ESD Systems - Questions And Answers

Knowing well that the human body resistance is in the range of 10⁶, I was wondering why some of the specification set for the ESD shoes on the body to ground is 8 x 10⁵? Isn't this too risky for the human? - June Tan, Kuala Lumpur, Malaysia

Actually, the resistance of the human body (skin) will vary greatly; from 1,000 ohms to well over 10 Megohms. The ESD Association uses in it’s ESD-STM5.1-1998, HBM (Human Body Model) a resistance of 1.5 kilohms. Footwear falling in the range of 800,000 ohms (8x10⁵ ohms) can still be considered safe if the person is working in a standard industrial work area, where the working power is under 250 VAC. It is the current level you want to control and an 800 kilohm resistance is sufficient to keep the current at a safe level according to MIL-STD-454, All personnel ground straps should have sufficient resistance to ground to limit current to the perception level as shown in MIL-STD-454, Requirement 1, DOD-HDBK-263, Section 7.3.1.3, Table VIII, (Ref.: MIL-STD-454).

Related Categories: