I know that electricity doesn’t just dissolve in the ground, it must return to the power source. But once the electricity is in the grounding device, how does it find its way back to the substation if it can be relatively far away?
Edit: I know ground isn’t used in normal working mode and where I live there’s no grounding in sockets.
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Electricity doesn’t simply flow from source through circuit back to source. Electricity is defined by a potential difference. Electricity flows from high potential to low potential. Earth is simply the lowest potential available. It gives a reference as to what some voltage even means, because this voltage is in reference to earth.
I recommend looking up earthing systems, because this gives a rather good idea what earth ground is actually used for and why we ground circuits.
It’s not that electricity is flowing through the ground (though it will in an emergency)
So in a 3 prong plug, that round ground is for safety: if there’s an accident or short, it will discharge through it into ground hopfully popping a breaker.
The MAIN “hole” in the hose though is the neutral. You can tell it’s basically the same as a ground because if you open up an electrical box, neutrals and grounds attach to the same bar.
So there isn’t supposed to be electricity actively flowing along that neutral, but it serves as a highway for electricity to in theory flow to the ground. In practice though electrical components that consume electricity use it up before the power gets to the neutral.
“it must return to the power source”
This is incorrect, electricity is simply seeking its path to ground, or the place of least electrical charge/resistance. Otherwise, electricity would be flowing out of your house as well as in (ok for people with solar panels this CAN happen)
The source is also grounded, in North American residential this would be the centre tap of the supply transformer. High current to ground on ground faults only exists because the source itself is grounded. Those currents flow through the earth back to the source.
If the source were not grounded in any way, a single ground fault would not cause those high currents.
So if you break electricity into AC snd DC it becomes more clear.
DC is just like water flowing through a hose in a loop. If you picture a side shot of that hose and buried some of the hose in the ground thats DC. And for clarity the underground parts of the hose leak into the earth but its a smart hose so the in and out pressure stay the same.
AC is also a hose in a loop but the direction of the water in the hose is pumped in one direction and then the other. This means you don’t need the buried section because there is coherence in the bidirectional flow of the water. But if you don’t trust that the hose enough you can add an attachment that will direct any leaks into the ground.
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At least with AC the electricity does kinda dissolve in the Earth. The area around the grounding rod acts as a capacitor that is charging and discharging as the AC waves go. You could split the planet in half and connect each side of the circuit to each half and it would still work.
In the water analogy imagine a pipe that is closed on both ends and you try to push the water to flow forwards and backwards – it won’t. Now connect some big reservoir on each end of the pipe – now you can make it flow back and forth. It can be the same reservoir on both ends or two different ones, doesn’t matter.
Electricity is a lot like a water flow where the ocean would be your ground and your voltage would be a height difference.
If you have a lake above water level and it is connected to the ocean, the water will flow from the lake to the ocean.
For the water to get back in the lake you would have to pump it up which requires work. For electricity you would use a generator.
So firstly, electricity doesn’t need to flow back to its source! It goes from high to low. On a battery, it looks like it flows back to the source, but thats because the battery has a high and a low side. You’ll probably have seen the + and – signs on the side of the battery? That’s what those are. With a substation, its not recycling electricity, the substation is constantly getting new electricity from the power plant.
You can kind of think of electricity as pressure. Typically water pressure is used as the example, but when we talk about grounding I think its easier to use air pressure.
Imagine a battery with just a + side. Its got a certain limited electrical potential, and it needs a – side. In our example its like a balloon, filled with air at a higher pressure than the atmosphere around it, and that air wants to get out.
When we want that battery to power something, we use the difference in the electrical charge to move electrons and generate electricity. With our balloon, we use the air pressure in the balloon to make things happen.
So, what happens if you don’t have any difference? What if the balloon was hooked up to a tank with the same air pressure inside?
Well, nothing happens. There’s no difference, and you need that difference in pressure to make the air move and do work. The same thing is true for electricity. If we have two sources both at the same electrical charge, then no current flows, no work gets done, no lights turn on.
So how do we make sure we always have a difference? The simplest answer is that we attach our balloon to a hose that, after flowing through some machinery to do work, leads to the outside air. We now have a consistent flow from source to outside air regardless of how high (or low) the pressure in the balloon is! The same thing applies to electricity, except instead of using just the atmosphere, we use the whole Earth itself.
Basically, electricity is all about a difference between two electric charges. We can (and do) make these differences ourselves, but thats work that a lot of the time we don’t need to do.
For the electricity that you use in your house, it flows from the power line, through your appliances and lights and computers, and then out into the earth.
So where does it go from there? Well, the earth is a pretty huge reservoir of electric charges. Itd be like taking water from your tap and pouring it into the ocean. Is there more water there than before? Sure, yeah. Does it make a difference to the ocean? No, not really.
On the power plug for home devices, you’ll find 3 prongs:
– A Hot/Live that supplies power
– A neutral that completes the circuit back to the grid/substation
– A ground for use in emergencies; eg. You want the chassis of your PC to be grounded, because if a live wire ever accidentally touches it and it isn’t grounded you could be shocked with 10amps.
What you are describing with no neutral completion wire is [SWER](https://en.wikipedia.org/wiki/Single-wire_earth_return). Most city wiring will not use a ground return as there is more power than in a rural system and can cause issues with [Stray Voltage](https://en.wikipedia.org/wiki/Stray_voltage)
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