Title: Ground Loops Can Cause System Damage
Keywords: Ground loops, Opto-Isolated, damage
Date: May 29, 1995
“A ground loop is a current through a conductor between two two grounded points” as in two buildings connected by an RS-232/RS-485 data line.
The potentials are different and if the voltage is great enough … a current flows down the signal ground of the data cable … and your serial port is damaged.
When two devices carry a difference in ground potential, the potential will try to even itself out … in much the same way as water seeks its own level. It will travel through the the lines and connectors and overload the circuitry of both the high-potential and low-potential device.
** A lightning strike or electrical spike … is a sudden event causing damage … smoking chip/traces.
*** A ground loop is more insidious … and is a long term steady event that weakens the chip … and slow cooks the chips and they eventual fail … blackened tops and melted circuit boards.
Note: A surge protector does NOT guard against ground loops.
The best prevention for ground-loop problems is to use optical isolation on long data lines.
End of KDB-105