Appendix G: Technical Bulletins
G.1 Rajant Best Practices: Grounding and Surge Protection
July 11, 2018
Copyright © 2018, Rajant Corporation. All rights reserved.
G.1.1 Introduction
The Rajant BreadCrumb product line is designed to withstand the toughest conditions imposed by mili-
tary and industrial scenarios. Although some basic protection from electrical surges is built into the de-
sign, this protection is not adequate to compensate for the damaging effects of high-energy electro-static
discharge or lightning strike events. To ensure reliable operation and long service life, additional mea-
sures need to be taken to protect BreadCrumb equipment from electrical surges.
Important
Important
Rajant equipment will most likely not survive a lightning strike even if the grounding and surge protec-
Rajant equipment will most likely not survive a lightning strike even if the grounding and surge protec-
tion best practices detailed in this document are followed.
tion best practices detailed in this document are followed.
Important
Important
It is not necessary for a lightning strike to hit equipment directly in order to cause damage. The electro-
It is not necessary for a lightning strike to hit equipment directly in order to cause damage. The electro-
magnetic forces caused by lightning are so powerful that even a strike that lands near the equipment
magnetic forces caused by lightning are so powerful that even a strike that lands near the equipment
may cause damage. The best practices detailed in this document are aimed at protecting the equip-
may cause damage. The best practices detailed in this document are aimed at protecting the equip-
ment from nearby strikes, rather than direct hits.
ment from nearby strikes, rather than direct hits.
G.1.2 Environment
BreadCrumbs are oen installed in environments susceptible to lightning, electro-static discharge (ESD),
and other high-energy electrical surge events. A dry windy environment is more likely to create a large
buildup of static energy that leads to electro-static discharges.
G.1.3 Recommendations
Rajant recommends the following best practices for installing BreadCrumb equipment (except the C1D2 –
see the C1D2 User Guide for C1D2 installation):
Use only shielded Ethernet cables with metal-shielded connectors. The metal-encased connectors
provide the continuity of the ground from the BreadCrumb case to the PoE and AC ground or protec-
tive earth ground.
Use an Ethernet surge protector for each utilized BreadCrumb Ethernet port.
Use antenna surge protectors on all pole-mounted antennas.
In order to avoid sparking and possible damage to the device, be sure to connect the surge protector
and the powered Ethernet cable to the BreadCrumb before applying power to the PoE power supply.
Always power off a BreadCrumb device prior to connecting or disconnecting external antennas.
Ground all equipment:
Ground the BreadCrumb enclosure.
Ground the BreadCrumb power supply.
Ground the Ethernet surge protector(s).
If antennas are not connected directly on BreadCrumb antenna ports and offer exposed metal
bases, then ground the bases of the antennas. If antennas are connected directly on
BreadCrumb antenna ports, then they will be grounded through the BreadCrumb enclosure.
We continue to elaborate on these recommendations in the following sections.
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