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NE40E V800R010C10SPC500 Installation Guide

This is NE40E V800R010C10SPC500 Installation Guide

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Requirements for Lightning-Proof Grounding

Requirements for Lightning-Proof Grounding

Table 2-16 lists the requirements for lightning-proof grounding.
Table 2-16 Requirements for lightning-proof grounding




Use reinforced concrete for the construction of the equipment room.

Install a lightning-proof device like a lightning rod in the room.

The lightning-proof ground must be connected to the same ground busbar as the protection ground of the room.

TN-S power system

Use a special power transformer for the telecommunication site. Use a metal jacket or steel tube to cover the power cables before burying them under the ground. Ground both ends of the metal jacket or steel tube nearby. Less than 15 m (49.21 ft) of the metal jacket of steel tube should be buried.

Install a gapless zinc oxide arrester to each of the three phase lines at the low-voltage side of the AC power transformer. The enclosure of the transformer, the neutral lines at the low-voltage side, and the metal steel tubes of the power cables that are connected to the enclosure of the transformer should all be grounded nearby.

Lightning arresters for power cables

Do not route the AC/DC power cables in/out the communications site overhead.

After the low-voltage power cables are led into the room, install the lightning arrester for the power cables in the AC voltage stabilizer and the AC power distribution panel (box). Ground the arrester nearby.

For an equipment room in a city, install the power supply arrester with a nominal discharging current of no less than 20 kA. For an equipment room built in the suburbs subject to lightning strikes, install the power supply arrester with a nominal discharging current larger than 60 kA. For an equipment room in a mountainous area subject to lightning strikes, or in a detached high-rise building in a city, install a power supply arrester with the nominal discharging current larger than 100 kA.

The ground cable of the lightning arrester should be a maximum of 1 m long.

DC power distribution grounding

Connect the DC working ground (positive pole of the -48 V DC power supply or the negative pole of the 24 V DC power supply) with the indoor collective ground cable nearby. The ground cable should meet the maximum load of the equipment.

The power equipment must have a BGND cable, which can connect the power equipment to the collective ground cable of the telecommunication site (or the protection ground bar of the equipment room).

Equipotential bonding

Ground the devices and auxiliary devices, such as mobile base station, transmission, switching equipment, power supply equipment, and cable distribution frame, in the equipment room. Connect all protection ground cables to the collective protection ground bar. Connect all protection ground cables in one equipment room to one protection ground bar.

Apply joint grounding to the working ground and protection ground of devices, which means the two share one grounding network.

The cabling tray, rack or shell, metal ventilation pipe, metal door or window of the equipment should be grounded for protection.

General requirements for grounding

Do not connect the neutral line of the AC power cable with the protection ground of any telecom equipment in the equipment room.

Do not install a fuse or switch on the ground cable.

All ground cables should be as short as possible, and should not be coiled.

Grounding resistance

The grounding resistance must be lower than 1 ohm.

The upper end of the ground busbar should be at least 0.7 m (2.30 ft) over the ground. In cold areas, bury the ground busbar below the frozen ground.

Measure the grounding resistance periodically to ensure effective grounding.

Routing of signal cables

Do not arrange the signal cables overhead in the equipment room. All signal cables must be led into the site underground.

Use cables with a metal jacket or place them in a metal pipe if they go into or come out of the equipment room.

Keep the ground cable of the lightning arrester as short as possible. Ground any idle lines inside the cable in the equipment room.

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 with a cross-sectional area not less than 120 mm2 as the collective ground cable, or use 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 galvanized flat steel with cross-sectional area of 40 x 4 mm (0.16 in.) or 50 x 5 mm (0.20 in.).

Updated: 2019-01-03

Document ID: EDOC1100055059

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