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UniFi - Powering a US-8 Switch and Connected Devices


Overview


This article provides different options for powering a UniFi Switch 8-port (US-8), and connected 48V and 24V devices.

NOTES & REQUIREMENTS:
This article applies specifically to the US-8 model, but this information can be determined for any device by seeing its Data Sheet or Quick Start Guide, in the Specifications section. These documents will always be found at the bottom of the product page, which can be accessed when navigating from the UBNT Products page. They can also be downloaded from UBNT Downloads. Whenever possible, use the Quick Start Guide that came with your device, since the online documents are kept updated to the most current version of each product. These documents will also be helpful in determining how many devices you can power with one switch. See more about that here: UniFi - Understanding PoE and How UniFi Devices are Powered.

Table of Contents


  1. Introduction
  2. Powering 48V Devices
  3. Powering 24V Devices
  4. 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 (UAP-AC-PRO) 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. 

NOTE: Newer UAP-AC-LITE (date code 1638 onward) can be powered via 802.3af, so they will in fact be powered by US-8. Not sure what your APs date code is? 
 

 


US-8 CANNOT be Powered by 24V PoE, nor can it provide 24V power to any device:

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: Accessories section. 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:


Related Articles


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UniFi - Correct Controller Versions for UniFi Hardware 

UniFi - How to Setup your Cloud Key and UniFi Access Point (for beginners)

UniFi - VLAN Switch Configuration