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PoE Troubleshooting: Common Problems and Solutions

PoE has become a critical technology in this highly connected world of today to simplify data networking and power management in networks of all types. Its ability to transfer data and power through the same network cabling opens a realm of new possibilities to satisfy the ever-growing requirements of today’s Internet of Things (IoT). As the number of network devices continues to soar, the deployment of PoE has become a necessity to power everything from VoIP phones, security cameras, wireless access points, and Point-of-Sale (POS) terminals to digital signage, All-in-One touchscreen PCs and remote access control systems. One of the most obvious advantages of using PoE is that it cuts down the volume of cables used and eliminates the material and labor costs to install new AC outlets. Powerful as it is, PoE is not without its frustrations. In this blog, we’ll elaborate on the common issues in PoE networking and give you the best possible solutions to tackle these problems.

Problem 1: PoE Stops Working When It Hits 100 Meters

Although PoE provides a convenient and cost-effective way to deliver both power and data connectivity over a twisted-pair cabling system, one of the most significant challenges when deploying PoE is its physical reach since PoE can only a maximum transmission distance of 100 meters/328ft. Beyond this range, you’ll experience severe signal degradation and voltage drop. As electricity travels down the cable, it will generate an invisible electromagnetic field that disrupts data transmission, and accordingly, the network speed will drop to 10Mbps or less. However, PoE devices are often located at longer distances from the nearest network switch or power outlet, requiring an extra switch to reach extended distances in places where 100 meters is far from enough. Moreover, as the distance increases, the DC resistance will also increase and cause insertion loss.

Top 4 Methods to Extend PoE over Long Distances

To overcome the geographical limit of standard PoE, we’ll introduce 3 methods to help you install PoE devices over 100 meters.

1) PoE Extender

One of the most straightforward ways is to deploy a PoE extender. It leverages existing twisted-pair cabling to deliver the electrical power to the next device down the line so as to establish a long-range network connection between two geographically separate network devices. By daisy-chaining two PoE extenders, the maximum distance can reach 300 meters to help you connect isolated workstations within the building. Fastcabling has launched a direct-burial PoE extender kit that allows you to extend the distance up to 500 meters by connecting the inputs of both extenders together (the maximum distance between two extenders can reach 300 meters) so as to eliminate failure points over long cable runs.

2) PoE Powered Switch

If you wanna install more PoE devices at extended distances, you can also use a PoE powered switch to extend the range for another 100 meters. The PoE powered switch can receive power and data from an upstream PSE (PoE switch or PoE injector) and deliver them to connected PDs. It provides central management solutions for enterprise network users to manage their IP devices remotely. By using the PoE powered switch, fewer cables will be needed during the installation, which highly reduces the materials and labor costs. Moreover, it can also be applied in hard-to-reach places, such as closets, ceilings, basements, or some places where the existing power outlets are already occupied for other uses. But to deploy the PoE powered switch, you’ll need a high-power PSE to ensure it delivers its best performance.

3) PoE Switch with CCTV Mode

If possible, you can also activate the CCTV mode/VLAN function on your PoE switch to break the 100-meter limit of standard PoE without installing any active device along the way. Most PoE switches come with two operation modes: Default and CCTV. In the Default mode, a single PoE port can support a transmission speed of 10/100/1000Mbps within 100 meters. But when the CCTV mode is enabled, the distance can be extended to 250 meters, and no hardware and configuration are necessary. But as a compromise, the network speed will be reduced to 10Mbps, so this solution is only applicable in installing devices that have a low bandwidth demand like fixed IP cameras.

4) Long-Range PoE Switch

For longer-distance deployments, you can also implement a long-range PoE switch to install the devices at farther distances without the constraints of AC outlets. The use of long-range PoE switches eliminates the need for additional switches or repeaters for long-distance connections since the connections between the PSE and PDs can be completed by cables only. The bandwidth of most network switches will drop to 10Mbps and even lower when it exceeds the 100-meter limit. But the long-range PoE switch can extend the transmission distance to 500 meters with the network speed being 100/10Mbps and it can remain at 10Mbps when the distance hits 800 meters, ideal for installing 4K cameras or other network solutions in parking lots, garages, cross-building applications, etc.

Problem 2: PoE Devices Fail to Power Up

PDs failing to boost up is one of the most frequently seen problems in PoE troubleshooting. There is a wide variety of reasons that account for power failure, but the main reason is often the insufficient power supply. Normally, the active PSE will detect if the connected PD is PoE-compatible automatically and evaluates how much power the PD requires. If the PSE cannot provide sufficient power to the PD, the PD will not get powered. And since most PSEs cannot deliver the exact amount of power that PD requests, they will automatically demote the PDs to a lower power class. For example, if you connect a Class 8 PD to a Class 5 PSE, chances are higher that the PSE will shut down the PD for taking too much power. And with the influx of new designs, more and more network devices require more power than what the legacy PoE standards can deliver. In the previous IEEE802.3at standard, the PSE can only supply power of 30W with the remaining power available at the PD being 25.5W max., while in some old-fashioned PTZ cameras, a separate power source is often needed to power the heater or blower since the camera itself would consume 30W.

Get More Power with High-Power PSEs

Fully compatible with legacy PoE, a new-generation PoE standard IEEE802.3bt, also known as high-power PoE, first-ever implements power over four twisted pairs of structured wiring to minimize power loss with a substantially increased power budget. 2 new PoE types have been introduced in the new PoE standard: Type 3 can provide up to 60 watts of power at each PoE port (maximum power available at the PD is 51W), while Type 4 can supply maximum power output of 100W and 90W at PSE and PDs respectively to support power-hungry applications including RFID readers, 802.11ac WAPs, All-in-One PCs, information kiosks, thin clients, etc. Moreover, high-power PoE shows great improvements in standby power consumption to reduce the minimum standby power from 200mW to 20mW.

To satisfy the increasing demands of high-power devices, Fastcabling has launched various types of high-power solutions to a high-power network system at ease.

1) 802.3bt PoE Switch

This 802.3bt PoE Switch has 6*10/100/1000Mbps PoE Ports, 2*1Gbps Ethernet ports and 2* 1Gbps SFP slots. It features a total power output of 120W to provide a maximum power supply of 90W on ports#1-2 (the rest of PoE ports#3-8-30W), ideal for integrating different network devices with different power requirements on the same PoE switch. It offers a cost-effective method to install power-hungry network devices, such as high-power WAPs and digital signage displays, in places where there is no power source present. It’s an unmanaged PoE switch that features a plug-and-play installation with easy configuration. It comes in a compact design, ideal for space-constrained applications.

2) 10 Gigabit 95W PoE Injector

The 10 Gigabit 95W PoE injector offers a cost-effective solution to power multiple high-power devices, such as 802.11ac/ax wireless access points, high-definition PTZ cameras and LED lighting, with a significantly increased power budget at 10 Gigabit network speed with less latency. The high-power PoE injector can provide a maximum of 95 watts of power by using all 4 twisted pairs. It can be utilized to connect PoE and non-PoE devices using a single Cat5e/6 or higher-level Ethernet cable with a minimal impact on the existing network infrastructure. The wall-mountable injector features a simple plug-and-play design, offering great convenience and flexibility on installation. It is an energy-conscious supplementary device with lower power consumption.

Problem 3: Connected Devices Are Burnt Out

Most of you must have run into the situation that the connected devices are burnt out for no reason. If you are certain that your network equipment has no quality problems, you will need to confirm if PSE and PD are both compliant with the IEEE802.3 standards, because if you plug a device into non-standard or passive PoE, the chance has it that the PD may stop working and even damage when it connects a wrong voltage. In passive PoE, power is always present on the PoE port, which means it always sends unnegotiated power out over the Ethernet cable to the connected device at a certain voltage regardless of whether it is PoE-compatible or not. If you connect the device to the wrong power source, your equipment may not boost up if the voltage or current will be lower than required for the application, and permanent damage is also possible if the voltage is too high.

Confirm the Voltage Beforehand or Use Active PoE Instead

When using a passive PoE switch, it’s important to make sure the connected device supports PoE before powering it up via a PoE power supply. Moreover, to reduce the risks associated with passive PoE, you should ensure the PSE provides the correct voltage for the PD. For example, if you send 30 watts of power to a camera that only handles 15W max., then the camera will easily get damaged. Always check the specifications of PD, know what wattage it requests and ensure the PSE can provide the required power to that workload. But its drawback is that the passive PoE switch only accepts devices that belong to the same power level, which will be problematic when you need to mix different types of devices on the same switch.

Therefore, the best solution is to deploy active PoE. Active PoE requires more intelligent communication between devices to negotiate the proper voltage between the PSE and PD. Active PoE switch will do a ‘power handshake’ to detect if the PD supports PoE and evaluate power requirements before actually supplying power to the PD to avoid powering devices that are not designed to the standard. The handshake is normally composed of three stages: detection, classification and operation. The PSE will send a low voltage pulse (2V-10V) to the PD to see if it’s PoE-enabled and measure the amount of power each PD needs before it sends any power out. And if the power handshake fails, no power will be delivered. However, in passive PoE, there will be no such verifying procedures.

Problem 4: PoE Devices Are Damaged in Outdoor Applications

The lightning strike is a serious concern when deploying network devices outdoors, especially for mission-critical applications, i.e. IP camera systems. Even though lightning strike is not common and is largely environmentally impacted, excess current or voltage can also damage the equipment. Even if the devices are installed indoors, unfortunately, they won’t be completely safe because electromagnetic waves induced by lightning can still interfere with the connected devices. Moreover, rain is another problem in outdoor deployment when moisture gets into the connection between the device and the Ethernet cable, which will cause corrosion on the metal pins and hinder both power and data transmission.

