EMIT - Questions And Answers

We are operating out of an older building that has a 3 phase and Neutral AC system. The equipment ground is bonded to the Neutral Bus via the EMT and armored conduit running throughout the building. Can we use the conduit as an ESD grounding point or do we have to install a separate earth ground system for our ESD system?- Anonymous, Long Island City, NY

Yes, you can use the conduit as an ESD grounding point. The main purpose of an ESD ground or "common" point ground is to bring to "common" or the same potential all conductors in the critical working area so as to eliminate potential differences between conductors. Once the potential difference between conductors is eliminated, the ability to generate an ESD event between these conductors is minimized. YOU STILL RUN THE RISK OF AN ESD EVENT, even when all conductors in the work area are grounded because a foreign conductor can still be introduced at a different potential to your ESD ground and generate an ESD event to your grounded conductor(s). This includes a visiting engineer (ungrounded human body) delivering a needed component to you (grounded human body), IC devices sliding out of a protective tube onto your grounded table mat, a circuit board transported onto a conductive tray, etc.

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