A simple EPA (ESD Protected Area) consists of 3 things:
- wrist strap
- antistatic mat
- common point ground
When doing field service (installing/replacing hardware parts) the ESD sensitive part goes straight into a static shielding bag and the replacement part comes out of a static shielding bag and goes straight into the PC. You only need a wrist strap to bond yourself to the PC.
On a desktop PC you can connect to the conductive case. Laptops on the other hand often have a non-conductive plastic housing.
Bonding to the ground pin of an USB port is an alternative option. This means: reaching equipotential with the motherboard's ground-plane via the USB port.
- Can the USB port and/or motherboard handle the current spike? ESD damage?
- What about user safety?
- Should there be a resistor between PC and wrist strap?