I have a very basic understanding of how electricity flows, so apologies in advanced if this is a dumb question. As far as I understand, electricity comes into my house and goes to my devices, and then is returned through the neutral wire to my panel, where it goes to ground.
Why can’t that energy returning from my devices through neutral be used to continue providing power instead of just going to ground?
What I think is the answer (please correct me if I’m wrong): in order for the current to even flow, the circuit needs a path to ground
In: Physics
There’s two parts to electricity – voltage and current. Voltage is the energy carried by each electron, and current is the number of electrons moving.
The “loop” of electricity is some number of amps – some number of electrons. They move between the high voltage to the low voltage, delivering that energy as they go.
To harness energy from the current that leaves your home, you’d need voltage. It has none. The electrons are spent. They need to pass through something that refills their energy – raises their voltage – before they are again useful.
I’m sure someone with a better grasp of physics can poke lots of holes in this analogy, but you can *kind of* think of electricity in a closed circuit like water flowing downhill. (or down a pipe from an elevated tank)
Once water has collected at the bottom, it has no more potential energy, you’d need to pump it back up. (or wait for more rain, or whatever)
Similarly, if you just let electricity flow through something without generating more, the electric potential difference (voltage) will eventually drop to nothing.
(in this analogy, voltage is comparable to how high up your water-filled tank (or the hill the water is flowing from) is, or how high the pressure is, and current is the volume of water flowing)
An analogy is a bicycle chain. The power plant is your pedals and your house/devices are the wheel.
When you pedal your bicycle, an individual link in the chain will go to the wheel and then come back. Why can’t we just “reuse” the motion in the links going back to the pedals?
The answer is that is more accurate to think of the chain as a connector between your pedals and the wheels. The links all connect to each other to transfer that force.
Likewise, the wires connect your devices to the power plant, and all the individual electrons push on each other to transfer that power.
You have a fundamental misunderstanding of how the electrical system works. Electricity doesn’t flow from the street to your house, through a circuit, and then into the ground. It flows from the street, through a circuit and then back out to the street.
The ground connection is basically just to provide a safe path for electricity to take back to the panel if something short circuits somewhere, once that current gets back to the panel it will then flow back out to the street and not into the ground. That’s a bit of an over simplification but for the sake of this explanation it’s good enough.
So basically electricity IS reused after leaving your house and it was just a misunderstanding about how the electrical system works that lead you to thinking it wasn’t.
The energy isn’t really returned to ground through the neutral wire. It didn’t come from there in the first place. Ground does provide a difference in potential that allows current to flow through your devices, but all of the energy that flows is converted to something. Motion, heat, light, etc. That’s why a light bulb consumes less than an AC unit- it just doesn’t need as much. If you turn everything off, the difference in potential is still there, but nothing flows, because nothing is being consumed or converted to other types of energy.
The hose analogy works here. It comes in with energy (think the pressure from your tap) and leaves via the sewer.
You can reuse it, but you need a pump, it’s not going to shoot out of the drain and flush your toilet (if it does you have big problems).
Likewise the electrons are flowing, but you’re using the energy. That bit leaving doesn’t have the energy
It’s already lost it’s potential energy.
Let’s just assume is 120V DC power (it’s not)
It comes in at 120V, meaning each electron has 120 eV (electron volts) of energy. That’s 1.92×10^-14 J
It flows through the device, giving us thay potential energy, meaning it now is at 0V (ground it always 0V) and each electron has 0 eV of potential energy (0 J)
How do you do work with no energy?
It reality, we have 120V AC (in the US), so the generators are basically pushing and pulling the electricity back and force, and the electrons on the other side (between you and ground) are basically just a loose end. Without those, it’s like the generator is trying to pull a rope attached to a wall, but with ground, there’s just more rope to pull on
It doesn’t flow out of your house in the manner you think.
Think of getting power like there is a long belt between you and the power company. Literally, charged particles move down the wire, through your appliance, then back down the other wire to the power company and then back again one giant loop. This ‘belt’ of power drives electric devices, just like a physical belt would drive physical devices. If you don’t send the ‘belt’ back the power company has no belt to send you.
You can think of a power outlet as a long moving belt of power and when you plug your device into it, you are ‘attaching’ your machine to that belt to power it.
The way electricity works means that you only take as much power as you are currently using from the main line in the street.
Yes, the voltage goes from 120v (or 220/230/240v depending where you live) to zero but that’s only the voltage. If you’re comparing this to water, the voltage is like the starting height but you can’t just use part of it because all your appliances need the full height to work properly.
The other part is the current which is like the amount of water you are using. You can have a water pipe from the top of the hill to the bottom but that only tells you how much pressure you get at the bottom. The current is how much water you’re actually letting out the tap at the bottom. If you’re only running a phone charger then your tap is only open a tiny bit so you don’t use much power
So this is not a scientific explanation. It’s a guy drinking beer on a Friday night.
Electricity doesn’t “flow” in the classical manner you think.
Electricity has the capacity to do work: it is a potential.
The wires are guides for that potential. There is no “return” path, the electricity (potential) does not flow back to the source, or anywhere out of your house.
It is either consumed (used to perform work, and dissapated as heat energy) or not.
The power lines provide a consistent differential of potential. A 120V + GND reference will provide max ~120V, and a 120V and out of phase 120V will provide a max ~240V potential difference between them.
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