STATIC STUFF - August 2014
Information on Static Control and a Bargain ... every month
Q: Do I always need to use "earth"?
A: No.
The most import thing is that there is a "common ground"; this may or may not include "earth".
Consider this ... I am wearing a wrist-strap & curly-cord, connected to a dissipative bench mat on a workbench.
If I'm only handling ESDS Devices, e.g. a PCB without using any other equipment connected to "earth" like a soldering iron, then I don't need to connect to "earth". As long as I'm at the same electrical potential as the PCB, there is no risk of an ESD.
However, If I'm wanting to handle ESDS Devices between one or more benches, then they need to be connected to a common ground, e.g. "earth" or a designated reference point.
Also, if I'm using "earthed" equipment, e.g. a soldering iron with an "earthed" tip, then my wrist-strap & dissipative bench mat must go to the same "earth" point, which is recommended to be the Mains Power Earth.