This question is about ESD-protection while installing/removing components (RAM, SSDs, etc.) inside a PC.

When grounding the GND of an USB-port to earth or to my wrist strap (as advised earlier) the moment-of-contact would be the moment i plug the USB-cable (which is attached to my wrist strap somehow) into the USB-port.

So, the USB-port is the point-of-contact where an ESD-event (due to a potential-difference) could happen at the moment-of-contact.

In theory, is the USB-port better protected when the resistor is nearby?

(Maybe far fetched question, but i'm wondering on which end of my self-made cable i should place a resistor.)

  • \$\begingroup\$ To connect the GND of an USB-port to earth or to my wrist strap, i should make a cable myself or rebuild an existing USB-cable. The question is: should i put the 1E6 ohm resistor (inside my self-made cable) on the end near the USB-port or on the other end? \$\endgroup\$
    – user127725
    Commented Dec 18, 2016 at 15:06
  • \$\begingroup\$ Ignore what I posted just now, I just read your other question and got a different context for the question. \$\endgroup\$
    – Majenko
    Commented Dec 18, 2016 at 15:06

1 Answer 1


There is no difference in having the resistor by the USB plug or by the wrist strap - it's in series, so the location has no bearing on things.

The "moment of contact" is the moment when the path between your wrist and the USB socket is made. That could either be when you have the strap attached and plug it in, or put the wrist strap on when it's already plugged in. Either way it's via the resistor.

The only "improvement" in the location of the resistor would be to have it inside the laptop. That way, if you happen to be touching the metal shield of the USB connector with your finger as you plug it in, the resistor would still be in the path. That's the only time the resistor in your cable would possibly be ineffectual.


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