Grounding Requirements - Cisco BWX 8305 Installation And Commissioning Manual

Chapter 5 Pre-installation
External power source / supply considerations for the - 48V and + 24V BS chassis:
Note
a. An external method of disconnecting each of the DC power Load/Return lines to the BS chassis is
required, either through fuse+disconnect device(s) or a dual-pole breaker. The fuse/breaker rating must
be minimum 10% higher than that of the BS Chassis breaker but shall not exceed 70A.
b. The external DC power source, if current limited, shall have the limit set-point configured higher than
the BS Chassis breaker rating.
c. The external supply "Return" and the BS chassis shall be bonded to a common Earth ground. The BS
Chassis has an external ground lug provided.
d. Do not remove protective earth connection before disconnecting the BS from the DC power supply.

5.14.2 Grounding Requirements

The BS requires an earth ground connection. Grounding from copper point to copper point shall be less
than 1 ohm. Grounding from copper point to earth ground shall be less than 5 ohms. All power and
grounding conductors must be mechanically supported to avoid strain of the wires and connection points.
AWG #6 is used between the equipment and the bus bar, and AWG #2 is required from the bus bar to the
earth ground. Always refer to the regulatory standards for power and grounding.
5.14.3 Lightning Protection
Every BS automatically comes with Secondary (built-in) lightning protection. The Service Provider
should purchase Primary lightning protection (available from Cisco). Lightning protection helps to
protect the BWX Basestation Antenna, BS, and RF lines against tower lightning events occurring at the
BS. While not absolute, the Primary protection greatly reduces the possibility of damage to the
equipment.
Cisco does not warrant equipment damaged by lightning (direct or indirect).
Note
Figure 5-1
recommended configuration. In addition to tower lightning events occurring at the BS, lightning events
that occur miles away from the BS can generate intense electrical currents traveling over the power
and/or backhaul lines and into the BS equipment, damaging it. For this reason, Cisco strongly
recommends adding the primary surge protection as well as surge protection devices at the power and
backhaul demarcation points.
OL-16336-02
below shows a BS with both Primary and Secondary surge protection, which is the
BWX 8305 Basestation Installation and Commissioning Guide
Confirm Power & Grounding Readiness
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