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80 C120-H007-05EN
CHAPTER 6 Power Supply Facilities
6.4.3 Grounding LAN devices
Grounding LAN devices which share the same signal ground to the same grounding
system and those which have different signal ground to different grounding systems.
The method for grounding LAN devices, details of the separation of the LAN
transmission line signal ground from the connected devices, and typical modes of
LAN connection and grounding are described below.
(1) Grounding LAN devices
The signal ground of each device signal line is separated at the point of connection
with the LAN transmission line for both optical and metal cables.
A coaxial cable transmission line must be grounded at one point per segment.
LAN devices may be grounded to different grounding systems individually or in
groups.
A group of devices connected to the same transceiver must be grounded to the same
grounding system.
(2) Separation of the LAN transmission line signal ground from the
connected devices
The LAN transmission line signal ground is separated from the ground of the
connected devices. Table 6.7 details the separation of the signal ground.
(3) Typical modes of LAN connection and grounding
Typical LAN connections and grounding are described below with regard to
100Base-T.
Figure 6.5 shows a typical 100Base-T connection. The transmission route of a twisted
pair cable is not to be grounded.
Table 6.7 Details of the separation of the LAN transmission line signal ground (SG)
Transmission line Cable type Details
Fibre Optical fibre Separation by opto-electrical and
electrical-opto-signal converters
10Gigabit Ether Optical fibre
Gigabit Ether Optical fibre
FDDI Optical fibre
100BASE-T Paired Separation by transceiver's signal
transformer
Gigabit Ether Optical fibre