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R240D
Hardware Installation and Maintenance Guide
5.3.2 Grounding Specifications for an Equipment Room
The grounding resistance of a comprehensive communication building should be less than or
equal to one ohm. The grounding resistance of an ordinary communication office should be
less than five ohms. The grounding resistance in an area where the earth resistance rate is high
should be less than 10 ohms.
5.3.3 Grounding Specifications for Devices
Table 5-17 lists the equipment grounding specifications.
Table 5-17 Equipment Grounding Specifications
No.
1
2
3
4
5
6
5.3.4 Grounding Specifications for Communications Power
Supply
Table 5-18 shows the grounding specifications for communication power supplies.
Issue 03 (2016-01-26)
Description
All communication devices and auxiliary devices (such as mobile base stations,
transmission and switching devices, power supply devices) in the equipment room
should be grounded for protection. Connect all protective ground for various
devices jointly to a general ground bar, and then to the same protective ground bar
in the room together with the protective ground (PGND) of the device.
The PGND of the equipment is shorted to the copper ground bar provided by the
customer. The short-circuiting cable used should be a yellow-green plastic
insulated cable with a copper core and a cross-sectional area greater than 25 sq.
mm (0.039 sq. in.).
There are grounding terminals and grounding lugs at the lower part of the front
door, rear door and side panel of the cabinet, connected to the grounding terminals
of the cabinet framework through connection cables with cross-sectional area of no
less than 1.6 sq. mm (0.002 sq. in.).
Ensure that all metal components of the cabinet conduct well. No insulating
coating should be sprayed on the connection part of the metal components.
Connect the cabinets in the same row by fastening captive screws and gaskets on
the top of the cabinets. Do not spray any coating into a rectangular area measuring
30 mm x 50 mm (1.18 in. x 1.97 in.) around the connection hole for a captive bolt.
Measures to prevent rust and corrosion must be taken for this area. Zinc
electroplating with iridescent yellow chromate conversion coating should be
applied to the gasket and nut to ensure good electrical contact.
When combining cabinets of the same type, short-circuiting cables are required to
connect the ground busbars (if any) of the cabinets. The cross-sectional area of the
short-circuiting cable is 6 sq. mm (0.009 sq. in.) and is no more than 300 mm (11.8
in.) long. Connect the two ends of the short-circuiting cable to the ground busbar
terminals of neighboring cabinets and fix them firmly.
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5 Appendix
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