturers is risk-free and cost-effective. But at the end of the day, anyone looking to choose a twisted pair copper cabling system for distances over 100m should do their own due diligence.