How to Power a Ubiquiti Access Point Using a PoE Injector

Ubiquiti access points are one of the most common reasons people buy a PoE injector in the UK. The AP arrives, there’s no power supply in the box, and there’s no PoE switch to hand. This is exactly what a PoE injector is for. Whether you’re adding a single UniFi AP to an existing network or deploying a handful across a small office, understanding which injector you need and how to connect it correctly will save you time and avoid damaging your hardware.

What PoE Standard Does a Ubiquiti Access Point Use?

This is the most important question before you buy anything. Ubiquiti’s access point range is not uniform — different models use different PoE standards, and the older hardware in particular has some important caveats around passive PoE.

Always verify against the official Ubiquiti data sheet for the specific model you have. Power requirements can differ between hardware revisions, and third-party listings are not always accurate. For a hands-on look at what the UAP-AC-Pro delivers in a real-world deployment, see our UAP-AC-Pro review.

What PoE Injector Do You Need for a Ubiquiti AP?

Match the injector to the PoE standard the AP requires. The most common choices for current UniFi hardware:

For 802.3af devices (U6-Lite, U6-LR, UAP-AC-Lite): Any 802.3af-compliant active PoE injector will work. Ubiquiti’s own U-POE-af is designed specifically for this use case and is what Ubiquiti recommends for its 802.3af access points. It delivers 15.4W and negotiates correctly with all 802.3af devices.

For 802.3at devices (U6-Pro, UAP-AC-Pro, UAP-AC-HD): Use an 802.3at injector. Ubiquiti makes the U-POE-at, which delivers up to 30W at the PSE. A standard 802.3af injector will not deliver enough power to an 802.3at device under load — the device may boot but perform poorly or reset under traffic.

For 802.3bt devices (U6-Enterprise): You need an 802.3bt injector or, more practically, an 802.3bt-capable PoE switch. Standalone 802.3bt injectors are available but less common and more expensive. At this power requirement, a PoE switch is usually the better investment.

Third-party active PoE injectors from TP-Link, Netgear, and similar brands work correctly with Ubiquiti APs provided they meet the IEEE standard and wattage requirements. The injector doesn’t need to be a Ubiquiti product — it just needs to be actively negotiating and delivering the right power class. Budget for a reputable brand rather than the cheapest unbranded option; cheap injectors sometimes have inaccurate power class signalling.

Step-by-Step: Connecting a Ubiquiti AP via PoE Injector

1. Run your Ethernet cable to the AP mounting location. Use Cat5e minimum; Cat6 is preferable for future-proofing. Terminate both ends with RJ45 connectors or use a pre-made patch cable from the injector location if the run is short enough.
2. Position the injector near the switch. The injector should sit close to your existing network switch, not at the AP end. Power to the injector comes from a standard mains socket, so position it where a mains outlet is accessible — typically in the comms cupboard or wherever the switch lives.
3. Connect the injector’s uplink (data in) port to your switch. This port is usually labelled “LAN”, “Data In”, or “Uplink”. Use a standard patch cable between this port and any available port on your switch.
4. Connect the injector’s PoE output port to the cable running to the AP. This port is usually labelled “PoE”, “Data + Power”, or “PoE Out”. The cable from this port carries both data and power to the access point.
5. Plug the injector into mains power. The injector will power on and begin the PoE detection and negotiation process on the output port.
6. Wait for the AP to boot. UniFi access points take 60–90 seconds to complete their boot sequence. Watch the LED indicator on the AP:
   • Solid white — booted, adopted, and operating normally
   • Pulsing white — booted but not yet adopted in UniFi Network
   • Flashing white — firmware upgrade in progress (do not remove power)
   • Solid blue — access point is in the process of being adopted
   • No light — no power or hardware fault
7. Adopt the AP in UniFi Network. If this is a new AP, log into your UniFi Network console (self-hosted or UniFi Site Manager) and adopt the device. It will appear in the Pending Devices list if the AP is on the same layer-2 network as the controller.

Ubiquiti’s 24V Passive PoE Warning

This is worth stating explicitly because it still catches people out. Older Ubiquiti access points — particularly early UAP and UAP-AC models from 2014–2018 — shipped with 24V passive PoE injectors. These are not compatible with standard 802.3af switches or injectors.

