Power over Ethernet (PoE) provides a convenient and cost-effective approach to achieve both power and data connectivity on a single connection. However, since it is an Ethernet channel, it’s highly restricted by the 100m distance limit. Thus, PoE extension is ultra important to achieve long-range Ethernet deployments. In this article, we’re gonna unveil the myths and truths about PoE extension.
#1 Why is the transmission distance limited to 100 meters?
Theoretically, PoE can power any device, whether it be PoE-enable or non-PoE devices using a PoE splitter, at any reasonable distance if sufficient voltage reaches the terminal devices, but a single Ethernet cable is designed to work over a maximum distance of 100m/328ft in a twisted-pair cabling system (802.3 standards). Beyond this inherent limit, signals will become indiscernible and distorted. There are two main reasons for signal degradation over Ethernet: wire resistance and interference. Data transmission is accomplished in the form of electrical signals in a copper-based connection, where all the electronic signals transmitted through the metallic conductors will be impacted by the DC resistance of varying degrees. The resistivity of the wire basically depends on its length and temperature. Normally, the resistance goes up as the distance increases. And conductors like copper have a positive temperature coefficient (PTC), indicating an increase in temperature comes along with the increase in resistance, so the increased heat generated by higher voltage will cause signal attenuation and distortion. Additionally, the electromagnetic fields generated by the flowing electricity will also lead to severe signal loss during the transmission. When exceeding the standard 100-meter reach of Ethernet, the signal attenuation will intensify due to the prolonged exposure to EMI. And the insulation shielding around the cable will inevitably absorb signals, so the deterioration will get worse over the long run.
#2 Why does the IP camera stop working after 100 meters?
In some cases, the PoE-enabled devices will stop functioning after 100 meters, provided there is no short-circuit or physical damage detected on both ends. So what causes the shutdown of the terminal device? Well, there are two possible factors that may account for the malfunction of PoE devices, namely the voltage drop and failure in data transmission. Voltage drop is a common issue in long-run cabling, in which situations the measured power delivered by the power sourcing equipment (PSE) is higher than the power available at PDs. The voltage drop is caused by the DC resistance, which will grow in proportion as the distance increases, and dissipated in the form of heat. As the distance increases, so does the power loss. According to the IEEE 802.3 standard, a relative power loss of 15% is normal, while a substantial drop in voltage will threaten the ongoing functionality of the terminal devices. When the IP camera (installed 500 meters away from the PSE) requires more power that exceeds the actual power supply available at the PD, it will stop working due to energy deficiency. What’s more, since 802.3af/at only supports data transmission at a maximum distance of 100m/328ft, when using a standard PoE switch with a Cat5/6 Ethernet cable, the IP camera will fail to send back the footage to the network video recorder (NVR) over the long cable runs. And it should be noted that Cat7 cable, though advertised for its 100 Gbps speed, is only limited to 15 meters (about 49 feet), and beyond that limit, it’ll drop to 10 Gbps as other Cat6a cables.
#3 RJ45 inline coupler vs PoE repeater: which to choose for PoE extension?
RJ45 inline coupler and PoE repeater are widely used solutions in the past decade to extend to the overall length of the Ethernet cable, but which one is suitable for your applications?
The RJ45 inline coupler offers a practical, cost-effective solution to bridge the gap between two Ethernet cables that share the same bandwidth with two RJ45 ports to extend the existing cable length, but it is only a temporary solution in connectivity, an emergency measure when the cable is broken or the cable cannot be immediately replaced, because it doesn’t provide any amplification or signal boost feature to improve the network performance. In short terms, the coupler only extends the length of the cable, while still restricted by the 100-meter limit. Besides, wrong termination and loose connection will degrade the signal and reduce the reliability and speed of the whole cable. Not to mention that the couplers are made of plastics, they will break over time owing to oxidization.
