Power over Ethernet (PoE) sends both data and electricity down one network cable, so you can put an access point, camera or phone where there is no power socket. But "PoE" covers several standards, and mixing them up can mean a device that will not power on — or worse.
The standards
- 802.3af (PoE): up to ~15.4 W at the port. Fine for most access points and IP phones.
- 802.3at (PoE+): up to ~30 W. For dual-band APs, PTZ cameras and heavier devices.
- 802.3bt (PoE++): up to ~60 W (Type 3) or ~100 W (Type 4). For high-power APs, displays and more.
Passive PoE
Many MikroTik devices use passive PoE, which simply puts a fixed voltage (often 24 V or 48 V) on the cable with no negotiation. It is simple and inexpensive, but you must match the voltage the device expects — do not plug a passive-PoE injector into a device that only speaks 802.3af/at unless you are sure it is compatible.
Practical tips
- Check the voltage and wattage a device needs before choosing an injector or switch.
- Budget the total PoE power of a switch, not just per-port — a switch may not deliver full power on every port at once.
- Cable length and quality matter; long, thin runs lose power.
If you tell us what you are powering and how far the cable runs, we will match the right injector or PoE switch.