1. Protect Your Devices from Lightning with Surge Protectors

If you’re using network devices outdoors, you should always take some precautions to protect your devices and appliances from power surges. Installing surge protectors is an important preventive measure to protect your PoE devices from over-voltages. Physically, a surge protector mainly has two functions: one is to keep the surge voltage within a safe threshold so that the dielectric strength of the PoE device will not be exceeded; another is to discharge the excessive currents to the ground. Fastcabling has launched various surge protectors to protect outdoor devices from power surges:

Din Rail Industrial RJ45 PoE Surge Protector

This Din-Rail industrial RJ45 PoE surge protector is a compact surge protection device that features 16kV surge protection to efficiently mitigate the negative effects of lighting spikes and surges in long-run copper cabling. It complies with standard PoE and works with no problem This surge protector supports Din-Rail mounting, so 5 or more such protectors can be installed side by side as integrity in a 19″ wide Din-Rail mounting rack for chain setups, which makes grounding more convenient and affordable, ideal for small-to-medium sized businesses. It is backed up with a wider working temperature range from -40℃ to 85℃.

2. Simple Ways to Protect Your Devices from Water Damage

Water damage can be avoided with a little extra care. Here, we’ve introduced several methods to help you protect your devices from water ingress.

1) Select the Correct Ethernet Cables

When choosing an appropriate network cable for your project, the outdoor Ethernet cable is always the best option. For safe operation, you should choose one that is waterproof, shielded with a UV-resistant jacket designed to withstand UV exposure, snow and ice. And it’s highly recommended to use direct-burial type cables that can be buried directly under the ground without conduits. But if you have to use the conduits, we do not recommend you to lay the cables in the PVC conduits since the water vapor could easily penetrate and linger in such materials, which will gradually damage the network cables in the long run.

2) Prevent Water Damage to Your Connections

Waterproofing outdoor PoE devices require the Ethernet cables to be tightly sealed. The simplest way is to use a waterproof connector shield: just run the cable through the hole and seal it with a rubber grommet and secure a bit of silicone. Or you can simply use a rubber sleeve to protect the connection from rain and water splash. Moreover, you can use a junction box to provide protective housing for the cable so as to ensure no moisture can get through.

3) Use an Outdoor PoE Switch

A reliable power supply and network connection are crucial for outdoor network installation. When deploying PoE switches in wash-down areas, water protection is ultra important. To ensure the continuous operations of your outdoor cameras, you’ll need to deploy an outdoor PoE switch. The outdoor PoE switch is manufactured and tested to the industrial standards for operation even in applications that require the highest level of reliability. With a rugged waterproof design, the outdoor PoE switch provides a safe and stable network connection outdoors. Fastcabling has launched an outdoor PoE switch that is built with an internal power bank and is able to work with various kinds of external power supplies like AC 100-240V (the voltage range at 802.3at mode is DC 53V), solar power, etc., to guarantee the continued operation of the outdoor PoE switch and connected devices at greater distances.

Problem 5: Heat Rise Concern Rises in High-Power PoE

Heat rise is a severe concern in high-power PoE. Simply put, more power means more heat, and overheating will increase the DC resistance in copper wires, thereby jeopardizing the signal transmission. The higher the power level and the smaller the gauge of the cable, the more likely the cable heats up, which will accelerate cable deterioration and the aging of the jacket. Overheating in PoE cabling can also lead to an increase in insertion loss. To minimize heat rise in high-power PoE, you should choose a network cable of a higher category: the higher the cable category, the lower the heat rise. Normally, a Cat6 or 6e Ethernet cable would suffice the job. And you can choose a cable terminated with a larger conductor since conductor resistance is one of the main culprits of overheating. A larger conductor will let electrical currents easily flow through and thereby reduce the conductor resistance. And it’s advised to choose a shielded cable rather than an unshielded one for better heat dissipation.

Problem 6: Devices Fail to Deliver the Network Speed as Promised

Another commonly seen problem in PoE networking is that our PoE devices fail to deliver the expected network speed. A possible reason will be your cabling since not all equipment works together well. If you connect a Cat3 cable to Gigabit PoE, since such a cable can only support a maximum speed of 10Mbps, then the connected PD can run at 10Mbps only. So you’d better use higher-category cables for Gigabit Ethernet networks. Cat5 Ethernet cable can support a network speed of 10/100Mbps with a bandwidth of up to 100MHz, while the speed of Cat5e is up to 1000Mbps, ten times faster than the Cat5 network cable. Besides, it decreases crosstalk, which makes it the most widely used category on the market. Moreover, Cat6 is certified to handle Gigabit speed with a bandwidth of 250MHz. And it has better insulation and thinner wire, making it suitable for high EMI environments.

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