What causes voltage between AC Mains phase and me?

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Discussion Overview

The discussion revolves around the phenomenon of measuring voltage between the AC mains phase and a person's body, specifically addressing the observed voltage readings when using a multimeter in different conditions. The scope includes conceptual understanding of electrical principles and safety considerations.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why a multimeter shows different voltage readings (150 volts on the floor and 80 volts on carpet) when measuring between their hand and a socket's phase wire, suggesting a need to understand the underlying causes.
  • Another participant introduces the concept of parasitic capacitance, explaining that the body has capacitance to Earth ground, which may create a voltage divider effect with the AC mains.
  • A different participant mentions capacitive coupling as a reason for the observed voltage or current, indicating that this is a common phenomenon in such measurements.
  • One participant discusses the role of the multimeter's impedance and grounding resistance in affecting the voltage readings, suggesting that higher resistance leads to lower current and thus alters the voltage drop measured.
  • A cautionary note is raised about the dangers of measuring current in such situations, emphasizing the risks associated with improper use of a multimeter when connected to line voltage.

Areas of Agreement / Disagreement

Participants present various explanations for the observed voltages, indicating multiple competing views on the underlying causes. The discussion remains unresolved as no consensus is reached on a singular explanation.

Contextual Notes

Limitations include potential misunderstandings of electrical principles, the influence of environmental factors on measurements, and the dependence on the specific conditions under which measurements are taken.

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TL;DR
what causes voltagebetween my hand and phase wire
So my question is that if i put other lead of multimeter to my hand and other lead to socket 230 phase wire why it shows 150 volts when i stand at floor and 80 volts when i stand at carpet? what causes those voltages? And yes i know doing that could be dangerous. It also shows weird voltage if i put other lead to 230v and other lead to my pc body when pc is not even connected to socket. In that case i got 180 volts.
 
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Welcome to PF.

Are you familiar with the concept of parasitic capacitance? Your body has parasitic capacitance to Earth ground (and other metal stuff around you), so you are seeing a voltage divider across your parasitic capacitance to AC Mains and Earth Ground.

1706886112335.png


https://incompliancemag.com/article/human-body-model-and-electrostatic-discharge-esd-tests/
 
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Welcome to PF.

You are seeing the voltage or current that flows when there is capacitive coupling between objects and various AC voltages.
 
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The multimeter presents the voltage drop between its connecting points. That means, this voltage is proportional with the current flowing through the multimeter impedance-I think mainly through a reactance [inductive].However, the circuit passes through grounding resistance ,your body and the floor and how this resistance is more elevated the current is lesser, so the voltage drop through the multimeter. Then, when the carpet resistance is inserted in this circuit then the current will be lower and so the voltage on multimeter.
 
Something like this
The current through your body.jpg
 
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Just as a reminder: if the internal resistance of the multimeter is not present (for example, because somebody trying to measure the current in such situation and set it to measure current - seen that happen) then the whole experiment becomes life threateningly dangerous.

Best not to fiddle with anything connected to line voltage. Not even with a multimeter.
 
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