PoE Is an Intrabuilding Standard
PoE is essentially an intrabuilding standard. There are some confusing references in IEEE 802.3at to Environment A and Environment B:
In Section 188.8.131.52, titled “Electrical isolation environments,” and in Section 184.108.40.206.2:
There are two electrical power distribution environments to be considered that require different electrical isolation properties. They are as follows:
• Environment A: When a LAN or LAN segment, with all its associated interconnected equipment, is entirely contained within a single low-voltage power distribution system and within a single building.
• Environment B: When a LAN crosses the boundary between separate power distribution systems or the boundaries of a single building…. ...