You should always keep in mind that you are maintaining a system for its user community, not for yourself, and your work as a system administrator is to keep the system serving its intended users.
System administrators are also given broad powers which also must be applied with caution, since what you can do as a system administrator is often much more than what you should do. While you may be able to shut the system down at any time, bypass any system security restrictions, and otherwise bend the system to your will in almost any way, the ability to exercise these powers does not not necessarily give you the right to use them.
Communicating with users about important system events, such as system downtime (planned or unplanned), major software or configuration changes that affect their use, and changes in policies, is one of your important responsibilities.
The System Administrator's Code of Ethics is an attempt to codify the most widely-accepted ethical considerations of system administration.