The PoE extender is one of the most effective ways to repeat the signals and re-transmit them to the PDs before signal degradation exhibits, forming a seamless connection. It receives the power and data transmitted from the PSE, uses some of the power to operate itself (a Gigabit extender consumes 4-5 watts of power) and transfer the remaining power to the next device (i.e. \PoE extender or terminal device). As a user-friendly technology, it features a simple plug-and-play design. The direct burial PoE extender from Fastcabling provides reliable and stable power and data connection in long-distance deployments in outdoor environments. By using two PoE extenders, the maximum distance can be extended to 500m/984ft (the distance between the extenders is 300 meters).
#4 How to realize long-range Ethernet?
- PoE extender
As previously mentioned, the PoE extender is one of the most effective ways to surpass the standard 100-meter Ethernet limitation. Unlike the RJ45 coupler, it can repeat and re-transmit the signals along the long cable runs to eliminate the deployment of any active devices. The extender does not require any power supply (no AC outlets needed), featuring simple plug-and-play installation. The PoE extenders from Fastcabling can be directly buried under the ground with a high IP rating of IP67 to protect the equipment from water penetration and dust ingress. A pair of PoE extenders can be deployed to achieve the long-range deployment of up to 500 meters by connecting one PoE extender’s input port with another PoE extender’s input port with a 300-meter-long Ethernet cable. Here is a buying guide to help you select the suitable PoE extension devices: How to Choose the Best PoE Extension Devices?
- Long-range PoE switch
Another method is to deploy a Gigabit long-range PoE+ switch to extend Ethernet without additional equipment so as to address the challenges of powering remote devices. The PoE technology is a cost-effective approach to deliver power supply and data connection to the powered devices via a single Ethernet cable. The PoE+ switch is the updated version of the regular network switch with higher power output and bandwidth to secure long-distance Ethernet deployments. The 800m 8-port long-range PoE+ switch (10/100/1000 Mbps) from Fastcabling with a total power budget of 120W can support nearly 23 watts of PoE power on a per-port basis over a distance of up to 500 meters overcoming the 100-meter limit of the Ethernet cable (30W at 100 meters). The long-range PoE+ switch can still achieve 100 Mbps at 500 meters (10 Mbps at 800 meters) to provide enough bandwidth to power some terminal devices such as security cameras and VoIP phones. It has two uplink ports with a transmission speed of 1000 Mbps to ensure high-speed data transmission. The long-rang PoE switch can be used with RJ45 couplers and PoE extenders to extend the distance up to 800 meters.
- Fiber optic system
Fiber optic technology has overcome the geographical and operational challenges of long-distance deployments with a maximum distance of up to 80 km. It barely experiences signal attenuation or distortion, and thereby eliminates the need for re-transmission. Additionally, the fiber cables transmit light signals in data transmission which enables them to operate at a fast speed (1000 Mbps/s) with significantly higher throughput than the copper cables. Fiber cables are highly resistant to water, dust or other penetrative elements and immune to EMI. Moreover, fiber optic internet is a long-term, future-proof technology with a prolonged lifespan of 50 years. You can easily set up a fiber optic connection by using a pair of media converters on both sides. Media converter is a useful device to convert digital signals to optical signals, and vice versa. The regular media converter is designed for data communication only, while the PoE media converter could deliver both power and data to the terminal devices.
- Wireless network bridge
The wireless network bridge is specially designed to build the high-speed point to point or point to multipoint wireless data transmission for up to 3 km by connecting two segments of network together. It allows the non-wireless devices to connect to the wireless network via a wired connection to the network bridge, thereby eliminating the need for complicated and expensive cable wiring. If you have a network printer that can’t be connected to the WiFi directly, the bridge can convert the WiFi signals to the wired signal and transmit it to the printer. It can be applied for outdoor deployments in harsh environments, such as oil pipeline, or other combustible and inflammable areas, with a certified IP65 protection. So, with the help of the network bridge, you can easily extend the Ethernet beyond 1 km.
