Poe Deployment Environments A And B - Transition Networks SM8TAT2SA-DC Install Manual

Transition Networks SM8TAT2SA-DC Install Guide

PoE Deployment Environments A and B

IEEE802.3at-2009 defines two deployment environments in section 33.4.1:
Environment A: when both PSE and PD are located indoors, inside the same building. In this environment, there
has to be electrical isolation between the PoE circuitry and the data circuitry inside a PSE. Multi-port PSE's can
all share the same ground isolation. Environment A is therefore an indoor PSE – indoor PD environment (a.k.a.
indoor/indoor).
Environment B: when the PSE and PD are not located in the same building. In this environment there needs to
be electrical isolation between PoE and data, as well as between every port in a multi-port PSE. This isolation
between ports requirement de facto determines a completely separate power supply per port, which makes
multi-port PSE's for outdoor PD deployment impractical. Environment B is therefore an indoor PSE - outdoor PD
(a.k.a. indoor/outdoor) or outdoor PSE-outdoor PD (a.k.a. outdoor/outdoor) environment.
This means only single-port PSE's should normally be used when PD's are deployed outdoors. In summary, the
PD-PSE environment is one of these three combinations:
1. PoE Source is indoor, PD is indoor (Env. A)
2. PoE Source is indoor, PD is outdoor (Env. B)
3. PoE Source is outdoor, PD is outdoor (Env. B)
Option 3 is the most challenging environment since both the PD and PSE are installed outdoors. Caution: The
switch is an indoor device. If it is to be used with outdoor devices such as outdoor IP cameras or outdoor Wi-Fi
APs, then you are strongly suggested to install a surge protector or surge suppressor in order to protect the
switch. The switch is compliant with 802.3at in Environment A when using an isolated power supply. For 802.3at
Environment B applications, i.e. building to building, copper to copper endpoint connections: 1) use an Ethernet
network isolator module (PoE disabled), or 2) use mid-span injector(s) such as Transition Networks' MIL-L100i or
L1000i-at, between this switch's PSE port and link partner PD port.
Mode A vs. Mode B
Alternative A, also known as Mode A, uses the data pairs of an Ethernet link to deliver power. Data Pairs include
pins 1,2 and 3,6. PSEs using Mode A supply a positive voltage to pins 1 and 2. Alternative B, also known as Mode
B, uses the spare pairs to deliver power. Spare Pairs include pins 4,5 and 7,8.
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