2
4 Surge Protection
Network cables used outdoors must be buried underground or routed through steel pipes to protect the switches
from lightening. Do not route network cables overhead.
If the network ports on the switches are connected to devices on a street pole, no surge protector needs to be
installed. If the network ports are connected to devices on a tower, a network port surge protector must be
installed.
To protect network ports from lightning, use 8-line surge protectors or Huawei certified 4-line surge protectors.
When installing a network port surge protector, connect the IN ports to network devices and connect the OUT
ports to network ports of the switches.
If fiber reinforcing ribs are used, ensure that they are properly grounded to protect the switches from lightning.
Surge Protection Requirements for Network Ports
AC switch:
In all installation scenarios, the switches, cabinets, independent power modules, and surge protectors must be
separately grounded.
When installing the S5720I-SI series switches in outdoor cabinets, ensure that the following requirements are met:
The 20 kA surge protector and S5720I-SI switch can be decoupled using 5-10 m power cables or decoupling inductors.
Using 5-10 m power cables for decoupling
Surge Protection Requirements for Power Ports
If the 220 V mains supply is used, install a 20 kA surge protector between the power port of the switch and the mains.
If power is supplied by an isolated inverter near the outdoor cabinet, no surge protector needs to be installed between the
power port of the switch and the inverter.
DC switch: An isolated power supply must be used and placed in the same outdoor cabinet as the switch. Surge
protection is required for the power input of the outdoor cabinet. The surge protector, power supply, and switch
must be equipotential. The outdoor cabinet must be properly grounded and the grounding impedance must be
less than or equal to 10 ohms. If a DC switch is connected to the PAC-260WA-E power module that is powered
by the 220 V mains, install a 20 kA surge protector between the power input port of the PAC-260WA-E and the
mains.
20 kA surge
protector
220V AC mains
The ground cable should not exceed 1 m in length
PE
S5720I-SI Switch
Use 5-10 m power cables as the
L and N wires for decoupling.
L
N
PE
Using decoupling inductors for decoupling
20 kA surge
protector
220V AC mains
The ground cable should not exceed 1 m in length
PE
S5720I-SI Switch
Use a surge protection decoupling inductor
with an inductance of 5-10 µH on
both the L and N wires for decoupling.
L
N
PE
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