What is a PoE Injector? A Basic Guide to Understanding How It Works and How to Use It

You want to install a surveillance camera or Wi-Fi access point on the ceiling, but there is no power outlet nearby. A "PoE injector" is what helps you in such situations. It might sound difficult just by the name, but once you understand how it works, it is surprisingly simple.

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In short, a PoE injector is

PoE (Power over Ethernet) is a technology that performs both data communication and power supply simultaneously via a single LAN cable.

A PoE injector is a device that uses this mechanism to supply power to standard network equipment that does not support PoE.

If you want to install surveillance cameras, Wi-Fi access points, IP phones, etc., in places where it is difficult to install new power outlets, such as ceilings or outdoors, using a PoE injector allows you to complete the installation with just a single LAN cable.

How a PoE injector works

PoE injectors operate in compliance with PoE standards (IEEE 802.3af, 802.3at, 802.3bt).

They perform a confirmation exchange called a 'handshake' between the power-sending and power-receiving devices, and the mechanism is designed not to supply power if the receiving device does not respond correctly.

This prevents the risk of accidentally damaging incompatible devices.

The voltage during power supply is generally 44 to 57 volts DC, and the amount of power that can be supplied varies depending on the standard.

• IEEE802.3af: Up to approx. 15.4W

• IEEE802.3at: Up to approx. 30W

• IEEE802.3bt: Up to approx. 60W to 90W (varies by standard/class)

You need to choose a PoE injector with the corresponding standard according to the power consumption of the device you are connecting.

What is the difference between a PoE injector and a PoE switch?

PoE Injector

This is a device that adds PoE power supply functionality to a specific cable by retrofitting it to an existing non-PoE compatible switch or router. It is a convenient option when you want to add PoE power to a small number of devices.

PoE Switch

The switch itself has built-in PoE power supply functionality for multiple ports. It is efficient when operating a large number of PoE devices, such as in offices or facilities where many surveillance cameras or access points are installed. In this magazine, we review the NETGEAR GS752TXUP which supports 640W PoE++.

A practical approach is to use an injector for a few devices, and a PoE switch if you are operating 10 or more PoE devices.

Situations where a PoE injector is useful

• You want to install surveillance cameras in places where it is difficult to secure an outlet, such as ceilings or outdoors.

• You want to add Wi-Fi access points in locations without power.

• You want to consolidate wiring into a single LAN cable to keep things tidy.

• Your existing switch or router is not PoE compatible, and you want to make only specific devices PoE-enabled.

Points to check when introducing

Does the power consumption of the connected device match the PoE standard?

You need to choose a PoE injector with a standard that exceeds the power required by the device. First, check which standard (af, at, or bt) the device supports.

Is the cable category appropriate?

The quality and category of the cable itself are also important for stable PoE power supply. It is recommended to use Cat6 or higher cables for long-distance wiring or high-output power supply.

Temperature and humidity of the installation environment

For outdoor installation, you need to choose a product with waterproof and dustproof performance.

Frequently Asked Questions (FAQ)

Q1. Can I use my existing LAN cable when using a PoE injector?
A. It depends on the supported category and condition of the cable itself. Old or low-quality cables may not be able to provide stable power, so consider replacing them if necessary.

Q2. Will connecting a PoE injector to a non-PoE device damage it?
A. The PoE standard includes a safety mechanism that prevents power from being supplied if the receiving device does not respond correctly. However, since there are exceptions with some non-compliant products, please be sure to check the compatibility status.

Q3. What is the maximum distance for PoE power supply?
A. Similar to general Ethernet standards, about 100 meters is the standard guideline. However, please note that higher power output is more susceptible to voltage drop.

Q4. Are PoE injectors and PoE extenders the same thing?
A. No, they are different. A PoE extender is a relay device used to extend the reach of PoE power supply. A PoE injector is a device used to add PoE functionality to non-PoE compatible equipment and lines.

Q5. Can one injector power multiple PoE devices?
A. Basically, one PoE injector supports one port (one cable). If you want to operate multiple PoE devices, please prepare multiple injectors or consider switching to a PoE switch.

Q6. Are there any rules for where to install a PoE injector?
A. It is common to install it near the switch or router that serves as the power source. Since the range for stable power supply varies depending on the wiring distance to the receiving device and the cable category, it is safer to plan the installation location in advance.

Summary | A device that simplifies wiring for locations without power outlets

A PoE injector is a device that uses a mechanism to perform data communication and power supply simultaneously over a single LAN cable, enabling the installation of equipment in places where it is difficult to secure a power outlet.

If you want to add surveillance cameras, Wi-Fi access points, etc., it is an option worth considering first.

Choosing a PoE standard (af, at, bt) that matches the power consumption of the connected device and checking the cable category accordingly are prerequisites for stable operation.

If you are operating multiple devices on a full scale, please consider switching to a PoE switch.

If it involves a significant investment, we recommend comparing options rather than making an immediate decision. By first saving items to your Amazon cart, you can carefully compare the supported standards and power supply capacities.

▼ Save to cart first to compare and consider carefully

If you are considering operating multiple units, please also see the Ubiquiti UniFi Cloud Gateway Ultra Review.