Re: PoE auto switchover with Cisco 1252 Access Point.
1- yes it is possible to do failover without unlupping the cable of AC adapter. When power on ACS adapter is off, then the faiolver happens.
2- with regards to POE, if your switch supporting enhanced POE?
Powering the Aironet 1250 Series Access Point with Cisco Enhanced PoE
Cisco Enhanced PoE was designed for customers who want to install new PoE-enabled technologies that require greater than 15.4W per port to function at full capability, such as wireless technology based on the IEEE 802.11n standard. Cisco Enhanced PoE provides the full power requirements for dual-radio modules and eliminates the need to run an additional cabling drop or insert a separate power injector. Support for Enhanced PoE is currently available on a variety of Cisco Catalyst® switching platforms. For more information on Enhanced PoE, visit http://www.cisco.com/en/US/prod/switches/epoe.html.