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Can an isolated AC system like a generator which is not system grounded will be able to give me a shock if I touch it one wire? I guess it should not, because then there would not be a path back to the source (the generator). But I highly doubt it and I was proved wrong in case of an inverter whose none of output wire were tied to ground still was able to glow a neon test screwdriver... But an isolated DC system (like a battery) will behave as I had thought. No current would flow through my body to ground if I touch it...

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  • \$\begingroup\$ “No current would not flow...” so it would or it would not? \$\endgroup\$ – Solar Mike May 18 '18 at 14:38
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There is a nice example: Tucker Phone. https://en.m.wikipedia.org/wiki/Tucker_Telephone

When i was in the military, tried it on myself, it's quite painful.

Of course, you have to hold two wires with two hands.

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  • \$\begingroup\$ Upon my observation very small amount of current still flows across my body which means some voltage is there. It is because of capacitive coupling. Can anyone explain it to me? \$\endgroup\$ – ObsessionWithElectricity Jun 1 '18 at 4:14
  • \$\begingroup\$ "Of course, you have to hold two wires with two hands." means that your story is not relevant to the situation of the question. \$\endgroup\$ – Chris Stratton Jul 6 '18 at 14:42
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Short answer is yes.

I once had an "isolated" generator that was not system grounded. I thought I was safe from shock. Turns out, you can get quite a healthy shock.

Isolated in terms of a generator generally means the neutral is floating, not that it is 100% isolated from ground. To prove it to yourself, take a multi-meter, and measure the voltage from the "isolated" neutral to earth ground. My generator measures about 60V, and gives you quite the tingle if you touch it!

Longer story: I was working on a branch circuit on my cabin, the breaker was "off" but my isolated generator was running to power the other circuits. I touched the neutral wire and received a very healthy shock. I touched it again out of disbelief, and shocked my self again. It was when I measured the neutral wire with my DMM, I realized that my isolated generator was not as isolated as it should be.

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  • \$\begingroup\$ I tried an experiment with my inverter which outputs 240V AC which is an example of ungrounded system.I measured the voltage of both output wires wrt ground and I found 0 V. Is it safe now to touch wires (not intending to do so) . But my neon test screwdriver still glows very dimly I guess if voltmeter can't show reading the current shouldn't be high enough to shock me.. \$\endgroup\$ – ObsessionWithElectricity May 19 '18 at 3:26
  • \$\begingroup\$ What do you mean by healthy shock? Does it mean lethal as mains shock or very mild like a slight tingle. \$\endgroup\$ – ObsessionWithElectricity May 19 '18 at 5:51
  • \$\begingroup\$ Did you set your Multi-meter to Volts AC? 0 V is a suspicious reading. Do you get 240V when you connect to both the output wires? What were you using for a ground reference? As for the neon test screwdriver, it works using your body as a ground reference. Is your screwdriver the isolated tip or non-isolated tip? And as for the shock, voltage as low as 30 V can be lethal. All it takes is a small current running through your heart to cause it fibrillate. When I work on mains power, i use the one hand rule. My other hand stays in my pocket! \$\endgroup\$ – David Drysdale May 22 '18 at 15:25
  • \$\begingroup\$ I used my water pipeline as ground reference and my Voltmeter was set to ACV and yes I get 240V connecting both wires. The screwdriver glows very dimly (you have to look into it to notice) but yes i got slight tingle when I touched the wires. \$\endgroup\$ – ObsessionWithElectricity Jun 1 '18 at 4:12
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An AC generator is not the same as an DC battery.

If you have an unconnected thousand volt battery, you can safely touch one of the terminals. Because it is DC.
Not both obviously, since then you'd have an electrical path.

However, with AC, the electrical path will include capacitors.
For a generator for example, all the winding in the grounded housing will have a parasitic capacitance to ground. So will you, the large body of water walking on the ground.

Can an isolated AC system like a generator which is not system grounded will be ble to give me a shock if I touch it one wire?

Yes, if there is enough leakage current.
Which is why a Tesla coil works with fluorescent lights, if you hold them.

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