ESD wrist strap construction: Which component is built into a standard anti-static wrist strap lead for safety and charge control?

Introduction / Context:
A proper ESD wrist strap safely bleeds off static charge from a technician's body while preventing hazardous currents. The strap and cord incorporate a component that limits current and controls the discharge rate, protecting both the wearer and sensitive electronics.

Given Data / Assumptions:

• Standard ESD straps connect to ground via a coiled cord.
• They must prevent sudden discharges and limit current if inadvertent contact with energized parts occurs.
• Question asks which component is inside the strap/cord assembly.

Concept / Approach:
The key element is a high-value series resistor, typically around 1 megaohm. This resistor limits current flow to microamp levels while allowing slow, controlled equalization of potential between the technician and ground. No surge protector, capacitor, or voltmeter is installed in a standard strap; some facilities use strap testers separately to verify continuity and resistance before work.

Step-by-Step Solution:

Verification / Alternative check:
Use an ESD strap tester or ohmmeter to measure strap resistance end-to-end; readings near 1 MΩ confirm the built-in resistor.

Why Other Options Are Wrong:
Surge protectors and capacitors are not used in cords; voltmeters are separate test devices; “None of the above” contradicts standard ESD strap design.

Common Pitfalls:
Bypassing the resistor (unsafe), attaching to ungrounded metal, or using damaged cords which defeat ESD protection.

Final Answer:
Resistor