What Is Power over Ethernet (PoE)?
How One Cable Can Deliver Both Power and Data
Imagine installing a security camera on the corner of a warehouse.
Years ago, you needed two separate cables:
- One cable to carry video or network data
- One cable to supply electrical power
That meant more labor, more materials, more electricians, and more installation costs.
Today, thanks to Power over Ethernet (PoE), a single Ethernet cable can provide both data and electrical power to many devices.
It’s one of the biggest innovations in the low-voltage industry, helping businesses reduce installation costs while making networks cleaner, simpler, and easier to expand.
What Is Power over Ethernet?
Power over Ethernet, commonly called PoE, is a technology that allows standard Ethernet cable to carry both:
- Data
- Electrical power
Instead of installing a separate electrical outlet near every device, power is delivered directly through the same network cable that’s already carrying information.
That means one cable can do the work of two.
How Does PoE Work?
Every PoE system has two main components:
Power Sourcing Equipment (PSE)
This is the device that provides power.
Examples include:
- PoE network switches
- PoE injectors
Powered Device (PD)
This is the device receiving both power and data.
Examples include:
- IP security cameras
- Wireless access points
- VoIP telephones
- Video intercoms
- Door controllers
- Digital signage
- Building sensors
- Network speakers
When a compatible device is connected, the switch automatically detects that it supports PoE and safely supplies the appropriate amount of power.
Why Is PoE So Popular?
Power over Ethernet has transformed modern building technology because it offers several major advantages.
One Cable Instead of Two
Only a single Ethernet cable needs to be installed.
This reduces:
- Labor
- Material costs
- Conduit requirements
- Wall penetrations
- Installation time
Easier Expansion
Need another camera?
Simply run one network cable back to the switch.
No additional electrical outlet is usually required.
Cleaner Installations
Equipment rooms become easier to organize because power and networking are managed together.
Instead of dozens of power adapters scattered throughout a building, devices receive centralized power from the network.
Centralized Backup Power
One of PoE’s biggest advantages is that all connected devices can remain operational during a power outage when the network switch is connected to an uninterruptible power supply (UPS).
Instead of installing battery backups at every camera or phone, one UPS can keep an entire network of PoE devices running.
Common Devices That Use PoE
Today, PoE powers far more than security cameras.
Some of the most common devices include:
Security Cameras
Perhaps the most recognizable PoE application.
One Cat6 cable provides:
- Power
- Video
- Network communication
Wireless Access Points
Ceiling-mounted Wi-Fi access points are ideal candidates for PoE because electrical outlets rarely exist where they’re needed.
VoIP Phones
Office telephones commonly receive both network connectivity and power through one Ethernet cable.
Access Control
Many access control systems use PoE for:
- Door controllers
- Readers
- Intercom stations
- Network-connected devices
Some door hardware still requires separate power depending on the lock type and system design.
Video Intercoms
Modern video door stations often operate entirely from PoE, simplifying installation while maintaining full network connectivity.
Digital Signage
Many interactive displays and information kiosks rely on PoE for streamlined deployment.
Building Automation
Smart buildings use PoE to power sensors, lighting controllers, environmental monitoring devices, and other connected equipment.
PoE Standards Explained
Not all PoE systems deliver the same amount of power.
Over time, newer standards have increased the amount of power available for more demanding devices.
| Standard | Common Name | Maximum Power (Port) | Typical Devices |
|---|---|---|---|
| IEEE 802.3af | PoE | 15.4 W | IP phones, small cameras |
| IEEE 802.3at | PoE+ | 30 W | PTZ cameras, Wi-Fi access points |
| IEEE 802.3bt | PoE++ | Up to 60–90 W* | Displays, advanced cameras, lighting, specialty devices |
*The exact power available to the connected device depends on the PoE type, cable length, and equipment.
For many commercial installations today, PoE+ provides more than enough power for the majority of connected devices.
Does Cable Type Matter?
Absolutely.
While Cat5e can support PoE, many new commercial installations use Cat6 or Cat6A because they provide additional performance headroom and are well suited for today’s higher-bandwidth and higher-power applications.
Proper installation also matters.
Poor terminations, damaged cable, or excessive cable bundling can affect both data performance and power delivery.
PoE vs. PoE+
People often ask if PoE and PoE+ are the same thing.
Not quite.
Think of it like fuel pumps.
Both deliver fuel—but one can supply more.
PoE+ provides additional power for devices that require more energy, such as larger wireless access points, pan-tilt-zoom (PTZ) security cameras, and other advanced equipment.
PoE++ extends that capability even further for specialized applications.
Common Myths
“PoE is dangerous.”
PoE operates at relatively low voltage and includes safeguards that verify device compatibility before power is applied. Like any electrical system, it should still be installed according to manufacturer instructions and applicable codes.
“Every Ethernet cable provides PoE.”
No.
Both the network equipment and the connected device must support PoE, or a compatible PoE injector must be used.
“PoE slows down the network.”
No.
Power and data travel together without reducing network speed. Network performance depends on the capabilities of the equipment and cabling, not on the presence of PoE.
Pro Tip from Planet Low Voltage
One of the most common service calls we see involves someone plugging a PoE device into a standard, non-PoE switch and wondering why it won’t power on.
Before replacing a camera, phone, or access point, always verify:
- Is the switch actually providing PoE?
- Is PoE enabled on that port?
- Does the device require PoE, PoE+, or PoE++?
- Is the Ethernet cable terminated correctly?
- Is the total cable length within specifications?
A two-minute check can often save hours of troubleshooting.
Frequently Asked Questions
Can PoE damage non-PoE devices?
No. Standard PoE equipment performs a detection process before supplying power, so compatible equipment will not send power to devices that don’t request it.
How far can PoE travel?
PoE follows standard Ethernet distance limits, with a maximum channel length of approximately 328 feet (100 meters) under normal conditions.
Can PoE power electric door locks?
Sometimes. Some low-power locking devices can be powered through PoE systems, while many electric strikes and maglocks require separate power supplies. The correct solution depends on the hardware and system design.
Do I still need an electrician?
Often, yes. While PoE reduces the need for electrical outlets at individual devices, network switches, UPS systems, and other equipment still require properly installed electrical power.
Planet Low Voltage Recommendation
Whenever practical, we recommend using PoE-capable network switches for new commercial installations.
They simplify wiring, reduce installation costs, improve system reliability, and make future expansion much easier. Combined with quality structured cabling and a properly sized UPS, PoE creates a clean, scalable infrastructure that supports today’s technology while preparing your building for tomorrow’s.
Continue Learning
- What Is Low Voltage?
- What Is Structured Cabling?
- Cat5e vs. Cat6 vs. Cat6A
- Understanding Network Switches
- What Is a Patch Panel?
- Fiber Optic Cable Explained
- Understanding Wi-Fi Networks
- How to Build a Professional Network Rack