R240D
Hardware Installation and Maintenance Guide
5 Appendix
Issue 03 (2016-01-26)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
73
Item
Requirements
devices.
Collective
ground cable
Use a ground ring or ground bar for the collective ground cable.
Do not use aluminum cables as ground cables. Adopt measures to
prevent electrification corrosion when connecting different metal
parts together.
Use a copper busbar as the collective ground cable with a
cross-sectional area of no less than 120 mm
2
(0.19 in.
2
), or use the
galvanized flat steel of the same resistance. Insulate the collective
ground cable from the reinforcing steel bars of the building.
Grounding
lead-in
The grounding lead-in should be a maximum of 30 m (98.42 ft) long.
Use the galvanized flat steel with cross-sectional area of 40 mm x 4
mm (1.58 in. x 0.158 in.) or 50 mm x 5 mm (1.97 in. x 0.197 in.).
Grounding of the
cabinet
All the devices including the surge protection device in the cabinet
must be connected in an equipotential manner. The ground cables
can be aggregated to the ground bar or surge protector socket first,
and then the ground bar or surge protector socket can be connected
to the ground.
The resistance between the device ground terminals and ground bar
cannot exceed 0.1 ohm.
The cabinet can be grounded using the protecting earthing (PE) wire
of the electrical network in the building, zinc-coated angle steel, or
the main steel bar of the building.
If the cabinet is grounded using the PE wire of the electrical
network, use a multimeter to test the grounding status. If the voltage
between the PE wire and neutral wire is lower than 5 V and the
voltage between the PE wire and live wire is about 220 V, the PE
wire is grounded well. If the tested AC voltages are not within the
ranges, the cabinet must be grounded in other ways.
The yellow-green ground cable contains multiple copper wires. The
cross-sectional area of the ground cable must be no less than 6 mm
2
(0.0093 in.
2
) and the length cannot exceed 3 m (9.84 ft.).
Ground cables cannot be twisted with signal cables.
Antirust and anticorrosion measures must be taken on the ground
terminals.
The fiber reinforcing rib can be directly connected to the ground bar
of the cabinet. Before wrapping the reinforcing rib with insulation
tape, cut a 0.5 m (1.64 ft.) segment from the reinforcing rib. Wrap
the reinforcing rib with at least five layers of insulation tape. Keep
the reinforcing rib at least 5 cm (1.969 in.) from the cabinet surface.
