In electronics ESD practice, what is the best grounding method for a conductive workbench to safely discharge static while servicing PC hardware?

Introduction / Context:
Electrostatic discharge (ESD) control is critical when servicing computer hardware. A conductive workbench surface, wrist strap, and proper grounding prevent damaging voltage spikes from building on you or the equipment. Choosing the best ground reference ensures charge equalization happens safely and predictably.

Given Data / Assumptions:

• The bench has a conductive (or dissipative) surface intended for ESD control.
• We are working on typical PC hardware (motherboards, memory, cards, drives).
• We want the preferred grounding point for the bench mat/system.

Concept / Approach:

The ESD benchmark is to reference all items (technician, bench, and device-under-test) to the same electrical potential—usually the equipment chassis which is bonded to a verified protective earth. Chassis ground (earth-referenced) keeps the device and the work surface at the same potential, minimizing ESD events.

Step-by-Step Solution:

Verification / Alternative check:

Most ESD standards and service manuals recommend a common point connected to equipment chassis ground which is bonded to building safety earth. This provides a safe, low-impedance return while limiting fault current via series resistance in straps.

Why Other Options Are Wrong:

• AC outlet: plugging directly to an outlet hole is unsafe; only the outlet’s earth pin via a certified ESD ground block is acceptable, not the live/neutral conductors.
• To another device: creates floating references; if that device is not earth-bonded, ESD remains uncontrolled.
• Ground to bench: the bench itself is not a ground; it must be bonded to a proper chassis/earth point.
• None of the above: false because chassis ground is correct.

Common Pitfalls:

• Clipping to painted metal (insulated) instead of bare chassis ground metal.
• Assuming any metal is earth; verify with a tester.
• Bypassing the 1 MΩ safety resistor in wrist straps.

Final Answer:

Chassis ground.