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There is nowhere to ground; I don't have access to a copper rod that goes into the earth or to circuitry. In this room there are only wall outlets and a Czech hedgehog that is no longer used. It's not connected to anything but since it's so big and I need a ground would I be able to ground shielding to it so that EMI in my devices is reduced?

ocrdu
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max
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    Most probably not allowed and won’t help anyway. Any water faucet or radiator nearby? – winny Jul 27 '22 at 21:32
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    Good to hear you no longer need to use your Czech hedgehog. It's no use as ground, unfortunately. – ocrdu Jul 27 '22 at 21:36
  • @winny there is an I-beam and a metal plate in the ground though I'm not sure if they are grounded or not. Is there a way to check with a multimeter for that? – max Jul 27 '22 at 21:43
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    I'm having a little trouble visualising this situation in which you have wall outlets and an anti-tank defence obstacle, but that aside is there no Earth at the sockets? – Ian Bland Jul 27 '22 at 21:54
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    Certainly. Push something long and conductive into the ground. Water the soil around it. Measure the resistance between your ground rod and said beam. – winny Jul 27 '22 at 22:19
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    If you were to bury your caltrop where ye may, it would almost certainly make a great earth, assuming you're not living somewhere soilless (like Greenland). Grounding isn't complicated in that sense: you just needs something literally connected to the literal ground. As they say in the standards "connected to the general mass of the earth". If you have any kind of floor between you and the earth it won't work well. We're talking agriculture not architecture here. – Dan Sheppard Jul 27 '22 at 22:32
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    In many cases in electronics, "Ground" is simply the place in the circuit that the designer chooses to call "Zero Volts". In this case, "Ground" does not imply a connection to the Earth or to anything outside the circuit. We can talk about this sort of Ground in a portable, battery-operated device, or in a car or even aircraft. – Peter Bennett Jul 27 '22 at 23:07
  • @IanBland Idk if the sockets have earth. they might and I'll try winny 's method with the rod and water since the museum is on the first floor and report back – max Jul 27 '22 at 23:48
  • If you only have 2 pin wall outlets it may be possible that there is a metal box in the wall containing the outlet (receptacle). In some cases the metal box could be earth grounded. If that is the case you could add a wired connection to the metal box or replace the receptacle with a 3 pin type with a connection to the grounded box. – Nedd Jul 28 '22 at 02:19

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No. You can't connect to a huge piece of metal that is electrically unconnected and floating to ground mains devices.

It also is likely that it does nothing if you have a device with shielding and connect the shielding with a wire to a huge metal object. If the device radiates EMI, and already has a metal shielding, it would likely make things worse, if the shielding is connected to a wire and huge metal object as those can act as additional antennas for EMI.

If you need grounding for grounded outlets, hire an electrician.

If you need to reduce EMI on a device that's shielded, it just needs better shielding, or other redesign to not radiate so much through shield.

Justme
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  • I think you've misunderstood the question. OP's talking about an signal shielding ground to reduce EMI, whereas you're answering for a safety earth... – TonyM Jul 27 '22 at 22:21
  • @TonyM You might be right, but OP does say ground is needed, so the metal object still is no ground and connecting any devices needing ground to it would have no ground. On the other hand, it would at least equalize the ground potentials between devices, but same would be achieved by just connecting ground wires between devices without the huge metal object. – Justme Jul 27 '22 at 22:28
  • If it wasn't clear - I am more interested in the general application of Czech hedgehogs for grounding not for the situation of EMI shielding specifically – max Jul 27 '22 at 23:46
  • Czech Hedgehogs are not generally recognised as a grounding method. You need something electrically well connected to ground. Where are you? Most wiring systems have Earth, so you just use a 3 wire power cord. – Ian Bland Jul 28 '22 at 01:19