What is PoE?
Power over Ethernet (PoE) delivers both data and electrical power over a single Ethernet cable, eliminating the need for separate power supplies for devices like IP cameras, access points, and VoIP phones.
PoE Standards
| Standard | Power per Port | Total Budget | Use Case |
|---|---|---|---|
| 802.3af (PoE) | 15.4W | 370W (24-port) | IP phones, basic cameras |
| 802.3at (PoE+) | 30W | 740W (24-port) | PTZ cameras, WiFi 6 APs |
| 802.3bt (PoE++) | 60W/90W | 1440W+ | High-power PTZ, LED lighting |
How to Calculate Power Budget
- List all devices and their power consumption
- Add 20% headroom for peak draw and cable loss
- Check switch total budget — must exceed sum of all devices
Example: 8 cameras × 15W = 120W → Choose switch with 150W+ budget
Port Count & Speed
- 8-port: Small offices, retail stores
- 16-port: Medium businesses, small CCTV systems
- 24-port: Large offices, enterprise WiFi
- 48-port: Data centers, large deployments
Always include 2-4 extra ports for expansion.
Managed vs Unmanaged PoE Switches
- Unmanaged: Plug-and-play, no configuration — cheapest option
- Managed L2: VLANs, QoS, port monitoring — recommended for most deployments
- Managed L3: Routing, ACLs, advanced security — enterprise/ISP grade
Key Features to Look For
- Auto-sensing PoE: Only delivers power to PoE devices (protects non-PoE equipment)
- Per-port power management: Monitor and limit power per port
- Surge protection: Essential for outdoor camera installations
- Extended temperature: -40°C to +75°C for industrial/harsh environments
BHL Networks PoE Switch Range
From 4-port unmanaged to 48-port managed L3 switches with 740W+ PoE budgets. All switches support 802.3af/at/bt standards with intelligent power management and surge protection.