Static Control Knowledge Center

Does it do any good to have ESD chairs if the floor is not ESD?

~ Mike

A chain is only as good as its weakest link. In an electrical chain, a weak link creates a breach in

conductivity. A loose or disconnected wire is the simplest example: If a wire is loose or a cord is unplugged, the chain ends; the electrical current does not reach its intended target. With static control, the idea is to discharge the built-up (static) electrical current to ground. A person can wear a wrist and/or heel strap and sit on an ESD chair, but if the floor cannot discharge the static generated by friction-walking across the floor, moving in the chair-the charge cannot flow to ground. It has no way to get there.

Remember: a static charge cannot discharge through plastic or other electrically insulative flooring materials.

Think of a person's body as an isolated conductive object (AKA a capacitor) capable of storing static electricity. Kind of like a two-legged Van-de-Graff generator. When the static-charged person approaches and then sits in the conductive chair, the static charge on the body immediately flows to the chair-until both the body and the chair share the same charge. We call this sharing potential.

An electrical charge can flow only between conductive objects. Since the floor is non-conductive, the charge remains static. In the scenario you have described, the chair and the person remain ungrounded because they are isolated from ground. There is no conductive path through the floor. If either the person or the chair make contact with electronic equipment - both will discharge to the equipment simultaneously. Without a conductive floor, a conductive chair is nothing more than another charged body looking for a place to discharge. Kind of like an accident waiting to happen.