If you have old Ubiquiti gear in a cupboard or inherited an installation with legacy UniFi hardware, check the injector label before assuming it is a standard active PoE injector. Ubiquiti’s 24V passive injectors are usually labelled clearly with the voltage and often carry a warning not to use them with non-Ubiquiti equipment.

Connecting a 24V passive injector to a device that expects 802.3af active PoE, or vice versa, can cause equipment damage. For the full explanation of why this matters and how to identify which type you have, see our guide on active vs passive PoE.

Current UniFi 6 hardware has moved entirely to standard 802.3af/at active PoE. If you are purchasing new equipment, this issue does not apply. If you’re working with older gear, verify before you connect.

Cable Length and PoE

PoE operates within the same physical limits as standard Ethernet — 100 metres maximum per cable segment, measured from the PSE (injector or switch port) to the PD (access point). Beyond 100m, you will see both data and power degradation.

For most UK installs, staying within 100m is straightforward. Where it becomes relevant is in larger properties — long corridor runs, outbuildings, or multi-floor office layouts. If you need to exceed 100m, you’ll need a PoE extender or a secondary switch with an uplink, not a longer cable.

Cable category matters for power delivery efficiency:

• Cat5e: Minimum acceptable for PoE. Adequate for 802.3af and 802.3at at normal cable lengths.
• Cat6: Lower resistance, better power delivery efficiency over longer runs. Recommended for new installations.
• Cat6A: Required for 802.3bt (PoE++) at full power over longer cable runs.

For outdoor installations — mounting an AP on an external wall, in a car park, or on a roof — use shielded outdoor-rated cable (S/FTP or similar) designed for UV exposure and temperature variation. In buried runs, use direct burial rated cable. Standard indoor Cat5e or Cat6 will degrade quickly when exposed to the elements.

Troubleshooting: Ubiquiti AP Not Powering Up

If the AP LED shows no light after connecting, work through these checks before assuming the AP or injector is faulty:

• Check you are using the correct port on the injector. Many injectors have two RJ45 ports — one for data in (from switch) and one for PoE out (to device). Plugging the AP into the data-in port means it receives no power. The ports are usually labelled, but check the injector’s documentation if the labelling is unclear.
• Confirm the injector has mains power. Check the injector’s power LED, if it has one, or verify the plug socket is live.
• Test cable continuity. Use a cable tester to verify all four pairs are connected correctly end-to-end. PoE uses all four pairs in 802.3at and above, so a partial cable fault may power the device but cause data issues, or prevent power negotiation entirely.
• Try a short patch cable directly from injector to AP. This eliminates the long cable run as a variable. If the AP powers up on a short cable but not the long run, you have a cable fault or length/quality issue.
• Verify the injector’s power class matches the AP’s requirement. An 802.3af injector connected to an 802.3at-only device may not deliver enough power. Check both the injector specification and the AP data sheet.

For a more detailed troubleshooting walkthrough covering injector faults, cable issues, and switch port configuration, see our full guide on PoE injector not working — how to fix it.

What If You Have Multiple Ubiquiti APs?

A single PoE injector per AP is entirely manageable for one or two access points. At three or more, individual injectors start to become unwieldy — multiple mains sockets consumed, multiple cable management issues, and no central point for power monitoring or management.

At this scale, a PoE switch is the cleaner solution. A managed PoE switch gives you per-port power monitoring (useful for verifying each AP is drawing the expected wattage), the ability to remotely power-cycle an AP without physical access to the injector, and a single point of management for all your cabling.

Ubiquiti’s own UniFi switches integrate natively with UniFi Network and provide per-port PoE control directly from the controller interface. Third-party managed PoE switches from TP-Link, Netgear, or Cisco will also work, though without native UniFi integration. For a full comparison of injectors versus switches and when to make the switch, see our guide on PoE injector vs PoE switch.

Getting It Right First Time

Powering a Ubiquiti access point via a PoE injector is a ten-minute job when you have the right components. The most common mistakes are buying an injector with the wrong power class for the AP model, connecting cables to the wrong injector port, or using old passive PoE hardware with newer 802.3af/at devices.

Check the AP’s data sheet, match the injector standard and wattage, run the cable correctly, and the AP will power up cleanly. If it doesn’t, the troubleshooting steps above will identify the fault before you assume the hardware is defective.

Related: UniFi home network guide