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Suppose I would like to verify that the ground terminal on an indoor power outlet is actually connected to the ground (from what I've read, some of them aren't!). How would I go about checking that?

I ask because I recently purchased an ESD wrist strap, but I know it's useless unless it's actually connected to the earth.

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  • \$\begingroup\$ This would be best for diy.stackexchange.com. \$\endgroup\$
    – Kellenjb
    Aug 11, 2012 at 22:48
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    \$\begingroup\$ In actuality, having your wrist strap grounded to earth is irrelevant to ESD sensitive components; what matters is that it be grounded (through the large value safety resistor) to the effective ground of the environment in which you are working on them, for example an anti-static mat on a bench top. Sensibly this system would all be grounded to earth, but it should not be hard to conceptually imagine an ESD safe work environment on an aircraft. \$\endgroup\$
    – Chris Stratton
    Aug 12, 2012 at 0:31
  • \$\begingroup\$ You could always drive a copper pipe a couple feet into the ground and use that as you point. \$\endgroup\$
    – Joshua
    Mar 29, 2017 at 1:05

2 Answers 2

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You can use the continuity function on your multimeter for this, connect one end to the ground of the power outlet and the other to any other point that you know to be grounded. Not sure if there are any safety issues involved but I've done similar with my bench power supply and scope and it worked well.

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    \$\begingroup\$ But what if I don't know of a point that is grounded? Take a room in a house, for example; how would I know if any of the outlets are actually connected to the ground? \$\endgroup\$
    – Nate
    Aug 11, 2012 at 20:12
  • \$\begingroup\$ Seems I misunderstood your question somewhat, since the electrical system in houses have to be certified It's a safe assumption that all plug points are. \$\endgroup\$
    – s3c
    Aug 11, 2012 at 20:30
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    \$\begingroup\$ @s3c - That's one hell of an assumption. It's also really, really unsafe. The only assumption you should make about electrical wiring that you're working on is that it was installed by an inebriated baboon. That way, when it turns out that the yahoo who did the wiring accidentally wound up wiring things to all the conduit in the house is electrically hot, it doesn't kill you. \$\endgroup\$
    – Connor Wolf
    Aug 12, 2012 at 0:10
  • \$\begingroup\$ @Fake, I can't argue with your logic since it sure is possible. At some point you have to start assuming certain things though. With a little thought before action you can keep yourself safe. \$\endgroup\$
    – s3c
    Aug 12, 2012 at 10:31
  • \$\begingroup\$ @FakeName - So, what would you suggest? \$\endgroup\$
    – Nate
    Aug 14, 2012 at 13:19
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mains socket tester Fluke SM200 enter image description here

Socket tester checks the sockets are correctly wired with indicator lights that accurately denote no neutral, live and earth reversed, live and neutral reversed and no earth.

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    \$\begingroup\$ Technically that cannot verify that the earth is actually earthed, it can only compare it to the hot and neutral. \$\endgroup\$
    – Chris Stratton
    Aug 12, 2012 at 0:28

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