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UniFi - Powering a US-8 Switch and Connected Devices

Overview


This article discusses options for powering the US-8 Switch and connected devices.

Table of Contents


  1. Introduction
  2. Powering 48V Devices
  3. Powering 24V Devices
  4. Alternative Powering Options with 24V Power Input
  5. Related Articles

Introduction


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The UniFi US-8 switch provides flexible input options and a single PoE output. The switch may be powered by a power cord or POE on port 1, and provides a single POE output on port 8 that is dependent on input power. PoE Out is disabled by default, but can be activated in the UniFi controller.

The following table, found in the US-8 Quick Start Guide, shows passthrough voltage on PoE Out for supported power inputs:

PoE in (Port1) Passthrough PoE Out (Port 8)
802.3at 802.3af
48V Passive 48V Passive
DC Input (Power Adapter) Passthrough PoE Out (Port 8)
48VDC Input (Included) 48V Passive (2-Pair)

Note the difference between 802.3af and 802.3at (commonly called PoE+). 802.3af provides up to 12.95W of continuous power, while 802.3at delivers up to 25.5W.


Powering 48V Devices


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When powered by PoE+, 48V passive POE, or the included 48V Power Adapter, the US-8 will output 48V, powering many UniFi Devices—including the UAP-AC-PRO. Note that the US-8 cannot be used to power devices requiring greater than 12W - such as UAP-AC-EDU. When powered by 802.3af, the switch will run but not provide PoE out.

48V Device Powered by 802.3at PoE Passthrough

48V Devices CANNOT Be Powered By 802.3af PoE Passthrough

48V Device Powered by Included 48VDC Power Adapter


Powering 24V Devices


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24V Power input is not supported on US-8. However, Several UniFi devices—including UAP-AC-LITE and UAP-AC-LR—run on 24V Passive PoE. 

 

US-8 CANNOT be Powered by 24V PoE

In order to power a 24V passive device on POE Out, we recommend using a 48V power input, then connecting a 802.3 gigabit adapter (INS-3AF-I-G or INS-3AF-O-G) to PoE Out to convert 48V PoE Out to 24V. Indoor and outdoor 802.3 gigabit adapters are available on the UBNT Store: https://store.ubnt.com/accessories.html. As with 48V devices, 802.3af PoE will power the switch, but not connected devices.

24V Passive Device Powered by 802.3at PoE Passthrough w/ INS-3AF-I-G

24V Devices CANNOT Be Powered By 802.3af PoE Passthrough with INS-3AF-I-G

24V Passive Device Powered by Included Power Adapter w/ INS-3AF-I-G


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