Power over Ethernet (PoE) Types, Classes, and RP Categories Explained

Power over Ethernet (PoE) is a technology that allows both data and power to be transmitted through an Ethernet cable to devices such as IP cameras, wireless access points, phones, and other networked devices. To make sense of PoE, it’s helpful to understand the different PoE Types, PoE Classes, and RP (Required Power) Categories. Here’s an in-depth explanation of each.

1. PoE Types (Standards)

There are several PoE standards that define the maximum power delivered over Ethernet cables. Each standard has its own characteristics in terms of wattage, supported devices, and voltage. These standards are governed by the IEEE (Institute of Electrical and Electronics Engineers).

a. IEEE 802.3af (PoE)

• Maximum Power Delivered: 15.4 watts (to the device)
• Power Supply Voltage: 48V DC
• Usage: This is the original PoE standard. It can deliver enough power for devices with relatively low power requirements, such as IP phones and small wireless access points.
• Typical Use: Low-power devices that don’t require much power to function.

b. IEEE 802.3at (PoE+)

• Maximum Power Delivered: 25.5 watts (to the device)
• Power Supply Voltage: 48V DC
• Usage: This is an enhanced version of PoE, providing more power for devices with higher power needs.
• Typical Use: Devices like PTZ (Pan-Tilt-Zoom) cameras, higher-end wireless access points, and some more power-demanding IP phones.

c. IEEE 802.3bt (PoE++ or 4PPoE)

• Type 3 (PoE++ or 4PPoE Type 3)

Maximum Power Delivered: 60 watts (to the device)

Power Supply Voltage: 48V DC

Usage: Supports high-power devices like some types of IP cameras, LED lighting systems, and advanced access points.

• Type 4 (PoE++ or 4PPoE Type 4)

Maximum Power Delivered: 100 watts (to the device)

Power Supply Voltage: 48V DC

Usage: Type 4 PoE is used for high-power devices, such as digital signage, large pan-tilt cameras, and devices that require more than just basic networking power.

2. PoE Classes

PoE Classes define how much power a device requires from a PoE source, and they help optimize power delivery to avoid overloading.

There are 4 PoE classes defined by the IEEE:

• Class 0: < 15.4W (IEEE 802.3af)
  This class includes devices that require less than the 15.4W power limit of PoE. Most PoE devices fall into this class, including basic IP phones and small wireless access points.
• Class 1: < 4W
  This class applies to devices with minimal power needs, such as basic sensors or simple network devices like cameras that require minimal power to operate.
• Class 2: < 7W
  This class can support devices that require more power than Class 1 but still relatively low power, such as smaller wireless access points or entry-level cameras.
• Class 3: < 15W (PoE+)
  Devices in this class require more power than Class 2 but less than the 25.5W maximum provided by PoE+. It can support medium-power devices, such as higher-end phones or security cameras with more features.
• Class 4: < 25.5W (PoE+)
  Devices that need up to the maximum allowed by PoE+ (25.5W) are in this class. Common uses include wireless access points and advanced security cameras.
• Class 5, 6, and 7: < 60W (PoE++)
  These classes exist for higher-power devices and are particularly relevant for PoE++ (IEEE 802.3bt Type 3) systems. Devices in these categories typically need more than 30W of power but can fit within the range for Type 3 PoE++ (up to 60W).

3. RP (Required Power) Categories

The RP (Required Power) category refers to the total power budget that needs to be delivered by the PoE source. The RP category is essential for both the power source equipment (PSE) and the powered device (PD) to ensure that the correct amount of power is available.

• PSE (Power Sourcing Equipment): The device that supplies power, typically a PoE switch or injector.
• PD (Powered Device): The device that receives power, such as an IP camera, wireless access point, or phone.

The RP category helps ensure that the power available from the PSE matches the power requirements of the PD. For example:

• RP Category 1 (Low Power): Devices that fall under the PoE standard (15.4W).
• RP Category 2 (Medium Power): Devices that require PoE+ (up to 25.5W).
• RP Category 3 (High Power): Devices that require PoE++ (up to 60W or 100W, depending on Type 3 or Type 4).

This ensures that the network infrastructure delivers sufficient power to devices based on their category, helping to avoid power supply issues and ensuring optimal operation.

Summary of PoE Standards and Classes:

In Conclusion: The PoE (Power over Ethernet) types (standards) define the maximum power that can be delivered. PoE classes categorize devices by their power needs, helping optimize the allocation of power. RP categories ensure the power supply can meet the requirements of the powered device, preventing under-powering or overloading.

By selecting Syston Cable Technology’s Extended PoE Cable solutions, you’re future-proofing your network infrastructure to support long-distance, bandwidth-intensive applications, while upholding the high standards of reliability and performance essential in today’s fast-moving business environment.

If you have any further questions, don’t hesitate to reach out! Our experts are here to assist you in finding the ideal cable solution. Visit our website, check out our Facebook or contact us directly for more information.