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I want to check whether the earth pin of the electric AC wall socket is really connected to earth. But I only have access to the socket’s phase, neutral and earth inputs.

I have no access to any known ground point as well.

I also have a voltmeter with continuity tester. How can I verify if the earth pin is floating or really connected to the earth?

Would measuring the voltage between the phase and earth reveal whether the earth pin is earth grounded or floating? (assuming neutral and earth are connected somewhere at the appliance)

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  • \$\begingroup\$ Do you have access to a nearby sink or water faucet? \$\endgroup\$
    – winny
    Commented Sep 20, 2023 at 19:02
  • \$\begingroup\$ I dont. All I have is written in the question. \$\endgroup\$
    – GNZ
    Commented Sep 20, 2023 at 20:06
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    \$\begingroup\$ That certainly complicates things. What country are you in and more specifically, what grounding system does it use, TN-C? TN-C-S? \$\endgroup\$
    – winny
    Commented Sep 20, 2023 at 20:35
  • \$\begingroup\$ TT as far as I know. \$\endgroup\$
    – GNZ
    Commented Sep 20, 2023 at 23:12

1 Answer 1

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The following checks are to be carried out to confirm that the 'earth' pin of the wall socket is properly earthed and also that there is no connection between its 'neutral' and 'earth' pins.

  1. With the mains isolator switched 'on', measure the voltage between 'line & neutral' and 'line & earth'. Both should measure 230 V ~ as shown in the schematic.

enter image description here

  1. With the mains isolator switched 'off', check for continuity between 'neutral & earth'. There should be no continuity.

P.S. As confirmed by the OP, the TT earthing system has been taken into consideration.

enter image description here

Image Credit: Earthing system - Wikipedia

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    \$\begingroup\$ This just confirms that N and PE are connected at some point, but not that PE is actually grounded. \$\endgroup\$ Commented Sep 22, 2023 at 5:38
  • \$\begingroup\$ @the busybee - Hi, Got it, thank you! I have edited my answer. \$\endgroup\$
    – vu2nan
    Commented Sep 23, 2023 at 7:39
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    \$\begingroup\$ @vu2nan I still don't get it. There are no instructions how to determine if PE is really connected to soil of planet Earth for potential equalization. And obviously the PE must be bonded to Neutral so it can't be floating from Neutral. If PE is floating from Neutral, if you have a metal cased device (e.g. desktop PC) the PE must be connected to metal case in order to protect from shocks, if Live wire insde supply connects to metal case. Where would this "mains isolator" be? \$\endgroup\$
    – Justme
    Commented Sep 23, 2023 at 7:51
  • \$\begingroup\$ @Justme - Hi, Voltage of 230 V ~ between 'line & neutral' and 'line & earth' indicates that 1. The earthing is proper or 2. There is a connection between the 'neutral' & 'earth' pins. With the continuity check confirming that there is no connection between the 'neutral' & 'earth' pins, it may be concluded that the earthing is indeed proper. In the TT earthing system, the neutral is earthed at the utility supplier end and the equipment at the consumer end. \$\endgroup\$
    – vu2nan
    Commented Sep 24, 2023 at 2:07

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