1.6 GROUNDING PHILOSOPHY FOR EQUIPMENTS PROCESSING NATIONAL SECURITY RELATED
INFORMATION (RED/BLACK EQUIPMENTS). Grounding of equipment, conduit, and frames for safety
protection in areas processing National Security related information (RED data) is no different than any other
facility. Typically a RED and a BLACK signal ground is established by a direct connection totally within a
controlled space to an equipotential ground plane and earth electrode subsystem (see Figure 1-65). Cable
shields from the RED equipment to the RED side of the crypto are grounded at least at both ends. Cable
shields from the BLACK side of the crypto equipment through the BLACK IDF to the BLACK equipment are
normally grounded at both ends. For unbalanced signaling, signal ground is usually established by a direct
connection from an isolated signal ground bus in the RED distribution frame to an equipotential ground plane
and in turn to the earth electrode subsystem (see Figures 1-66, 1-67, and 1-68.) Figure 1-69 provides
information on the facility power and ac ground distribution system. BLACK signal ground is used to provide a
signal ground reference in the BLACK distribution frame and for signal line filters. For all aspects other than
grounding, bonding, and shielding of secure installations, refer to NACSIM 5203. Refer to Section 2.4 of this
Volume for the grounding of existing RED/BLACK equipments and systems.
Note: An equipotential ground plane is considered as earth for the signal reference subsystem of communica-
tion systems, regardless of elevation from physical earth.