PoE Switch Sizing Guide for Security Camera Systems
Power over Ethernet (PoE) eliminates the need for separate power supplies at each camera location. But undersized PoE switches are one of the most common causes of camera reliability issues. Here is how to size them correctly.
PoE Standards and Power Delivery:
| Standard | IEEE Spec | Max Power per Port | Common Use | |----------|-----------|-------------------|------------| | PoE | 802.3af | 15.4W (12.95W at device) | Basic fixed cameras | | PoE+ | 802.3at | 30W (25.5W at device) | PTZ cameras, APs, VoIP phones | | PoE++ (Type 3) | 802.3bt | 60W (51W at device) | High-power PTZ, LED lighting | | PoE++ (Type 4) | 802.3bt | 100W (71.3W at device) | Digital signage, thin clients |
Typical Camera Power Consumption:
| Camera Type | Power Draw | PoE Standard Needed | |-------------|-----------|-------------------| | Fixed dome (no IR) | 8-12W | PoE (802.3af) | | Fixed dome (with IR) | 12-18W | PoE (802.3af) or PoE+ | | Fixed bullet (long-range IR) | 15-25W | PoE+ (802.3at) | | PTZ (small) | 25-35W | PoE+ (802.3at) | | PTZ (large/outdoor) | 40-70W | PoE++ (802.3bt) | | Panoramic/multi-sensor | 20-35W | PoE+ (802.3at) | | Thermal camera | 15-25W | PoE+ (802.3at) | | Camera with heater/wiper | 30-60W | PoE++ (802.3bt) |
Sizing Your PoE Budget:
Step 1: List all PoE devices connected to the switch
Include cameras, wireless APs, VoIP phones, access control readers, and any other PoE-powered devices.
Step 2: Calculate total power draw
Sum the maximum power consumption of all connected devices.
Step 3: Add 20% headroom
Never run a PoE switch at 100% budget. Leave 20% for future devices and peak power spikes (IR when it gets dark).
Example Calculation — 24-Camera System: - 16x fixed domes with IR: 16 x 15W = 240W - 4x outdoor bullets with long-range IR: 4 x 25W = 100W - 2x PTZ cameras: 2 x 50W = 100W - 2x panoramic cameras: 2 x 30W = 60W - Total: 500W - Plus 20% headroom: 600W required PoE budget
A 48-port PoE+ switch with 740W budget handles this with room to spare. A 24-port PoE+ switch with 370W budget would NOT be sufficient.
Switch Selection Considerations:
1. **Port count:** Choose a switch with enough ports for current cameras plus 25% growth. A 24-camera system should use a 48-port switch (or two 24-port switches).
2. **Uplink bandwidth:** The switch uplink must handle total camera bandwidth. Each 4MP camera at 15fps generates ~6Mbps. 24 cameras = 144Mbps sustained — a 1Gbps uplink handles this, but a 10Gbps uplink provides headroom for 4K cameras.
3. **Management:** For security cameras, use managed switches with VLAN support. Isolate camera traffic on a dedicated VLAN.
4. **Reliability:** Look for switches with redundant power supplies for critical camera systems.
5. **Environmental:** For outdoor or harsh environments, use industrial-rated switches with extended temperature range and DIN rail mounting.
Common Mistakes:
- Using a PoE switch as PoE budget is less than total device draw (cameras randomly restart) - Mixing cameras and workstations on the same switch without VLANs - Using unmanaged switches (no QoS, no VLANs, no monitoring) - Long cable runs exceeding 100m (PoE voltage drop causes camera power issues) - Not accounting for IR LED power draw at night (cameras draw more power in the dark)
Our Recommended Switches for Camera Systems:
- 8-16 cameras: Cisco CBS350-24P or Ubiquiti USW-Pro-24-PoE - 16-32 cameras: Cisco CBS350-48P or Meraki MS130-48P - 32-64 cameras: Cisco Catalyst 9200-48P or Aruba CX 6100-48G-PoE4
Summit DNC designs and deploys PoE-powered security camera systems with properly sized switching infrastructure. Contact us for a free system design consultation.
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