Electronic – ESD wrist wrap resistance


I use a wrist strap with 1 MOhm resistance connected to a ground Plug Adapter with 1.5 MOhm, so total series resistance is 2.5 MOhm.
Is it OK for ESD protection or would it be better to connect the wrist strap directly to ground?

I know that this resistance is to protect the operator. However, is there an upper limit on the value of the resistor so that it doesn't affect ESD protection?


Best Answer

Either is ok, The idea of an ESD band is to slowly remove charge from your body and equipment you contact. If there was no resistance, there would be two problems:

  1. Danger of electrocution if you touch a high voltage with respect to the ESD strap ground.
  2. You could have rapid voltage shifts causing ESD like scenarios.

If we look at the 8kV Human body model (180pF of capacitance) and discharge it through some large resistors, you see that the charge is gone in milliseconds typically.

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