GROUND AND LOSS OF GROUND
A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation.
To avoid electrical shock, plug the power cord into a properly wired receptacle.
If this is not done or if the ground connection is lost, all conductive parts of the instrument (including some controls that may appear to be insulated) can render an electric shock.
DEFECTS IN THE SAFETY GROUND
Whenever it is likely that the protection provided by the connection to earth/ground has been impaired, the apparatus should be made inoperative and secured against unintended operation.
The operation is likely to be impaired if, for example, the apparatus: