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Grounding and lightning protection
The AP must be reliably grounded. Make sure the grounding points of the grounding conductor of the
AP, lightning arrestors, PE wire of the power cord, and antenna support are separate from each other,
make good contact, and are securely connected and treated with corrosion protection.
Ground resistance
The ground resistance is usually required to be less than 5 ohms, and less than 10 ohms in an area
with less than 20 thunderstorm days a year. If a piece of angle steel is buried as the grounding
conductor, the ground resistance is required to be less than 10 ohms. In an area with a higher ground
resistance, reduce the ground resistance by using brine or resistance reducing agent around the
grounding conductor.
The top of the grounding conductor must be a minimum of 0.7 m (2.30 ft) away from the ground
surface. In cold areas, the grounding conductor must be buried below the frozen soil layer.
Grounding conductor
If a grounding strip is available, connect the yellow and green grounding cable (user supplied) to the
grounding strip. To make a grounding cable, make sure the cable has a cross-section area of a
minimum of 6 mm
2
(0.01 in
2
) and a length of no longer than 3 m (9.84 ft).
If no grounding strip is available, bury a piece of angle steel/steel tube a minimum of 0.5 m (1.64 ft)
long in the earth to act as the grounding conductor. It must be zinc-plated.
•
In the case of a piece of angle steel, the size must be a minimum of 50 × 50 × 5 mm (1.97. ×
1.97 × 0.20 in).
•
In the case of a piece of steel tube, it must have a wall thickness of a minimum of 3.5 mm (0.14
in). Weld the yellow and green grounding cable of the AP onto the grounding conductor and use
anti-erosion treatment on the welding joint. With a cross-section area of a minimum of 6 mm
2
(0.01 in
2
), the grounding cable must be as short as possible and must not be coiled.
Make sure the grounding terminals of all the lightning arresters of the AP and the peer device of the
AP are reliably grounded.
Ground lead
A ground lead is a metal conductor connecting a grounding net and a grounding strip. The grounding
cable of the AP must be connected to the grounding strip. The ground lead must be 30 m (98.43 ft) or
shorter. A piece of zinc-coated flat steel with a cross-section area of 40 × 4 mm (1.57 × 0.16 in) or 50
× 5 mm (1.97 × 0.20 in) is recommended. Connect the grounding strip and the ground lead of the AP
through the yellow and green grounding cable with an area of 35 mm
2
(0.05 in
2
), or weld them directly.
Use anti-erosion treatment on the welding joint.
Power grounding (AC)
Use a power cord with a protective earth (PE). Do not use a power cord with only an L line and an N
line.
The neutral line of the power cord must not be connected with the PGND of other communications
equipment. The L and N lines cannot be connected.
Lightning rod
The lightning protection grounding (for example, the grounding of the lightning rod) must be
connected to the grounding conductor of the equipment room.
The lightning rod must be tall enough to protect the AP and its antennas.
In plain areas, the shielding angle of the lightning rod must be less than 45 degrees. In mountainous
areas or lightning areas, the shielding angle must be less than 30 degrees.
