Grounding ESD Table

Question

I work in a manufacturing plant and we are setting up new ESD benches. Essentially, the table is grounded to the ceiling of the building and then multiple work benches are connected to that bench with grounding wires.

I was using a multimeter to check this and any metal on the table worked (screws, metal plates..) but I got an open lead reading whenever I touched the top work surface. It is supposed to be an esd table with esd tabletop so how does that work? Shouldnt it be coming back with a reading and not as open?

FYI I am an industrial engineer not an electrical engineer so please explain like I know nothing

Answer 1

An ESD bench will read as an open circuit with a multimeter. They’re not meant to be very conductive, their purpose is to prevent a charge from building up on the bench, not to discharge something placed on it quickly.

Their conductance is high enough to keep them at ground potential under normal working condition, but low enough that there isn’t a shock hazard for a person coming in contact with a live wire while touching the bench surface.

Answer 2

but I got an open lead reading whenever I touched the top work surface.

The surface of an ESD bench can be more than 1MegΩ and into the 1GigΩ reading,which is really hard to read because even the best handheld meters (like fluke 289 go into 100MegΩ range.

The most important thing is to make sure that the ESD bench is not directly connected to ground (need 1MegΩ resistor for safety) and also connected to ground so it's doing its job.