IBM 7316-TF4 Manual page 15

Note: All Ethernet cables must be shielded and grounded at both ends.
The ac-powered system does not require the use of an external surge protection device (SPD).
The dc-powered system employs an isolated DC return (DC-I) design. The DC battery return terminal
shall not be connected to the chassis or frame ground.
The dc-powered system is intended to be installed in a common bonding network (CBN) as described in
GR-1089-CORE.
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Safety notices