Desco - Questions And Answers

Why do some ESD ground cords have resistors in them and others don't? - Anonymous, Boston, MA

ESD Ground cords serve one purpose, to connect a conducting surface to the same potential as your power ground. A "hard ground" is a connection to ground using a ground cord without any added resistance; essentially at zero Ohms between power ground and your common point snap. A "soft ground" is a ground cord with a built-in series resistance, typically 1 Megohm, designed solely to limit any potential current the operator may come in contact with when exposed to 110 VAC and up to 250 VAC maximum. The resistorized cord is used to provide additional safety to the operator. The ESD Association, ANSI EOS/ESD S6.1-1991, recommends grounding your ESD bench top or floor mat with a hard ground.

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