This guide provides comprehensive explanations of the elements in selecting and using Power Over Ethernet with IP cameras, covering:
- PoE vs Low Voltage
- When to Use PoE, When Not
- PSEs vs PDs
- PoE Classes
- 802.3af vs 802.3at vs 802.3bt
- Nonstandard PoE Implementations
- Passive PoE
- Spare Pairs
- Distance Limitations
- PoE Extenders
- Power Consumption vs Specification
- Calculating Power Budget
- PoE via Switch, MidSpan or NVR
- The Top 5 PoE Misunderstanding
PoE vs Low Voltage
All cameras need electrical power to operate.
'Power over Ethernet' (PoE) uses a single cable to connect a camera to both the data network and a power supply. In most cases, powering cameras before the advent of PoE meant using low voltage power using separate power supplies and dedicated power wiring. PoE eliminates the second cable / supply.
Using this single cable with power built into switches saves cost compared to low voltage power supplies, typically ~$10-30 per camera. See: PoE vs Low Voltage Power Supplies Cost Compared.
PoE Almost Always Used
PoE is supported and used, in practice, in almost all professional IP cameras and installations.
Exceptions To PoE Use
There are some exceptions where PoE is not used with IP cameras: