Tripp Lite NGI-S04C2 Owner's Manual page 5

interconnection methods, unless the exposed metal parts are located
within a restricted access location and users and service people who
are authorized within the restricted access location are made aware of
the hazard. A restricted access area can be accessed only through the
use of a special tool, lock and key or other means of security.
Warning
No user-serviceable parts inside. Do not open.
This equipment must be grounded. Never defeat the ground conductor
or operate the equipment in the absence of a suitably installed ground
Warning
conductor. Contact the appropriate electrical inspection authority or an
electrician if you are uncertain that suitable grounding is available.
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