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Power over Ethernet (PoE) is a technology that enables Ethernet cables to carry electrical power along with data, simplifying the installation of devices such as IP cameras, VoIP phones, and wireless access points. Understanding the pinouts for PoE is essential for correctly wiring and troubleshooting network devices. This guide will cover the various PoE pinouts required for different standards.
Understanding PoE Pinouts
In Ethernet cabling, data is transmitted over twisted pairs of wires. PoE takes advantage of these pairs to deliver power. Depending on the PoE standard being used, power may be delivered over the same pairs as data or separate pairs.
Ethernet Cable and PoE Basics
- Ethernet Cable Types: Typically, Cat5e, Cat6, or higher cables are used for PoE.
- Twisted Pairs: Ethernet cables contain 4 pairs (8 wires) labeled 1 through 8.
- RJ45 Connectors: These connectors are used to terminate Ethernet cables and connect them to network devices.
PoE Modes
There are two primary modes used in PoE standards to deliver power:
- Mode A (Alternative A): Power is delivered on the same wires used for data transmission.
- Mode B (Alternative B): Power is delivered on the spare pairs (unused pairs in data transmission).
PoE Pinouts by Standard
1. IEEE 802.3af (PoE) and IEEE 802.3at (PoE+)
These standards support both Mode A and Mode B, allowing flexibility in how power is delivered.
| Pin Number | Pair | Mode A (Data & Power) | Mode B (Spare Pairs) |
|---|---|---|---|
| 1 | Pair 1 | Positive (+) | Not Used |
| 2 | Pair 1 | Positive (+) | Not Used |
| 3 | Pair 2 | Negative (-) | Not Used |
| 6 | Pair 2 | Negative (-) | Not Used |
| 4 | Pair 3 | Not Used | Positive (+) |
| 5 | Pair 3 | Not Used | Positive (+) |
| 7 | Pair 4 | Not Used | Negative (-) |
| 8 | Pair 4 | Not Used | Negative (-) |
- Mode A: Power is sent over the data pairs 1/2 and 3/6.
- Mode B: Power is sent over the spare pairs 4/5 and 7/8.
2. IEEE 802.3bt Type 3 (4PPoE) and Type 4 (PoE++)
These advanced standards utilize all four pairs to deliver higher power levels.
| Pin Number | Pair | Type 3 (PoE++ Mode A) | Type 3 (PoE++ Mode B) | Type 4 (PoE++ Mode A & B) |
|---|---|---|---|---|
| 1 | Pair 1 | Positive (+) | Positive (+) | Positive (+) |
| 2 | Pair 1 | Positive (+) | Positive (+) | Positive (+) |
| 3 | Pair 2 | Negative (-) | Negative (-) | Negative (-) |
| 6 | Pair 2 | Negative (-) | Negative (-) | Negative (-) |
| 4 | Pair 3 | Positive (+) | Negative (-) | Positive (+) |
| 5 | Pair 3 | Positive (+) | Negative (-) | Positive (+) |
| 7 | Pair 4 | Negative (-) | Positive (+) | Negative (-) |
| 8 | Pair 4 | Negative (-) | Positive (+) | Negative (-) |
- Type 3 (PoE++): Uses all four pairs, either Mode A or Mode B, to deliver up to 60 watts.
- Type 4 (PoE++ or 4PPoE): Uses all four pairs simultaneously to deliver up to 100 watts, with more balanced power distribution.
Practical Applications
Example 1: VoIP Phone Using PoE (IEEE 802.3af)
- Typical Power Requirement: 5-10 watts
- Pinout: Usually follows Mode A
- Pin Configuration:
- Pins 1/2: Positive (+)
- Pins 3/6: Negative (-)
Example 2: IP Camera Using PoE+ (IEEE 802.3at)
- Typical Power Requirement: 15-25 watts
- Pinout: May use either Mode A or Mode B depending on the device
- Pin Configuration:
- Mode A (Common):
- Pins 1/2: Positive (+)
- Pins 3/6: Negative (-)
- Mode B (Alternative):
- Pins 4/5: Positive (+)
- Pins 7/8: Negative (-)
Example 3: High-Power Wireless Access Point Using PoE++ (IEEE 802.3bt Type 4)
- Typical Power Requirement: 30-60 watts
- Pinout: Utilizes all four pairs
- Pin Configuration:
- Pins 1/2: Positive (+)
- Pins 3/6: Negative (-)
- Pins 4/5: Positive (+)
- Pins 7/8: Negative (-)
Conclusion
Understanding PoE pinouts is crucial for correctly implementing and troubleshooting PoE-powered networks. Whether you’re dealing with simple devices like VoIP phones or high-powered equipment like modern wireless access points, knowing the pin configurations can ensure smooth operations and prevent connectivity issues. This guide should serve as a quick reference for setting up and managing PoE devices across various standards.