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I've done some small laptop stuff without the wrist strap, but I might replace a logic board of a MacBook and will be working on it for a long time. I have wrist straps and might as well use one.

I'm real dumb when it comes to grounding stuff, sorry. Will plugging the extension cord into the wall outlet and then clipping to the cord pin ground me?

I read that clipping it to the USB metal in the laptop is not smart, so I'm not clipping it to the inside of my laptop.

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    \$\begingroup\$ It's not ground as in earth that is important, but a common ground with the work item and work surface. \$\endgroup\$ Oct 14, 2020 at 5:15
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    \$\begingroup\$ If you happen to touch something that's live at mains voltage, having your other hand connected to ground with low resistance means a lot of current is passed straight through your chest area which is very undesirable. So always make absolutely sure that there is a large (1 megaohm or more) resistor with sufficient voltage rating connected in series. Most ESD wrist straps have this, but there are also some examples around that don't, so always check. \$\endgroup\$
    – Mels
    Oct 14, 2020 at 13:59

2 Answers 2

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Using the safety ground on a three prong outlet is a valid way to ground yourself for ESD purposes. Many lab benches I have used have the ESD mat grounds attached to the ground that comes from a power cord feeding the benches.

You can also buy an ESD grounding plug for a wrist strap that plugs into the ground on an outlet. Here is one example.

https://www.amazon.com/Static-Desco-Ground-Adapter-Benches/dp/B0793LMXC8

If you are going to just use a regular extension cord, be very cautious of the fact that Line and Neutral are right there too. Make sure you go in the right hole.

Also a wrist strap is supposed to have a large series resistor built in to protect you in case it does connect to something energized. Make sure it has the resistor.

Finally, check that your outlet is wired correctly. If not, ground might not be where you think it is.

Lastly, you can ground to other things like a metal water pipe with much less risk.

Also see this question and answer.

Is it a bad idea to plug the other end of ESD strap to wall ground?

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  • \$\begingroup\$ thanks for the informative response, will do some further research before I attempt. \$\endgroup\$
    – Toddd
    Oct 14, 2020 at 3:26
  • \$\begingroup\$ The point about the resistor is pretty crucial and could do with some emphasis. A casual reader might miss it and think it's okay to 0-ohm-tie their wrist to ground with a plain copper wire or something like that. \$\endgroup\$
    – Mels
    Oct 14, 2020 at 13:54
  • \$\begingroup\$ my wrist strap the last one I bought was ifixit, 50 ohm resistance, think I'll buy their mat kit too, bit more expensive than others but they seem to be quality company. \$\endgroup\$
    – Toddd
    Oct 14, 2020 at 15:37
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Do not use an extension cord because when you chop it off, the three conductors are too close together for comfort when you connect to the ground wire. At worst, get one of those plugs ends at the hardware store to make your own extension cord. They open up with with some screws and provide 3 points inside to connect wires to. Connect a wire to the ground prong and maybe even plug up or or cover the other two mounting points with epoxy or something. Or better, yet get a purpose built one that has a metal ground prong and two plastic hot and neutral prongs.

You may also use a ring terminal connect to the screw on the faceplate of your wall outlet. That should be grounded. At least it is in North America.

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  • \$\begingroup\$ yeah, I might get a cheap ground cable and esd mat, or one of those desco things, something, not going to risk getting zapped. \$\endgroup\$
    – Toddd
    Oct 14, 2020 at 4:14
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    \$\begingroup\$ "Do not use an extension cord." is somewhat useless when you don't explain why. \$\endgroup\$
    – pipe
    Oct 14, 2020 at 11:57
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    \$\begingroup\$ @pipe fixed.... \$\endgroup\$
    – DKNguyen
    Oct 14, 2020 at 13:23
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    \$\begingroup\$ @DKNguyen Ok, but the user did not want to chop it off, just use as-is \$\endgroup\$
    – pipe
    Oct 14, 2020 at 13:26

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