7.5 Flooring & Grounding Architecture

The floor serves as the primary ground path for mobile personnel and carts. It must be conductive enough to drain charge but resistive enough to protect personnel from electric shock.

7.5.1 Resistance Requirements (ANSI/ESD S20.20)

• System Resistance (Person + Footwear + Floor): Must be < $3.5 \times 10^7$ ohms ($35$ megohms) when measured per ANSI/ESD STM97.1.
• Walking Test (Body Voltage Generation): Peak voltage accumulation on a person walking must be < 100 Volts.

7.5.2 Grounding Hardware

• Common Point Ground (CPG): Every workstation must have a CPG block that connects the mat, the wrist strap, and the equipment chassis to Earth.
• Hard Ground vs. Soft Ground:
  • Equipment chassis: Hard Ground (0 Ohm).
  • Personnel/Mats: Soft Ground (1 Megohm resistor in series) to limit current to safe levels (< 5mA) in case of accidental contact with live voltage.

Final Checklist