Posted 10 December 2011 - 06:03 AM
Romeo, I would like to offer one proviso to your comment if I may?
It's true that the requirement for prevention of ESD is maintaining you and the equipment at (approximately) the same potential. This doesn't require the equipment to be earthed.
The potential (pun intended) risk of having the equipment not earthed is that the common potential is indeterminate with respect to earth, and this common potential is only maintained by the safety series resistance (at least 1 Meg Ohm, can be up to 10M). If your body potential suddenly changes greatly, it's possible you could touch an ESD sensitive component before the bleed current has time to equalize the potential. The most likely thing to suddenly change your body potential is touching something that is earthed, such as another device, lamp or whatever. So in the absence of a complete ESD workstation, having the equipment you're working on earthed neutralizes this scenario, and removes an unknown quantity from the equation.
John, have you considered that having yourself connected to earth in a way that will conduct lethal current and you cannot detach from yourself by falling, could prove fatal if you contact live mains? As I mentioned above, an ESD wristband has a safety series resistance included for this reason.
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