For the X460-G2-48p (2nd Gen X460 with POE capabilities), we have a choice between the following:
1) Summit 1100W AC PSU: Choose a PSU with a matching airflow to the switch: either part# 10941 (FB --> Front-to-Back airflow) or part# 10942 (BF --> Back-to-Front airflow).
2) Summit 715W AC PSU: Choose a PSU with a matching airflow to the switch: either part# 10951 (FB --> Front-to-Back airflow) or part# 10952 (BF --> Back-to-Front airflow).
The Summit 1100W AC PSU can provide 850 watts of POE-plus power budget per one power supply and the Summit 715W AC PSU can provide 500 watts of POE-plus power budget per one power supply. If a higher power budget is required, two of the same type of power supply (two Summit 1100W AC PSUs or two Summit 715W AC PSUs can be installed in either the X460-G2-48p-10GE4 or X460-G2-48p-GE4 switch, based on the model you have.
You can click on the link below to access the X460-G2 Data Sheet on our web site for more information:http://learn.extremenetworks.com/rs/extreme/images/Summit-X460-G2-DS.pdf
Based on your specific POE power budget requirements, please refer to page 7 in the X460-G2 Data Sheet to get more information regarding the POE power budget allocation which will help you determine which PSU(s) would better suit your current and future POE power needs.