Power over Ethernet Extenders - Technology Explained

How to extend the PoE distance?  How do Power over Ethernet extenders work? On this page you will learn everything there is to know about PoE repeaters and extenders.

What is a PoE ExtenderWhat is a PoE Extender
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What is Power over Ethernet?

 Power over Ethernet (PoE) allows for installation of network devices including outside equipment without having to connect to AC power. PoE technology passes electric power and data over regular Cat5e (or better) network cable, which allows power to be delivered to remote areas without the need to install additional electrical infrastructure such as power outlets for every edge device.

Read more about Power over Ethernet (PoE) here.

What are limitations of Power over Ethernet?

PoE technology is based on the rules and standards of Ethernet networking and therefore is subject to the same limitations. Generally, the maximum length of an Ethernet cable per ANSI/TIA-568 cannot exceed 328 feet, or 100 meters.

To connect networking devices that are further away than that, Fiber Optic cables can be used. Using Fiber cables, in combination with SFP transceiver modules and media converters, long-range connections of well over 10 miles can be established. However, since Fiber Ethernet cannot be used for Power over Ethernet, the only way to connect a PoE edge device to a network that is further than 328 feet away is to extend the PoE distance utilizing a Power over Ethernet repeater, or PoE extender. 

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What is a Power over Ethernet Extender?

Power over Ethernet (PoE) extenders or PoE repeaters can extend the connection distance between the PoE Injector or PoE switch (PSE) and the PoE edge device (PD) . The PoE extender is installed in-line between the PSE and the PD. Each side the connection distance can be 100 meters (328 ft.). Some PoE extenders allow you to daisy-chain multiple units, pushing the total connection distance past 500 meters (1640 ft.).

PoE Extender versus PoE Switch without Extender

What else is there to know about Power over Ethernet Repeaters?

  • These devices are Plug and Play.
  • PoE extenders exist for indoor and outdoor applications. Some models provide IP6x ingress protection, and some even impact protection (IK).
  • Not all Power over Ethernet repeaters can be cascaded.
  • Not all PoE extenders support Gigabit speeds. There are still Fast-Ethernet products available.
  • PoE extenders are available with one, two and four ports.
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How can PoE Extenders be Daisy-Chained?

A Power over Ethernet Repeater receives power and data from the PoE switch or injector. While it uses some of that power for itself to operate, it can pass the remaining power to the next PoE device down the line. A Gigabit PoE extender will consume 4 to 5 watts. If connected it to an IEEE 802.3at PoE+ injector that can deliver roughly 25 watts of power to the extender, you will have approximately 20 – 21 watts available for your connected PoE device. If you cascade PoE extenders, you will lose four to five watts per repeater. The table below shows the relationship between power availability and the number of PoE extenders used.

Number of extenders Distance Power available from PSE (input)Maximum power for PD (output)
1656 ft25 W20 W
2984 ft20 W15 W
31,312 ft.15 W10 W
41,640 ft.10 W5 W

PoE Extender Distance Considerations

Exactly how far you can extend the PoE connection depends on various factors.

  • Type of PoE extender (1): Ultra PoE Extenders can take from 60 to 90 watts of power and whereas High-Power PoE+ Extenders are typically limited to an input of 30 watts. The higher the input power, the further you can extend the signal by means of cascading more PoE repeaters.
  • Type of PoE extender (2): First, not all PoE repeaters can be daisy-chained, and second, the amount of power the extender draws varies. Special attention should be paid the the technical specification of the PoE repeater.
  • Type of PoE (PD) device: The maximum power consumption of the PoE device you wish to connect is a crucial factor. Typically this information can be obtained from the technical specifications of the device, but sometimes you may need to contact the manufacturer.
    Tip: Be conservative and leave enough room for error. For example, if the technical information of a PoE network camera specify 18 watts maximum power consumption, calculate with 20 watts to be on the safe side.
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Alternatives to PoE Extenders and Repeaters

Power over Ethernet Repeaters typically offer only one or two RJ45 ports. In situations where more ports are required, there are other choices.

1. Extend-Mode PoE Switch

These are unmanaged Power over Ethernet switches that have the capability to extend the connection distance from 100 m (328 ft.) to 200 m (656 ft.) or even more. The trade off is that when the extend mode is activated, the Ethernet connection speed drops to 10 Mbps. That may have a distinct "1990s" sound to it, but the reality is that even today, 10 Mbps is fast enough for the majority of applications. Extend-mode or long-range PoE switches typically feature a manual toggle switch to activate the mode, for either all or select ports.

2. PoE Passthrough or PoE-Powered Switches

This is a special type of PoE switch that gets its power from an PoE switch or injector and makes power available to other PoE devices, such as VoIP phones and cameras.