I understand why you get harmed if you’re grounded, you’re becoming part of the wire and the electricity is going from you to the earth. what I dont understand is, why the electricity doesnt harm you when youre not touching the ground, isnt it going through you either way? how does it not affect your body?
In: Physics
If you take a short piece of hose and bend it so that the two ends just touch on top of water in a bucket, why doesn’t water run through the hose? In a simple model of the universe, it is because the water would be moving against the gravitational field without an external force to not only cancel out gravity, but to accelerate it up. Or explained in a different way, up higher, things have more gravitational potential energy. Left free to move, things will go to a location or state with lower potential. So when left to move freely, water flows downhill.
In order for electrons to move through a circuit, there has to be a source of electromagnetic potential. It gives the push to the electrons so they will move. As they move, they carry energy, which is what does the work when we plug stuff in. If you are not grounded, you are basically wrapped in a pretty decent insulator, air. The electrons in the wires are feeling an alternating push while in the transmission line due to big magnets being rotated in a generator somewhere. The areas of high potential and low potential are moving back and forth along the length of the wire. When you touch the wire and are grounded, basically you are an extra path the electrons could take, but both your hands are at the same potential. There is an area of lower potential for those electrons to get to, and it isn’t through you. Just like the water in the bucket has an area of lower potential to get to, but not through the hose that goes from the surface of the water into the air and back down.
Edit to add: when you touch a transmission line when grounded, then the electricity will flow through you, because being grounded means you are connected to the neutral Earth. 0 electric potential, more or less. So you become the conduit for all the electrons that are feeling really squished together (high potential, high voltage) and the Earth, where they can be at the lowest potential possible. Like if you cut a hole in the bucket and affix the hose to the side, the water will travel out as long as the end of the hose is below the water level. Bringing the and of the hose above the water level is like disconnecting a ground. The water and the electrons, respectively, will stop flowing.
> isnt it going through you either way?
not really. current follows “the path of least resistance”. you are a really bad conductor, but 6 feet through you to reach the ground is less total resistance than the miles of wire back to the substation.
if you aren’t touching the ground, you’re just a few feet of really high resistance to get 6 feet closer to the substation, so the current keeps going through the wire, instead.
Electricity always ends up where it started from (technically no but for ELI5 yes) so imagine a race track and the race car is Electricity. It starts at the start line (the power generator) then travels the track (wires) then back to the start line (back to the negative/ground of the generator). If you were standing in the track the car would hit you on its way around back to the finish line (Electricity would shock you). Now imagine a bulldozer rips up a big section of race track. You are standing at the edge of the track looking at a big hole in the ground. The race car can’t continue going around so it comes to a stop, you don’t get run over (you don’t get shocked).
Imagine a dam which is holding back water at a certain height. Now imagine two different additions to the dam: the first is an extension to the dam (imagine like a U-shaped section built onto the outer wall) that’s the same height as the rest of the dam. If they then open the extension up to the reservoir, a bit of water will obviously fill the extension but there won’t be any sustained flow, as all the water does is essentially shift a bit.
The second addition is another extension, but now the wall is much lower than the original dam height. If they open that extension up to the reservoir, the water will end up crashing down and overflowing the shorter wall, leading to a sustained flow until either the reservoir is closed off again or the water equalizes in height on either side.
The second example is the equivalent of grabbing a power line while grounded. The Earth can basically be thought of as having an electric potential of 0 Volts, while the power line has a much much higher potential, similarly to a tall dam that’s holding back a huge amount of water with a ton of potential energy. If you grab the line while not connected to the Earth, you provide a small place where the electrons rush in initially, but as you’re not connected to anywhere the electrons can escape to easily, you eventually equalize with the potential in the wire and the flow stops very quickly. Your body would now be at the same voltage as the line and there would be no net “pressure” that would cause the electrons to move through you, just the pressure of the resistance of the air/your rubber shoes equaling the pressure coming from the nearby transformer/substation.
But when you’re grounded, your body will now have a potential difference, where it’s 0 Volts at your feet due to the Earth being at 0 volts and however many hundreds of volts at your hand or wherever it’s touching, and like the dam that’s mostly a very high wall but is now open to a section of low wall, the electrons will want to move to the lower potential and are able to maintain a sustained flow until the connection is broken or the voltages equalize, neither of which would probably happen before you take massive damage through the path of the flow.
Electricity is a flow of electrons. If you aren’t grounded, the electricity doesn’t have a path to flow through your body. No electrical flow, no shock.
That being said, you CAN still be mildly shocked by a live wire even if you aren’t grounded. AC or alternating current switches polarity 60 times per second. Your body has sufficient capacitance that AC current will flow in and out of your body enough to cause a shock.
Although it isn’t perfect comparison a lot of the rules for electricity also apply to water flow (like series and parallel resistance laws) where Pressure is the analog for voltage.
So as a simple explanation, take a water bottle and open it, now close it flip it upside down, and open it again.
When it is facing up there is no path where the water can lower it’s energy so it doesn’t flow, when it is upside down, the water flows out because there is a path where it can lower it’s energy.
Also electricity doesn’t really take the path of least resistance, it takes all paths wieghted by the resistance of each path.
Basically as long as there is no voltage difference electricity won’t flow. Which is why a switch works
It’s like me asking you to draw a circle with a pen but you only have enough ink to draw a half circle.
An electrical circuit is a circle much like a horse race around a track. The circuit must be complete in order to work. If there’s no ground or neutral return path then the circuit can’t be completed.
Watch a slow motion lightning strike. When it hits the ground, the other branches disappear.
You are one of those smaller fork-offs. Until there’s a path for it to go, it’s a much smaller residual bit looking for somewhere to go.
If you’re not grounded, i.e. providing a path, electrically your a dead end. You would be the equivalent of turning into a cul-de-sac on your way to work.
Your body is already full of electricity (and ghosts for all I know, I’m drunk), so if you don’t give it a direction to flow by being grounded then it won’t flow (the lazy bugger). The flow is what hurts you by cooking parts on the way through
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