Safety Rules to Prevent Electrical Shock
● If possible, turn off all power while working inside an instrument, when removing covers
and panels, when attaching a probe to a high-voltage test point, when working in
tight quarters, and whenever you leave a device with exposed high voltage.
● If power must be on, use only one hand. Keep the other hand in your pocket, where it cannot
contact another part of the system to provide a path for current through you. There
must be a path for current and a voltage difference before an electrical shock can occur.
● Interlocks are designed for a purpose. Carefully consider the safety consequences
before defeating interlocks.
● Use insulated tools whenever and wherever possible.
The purpose of the third or “ground” wire in an instrument’s power cord is to protect the
user or handler of the equipment from electric shock. Using ungrounded devices increases
the risk of electric shock. It is important to realize that the equipment will operate perfectly
well without the ground wire intact. The only way to tell whether a device is
grounded is to measure continuity from the ground pin of the power plug to the chassis.