Grounding Headphones for Protection Against ESD

A simple alternative technique has been devised protecting delicate equipment against electrostatic discharge (ESD) in settings in which workers wear communi-cation headsets. In the original setting in which the technique was devised, the workers who wear the headsets also wear anti-ESD grounding straps on their wrists. The alternative technique eliminates the need for the wrist grounding straps by pro-viding for grounding through the head-sets. In place of the electrically insulating foam pads on the headsets, one installs pads made of electrically conductive foam like that commonly used to protect elec-tronic components. Grounding wires are attached to the conductive foam pads, then possibly to the shielding cable which may be grounded to the backshell on the connector. The efficacy of this technique in protecting against ESD has been verified in experiments. The electrical resis-tance of the pads is a few megohms -about the same as that of a human body between the fingers of opposite hands and, hence, low enough for grounding. The only drawback of the technique is that care must be taken to place the foam pads in contact with the user's skin: any hair that comes between the foam pads and the skin must be pushed aside because hair is electrically insulating and thus pre-vents adequate grounding.

This work was done by John Peters and Robert C. Youngquist of Kennedy Space Center. For further information, contact the Kennedy Commercial Technology Office at 321-867-1463. KSCA-12295