I once experienced a startle shock under a HV tower. We were beaching a small sailboat. When we came under the transmission lines, we got a shock when we touched the sailboat mast or wire shrouds.

 

Mains frequency electrical fields DO EXIST, and they certainly can deliver some energy. BUT, since you are still here, it must have been a small portion.

 

Fyi.
I happened to be in London today .
Whilst riding on the underground , you see a good few sparks from the pickups , and lots of interference , including. Local radio repeaters on the tunnels . And large ac traction control machinery .

A very electrically noisy environment.

As mentioned previously , I use a portable 6 lead ECG ..
. ..
. Here's the trace I took whilst train running.

Evidently I was not earthed, and it's far from a Faraday cage , but the ECG works on an equipotential principle , my body and the test equipment float together .
Not that lack of interference.

 

OK, so battery operation inside a enclosure in an electrically noisy environment can succeed. I guess, since I don't know if that plot was noise free or not. I am suspecting that it is noise free. Of course, the underground car is a uniform potential shield. BUT, no noisy switcher power supply was connected.

 

walking on the carpet will yes make a voltage ,
but thats an external power being bought onto the metal plate.
no need to dissipate it to earth, if your floating metal plate is connected to you, and all the equipment is connected to the metal plate, whats the voltage difference between you and the plate ? whats the voltage between the plate and the equipment ?
no where is any of that connected to the water , what current flows in this case do you think ?

I've been pondering a lot on this and I asked other engineers at physics stack exchange. So I can't make a new thread because it's a follow up to the above statement and I can't start a thread by quoting other web sites (because we don't know if All about Circuits and Physics Stack exchange moderators are at odds or in harmony).

Drjohsmith. You mentioned about a 6 x 6 meters pan or metal plate. Supposed all the participants here in this thread are standing on the metal plate barefoot. And I got a huge static. Won't the static travel to the plate? There may not be potential difference, but supposed I got struck by lightning, won't the charge flow to the entire metal plate and shock all of you too? (even if the plate is at same potential)?

I asked the following to someone at physics stack exchange:

I asked: " I want to know what is the unit of potential in potential equalization? For example, if we are in a room connected together with wires and we are NOT earthed, and someone got static, so the static will not flow among us since we have same potential? voltage doesn't flow with same potential. But what is the unit of potential, voltage per meter? For different room with different connected people not earthed. They are in another potential like 10 volt/meter vs us connected in a room which are 30volt /meter? . Or is the unit of potential the static itself? "

He answered: " If someone receives static then that static electricity has two poles; one at earth/ground (that we sometimes forget about) and the other one is a high voltage <-- this is what causes a small surge of current to flow into an insulated body. Current flows into that body due to that body's capacitance to earth/ground (several hundred picofarads). So if three bodies are insulated but connected electrically together then, a 3 times current surge flows and all three bodies rise to a significant potential until "the capacitance" has charged up"

I asked: "but if I'm connected to the device I'm repairing with a strap (not connected to earth and not connected to mains of course), we are at same potential, and there is no voltage difference. How can static flow from me to the device? Isn't the purpose of having same potential as the device being worked on to avoid static discharge from me to the device. if we are connected by wire, you mean static from me can still affect the device since you mentioned about "current surge flows" above? "

He answered: "Static electricity is, by the name implies static i.e. unmoving as a result of a surge of energy settling down. However, if an electric surge is introduced then a current will flow for a short time and it can flow to your device and, potentially damage it. ".


So, MrChips, drjohsmith, Misterbill2, Alec_t, and others who can fit. if we are standing in the 6 x 6 meter metal plate and I got struck with huge static or lightning, it can also affect all of you, won't it?

 

if we are standing in the 6 x 6 meter metal plate and I got struck with huge static or lightning, it can also affect all of you, won't it?

All would be raised to the lightning potential (which is relative to ground), but no current would flow unless the assembly had some path to ground. Parasitic capacitance or conductance could provide that path (and usually does).

 

Metal plate or no metal plate, if you got hit by lightning you will die.
Don’t try this at home.

 

All would be raised to the lightning potential (which is relative to ground), but no current would flow unless the assembly had some path to ground. Parasitic capacitance or conductance could provide that path (and usually does).

@Secan
you can always start a new post,
esspecialy as this one has been answered many times.

@Alec_t says,
you would be at equi potential,
but ,there are many caveats ,
start a new thread on lightening, being thousands / millions of amps , it has a significant magnetic field and interesting effects.
luckily for this post , lightening has nothing to do with ac harmonics

 

All would be raised to the lightning potential (which is relative to ground), but no current would flow unless the assembly had some path to ground. Parasitic capacitance or conductance could provide that path (and usually does).

If you can answer the following, then I'd understand and no need to start a new thread since drjohsmith said it is answered many times already so why start another one with answers here already.

If a circuit board is connected to a long wire say 2 meters wire and they are isolated with no connection to ground/earth. The circuit board and wire is in equipotential. If your hands have super high static and you touch the wire end, the static would flow to the circuit board and damage the ESD sensitive pin, no? Why not?