Cisco Aironet 3800 Series - Power Requirements

Cisco AP 2800 and AP 3800 easily function with 802.3at powering systems and for advanced features like
module support (AP 3800) Cisco UPoE can be used.
Figure 44: AP 2800 and AP 3800 requires an 802.3at or better PoE source
If an 802.3at or better power source is not available, the following Cisco mid-span injectors may be used.
Figure 45: Low cost 802.3at GbE injector for AP 2800 and AP 3800 (if mGig is not required)
Cisco Aironet Series 2800/3800 Access Point Deployment Guide
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AP 2800 and AP 3800 Powering Options