Many old buildings/houses in Europe are so old that they were not built with a grounding system. I happen to live in one were this is the case. The problem is that if I want to use an oscilloscope, it picks up mains disturbances up to 1 Vpp due to the absence of grounding.

What options do I have?

My building has a grounding only on some outlets and while I have the option to run a power cable across the building where there is earthing, I'm pretty sure this would lead to further 50 Hz radiated disturbances on the cable, I will test this as it currently is the most viable option.

I don't need to work on hazardous voltages (at worst I'll be working on 24 V DC).

Please do not remind me of why I need grounding (other than for having a decently working oscilloscope). I am aware of that, and I try to be as cautious and safe as possible when dealing with any kind of electrical system.

  • 1
    \$\begingroup\$ Drop a 2.5 mm² earth conductor out the window and drive an earth rod in. Alternatively see how well the water pipes are connected to earth and attach there. You need to complain to the owner of the building. That's just not safe. \$\endgroup\$ – Transistor May 27 '18 at 21:25
  • \$\begingroup\$ I am not quite sure why this is an issue, can you describe your measurement setup more? usually the scope displays the potential between the ground clip and the probe tip, thus you can even run everything floating just fine. \$\endgroup\$ – PlasmaHH May 27 '18 at 21:26
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    \$\begingroup\$ Neither the "rod", radiator, nor pulling an extension cord from another room are legal options, at least not where I live. \$\endgroup\$ – pipe May 27 '18 at 22:05
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    \$\begingroup\$ You say there is 1V displayed on the the scope - Try shorting the probe tip to the ground clip - it should disappear. This 50Hz signal should not be visible when you have the tip connected to a signal you are probing. I have intentionally disconnected the scope ground in some cases to avoid ground loop problems. The signal is really there and being picked up by the probe acting as an antenna - it may have nothing to do with grounding. \$\endgroup\$ – Kevin White May 27 '18 at 22:15
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    \$\begingroup\$ You are talking about an 'earth' which is different from a 'ground' A scope can work perfectly without earth. e.g. I have one which can run on batteries: no earth whatsoever! \$\endgroup\$ – Oldfart May 27 '18 at 22:25

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