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DISCLAIMER: I am not an electrician or electrical engineer.

Let's say that all I have running in my home is a 10 watt LED light bulb (nothing else). This bulb uses very little of the electricity coming into my home and most of it exits my home on the neutral wire.

Does the electricity company compensate me for this electricity that I return to them, on the neutral wire?

Bort
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UA412
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    "*most of it exits my home on the neutral wire.*", don't you mean *all*? – Harry Svensson Sep 12 '18 at 21:24
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    My understanding is that electricity comes into my home at a 100% state. If my LED light bulb is on, it uses maybe 0.0001%, so 99%+ exists my home on the neutral. I sincerely apologize if I am totally wrong my my concept of how this works, I just need to understand this better. – UA412 Sep 12 '18 at 21:27
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    U are consuming "power" so energy. Are you returning it back? No so no compensation – cm64 Sep 12 '18 at 21:27
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    @UA412 Hmm, yeah, I can see that there's some misconceptions that you have. - Here's some information which might *set something straight*. All current that enters your home, comes in on *one* wire. And then it leaves on *another* wire. It is the same current. So 100% comes in and 100% leaves. The voltage between the two wires are different however, and this is where the *power* comes in to play. You pay for the current × voltage. The electrical company **always** gets current back, you need to form a *loop* for the current to flow. I strongly advice you to use CircuitJS and play around. – Harry Svensson Sep 12 '18 at 21:31
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    You're not trying to 'keep' the current - you're paying for the work the electricity can do: the power. By the way, the water company won't refund the waste, fouled water exiting down the toilet from what the clean water that entered the house, either. – TonyM Sep 12 '18 at 21:43
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    Are you in split-phase North American style, multiphase Euro style, or single-phase Euro-style? – Harper - Reinstate Monica Sep 12 '18 at 22:34
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    add to all this - you are receiving AC - that means that electrons zoom in through the phase and out through the neutral and then back the other way again 50/60 times a second on average you get to keep none of them. As others have pointed out it's the work that they do in this process (the light and heat they generate) as they pass through that you pay for - it's why you pay for kW/h (units of power per hour) rather than say electrons per hour – Taniwha Sep 13 '18 at 09:45
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    See also https://electronics.stackexchange.com/q/233851/4512. – Olin Lathrop Sep 13 '18 at 10:59
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    @HarrySvensson, in AC, virtually [none of the electrons will leave his home](https://www.quora.com/In-a-typical-AC-circuit-how-far-does-each-electron-travel-along-the-wire-in-one-direction-before-the-polarity-is-reversed-in-a-single-alternating-cycle) – crobar Sep 13 '18 at 13:05
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    @crobar There are 100 other things that are also wrong with what I said. It doesn't matter where I start, anything I say will be wrong, but it will be a stepping stone for OP. - To respond to your comment properly I would have to write 10 comments to explain what's actually happening, I don't have time for that. - So my response will be. "Ok". – Harry Svensson Sep 13 '18 at 13:09
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    The electrons don't move much. What does move, very quickly, is the EM field in the space between the wires and coralled by the massive ocean of mobile charges in the metallic conductors. – Martin James Sep 13 '18 at 19:19
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    Note that there exist such things as *reactive loads,* where energy flowing back from the consumer to the supplier has to be accounted for. This is considered detrimental due to extra losses in power lines. Only relevant for industrial-sized consumers though. – Roman Odaisky Sep 13 '18 at 22:04

6 Answers6

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You are not really paying for the electrons that move in the wire, you pay for the force that moves them. It is like cutting a board with a hand saw. You push an pull it to cut the wood using the same teeth for each stroke. The electric company pushes and pulls the electrons and the moving electrons do useful things like provide light. You furnish all of the materials including the electrons in your wires. The electric company sells you energy in the form of moving electrons.

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    Adding onto this - the "force" is the voltage. Just think about the voltage. The active wire has 240V (or whatever, depending on your country). Your lightbulb takes all 240V, and on the other side of the lightbulb your neutral wire is 0V (that is neutral by definition). So you are returning 0V to them - i.e. no potential, therefore no power, therefore nothing. – DSWG Sep 12 '18 at 23:38
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    Might I add that this "shuffling" only applies to companies that use AC power. Those that use DC you get a slow creep of electrons around the circuit (drift speed is surprisingly slow) but the argument that you pay for the EMF is definitely still valid. –  Sep 13 '18 at 00:04
  • I thought the electric field was the thing doing the work, not the electrons – Voltage Spike Sep 13 '18 at 00:50
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    @laptop2d electric field (voltage) performs no work. Moving electrons (amperes) perform no work. Only the two together (volts * amps) can supply an energy-flow. (The electron-flow supplies the magnetism side of the EM flow.) Imagine pure current as like a frictionless spinning drive-belt, while pure voltage is like a stalled drive-belt under tension. To communicate some actual horsepower, the drive belt must be moving, but also under tension (a force against the driven load.) Utility companies sell a pumping service, supplying flow and pressure, billing us for total energy per month. – wbeaty Sep 13 '18 at 02:42
  • But you can do work with the electron drift being near zero (mm/s) on an AC line – Voltage Spike Sep 13 '18 at 03:12
  • It's like sound waves. The sound moves faster than the air, which is the medium. – CJ Dennis Sep 14 '18 at 00:37
  • @Persistence isn't that *all* modern power companies? There are niche scenarios where you might have DC mains (e.g. inverterless solar?) but they're not common especially for consumers. And grandfathered systems which I understand are all gone by now. – user253751 Sep 14 '18 at 03:54
  • I was under the impression Argentina has DC mains (quick google search) but I could be wrong –  Sep 14 '18 at 03:58
  • @Persistence until recently an efficient power distribution network based on DC would be impractical expensive. Transformers were too critical for low loss transmission. – Aron Sep 14 '18 at 10:41
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There isn't really any such thing as "electricity". The word "electricity" simply refers to the transmission of electrical energy, by using the motion of electrical charge.

Electrical energy and electrical charge are not the same thing. In particular, electrical charge is not scarce or valuable; all matter contains electric charge, and, in fact, it all contains roughly the same amount of electric charge, weight for weight. A charged battery doesn't even contain any more electric charge than a dead battery does!

From the perspective of electric charge, here's what happens when you have a light bulb plugged in, and nothing else:

Electric charge goes into your house, and into the light bulb via the hot wire. At the same time, the same amount of electric charge goes out of the light bulb via the neutral wire and out of your house. Then this process reverses direction. Electric charge goes into your house, and into the light bulb via the neutral wire. At the same time, the same amount of electric charge goes out of the light bulb via the hot wire and out of your house. The process reverses direction again, tens of times per second.

So, the electric charge pretty much just wiggles in place. The electric company doesn't bill you for the electric charge; like I said, it's not scarce or valuable.

But why is all of this wiggling useful? How does it accomplish anything?

The answer is, the electric charge doesn't simply glide effortlessly through your light bulb. The electric company forcefully pushes charge in through the hot wire and forcefully pulls charge out through the neutral wire. Then the process reverses direction; the electric company forcefully pushes charge in through the neutral wire and forcefully pulls it out through the hot wire.

All of this forceful pushing and pulling requires a lot of "effort" by the power company—which is to say, electrical energy! Meanwhile, your light bulb is able to harness this forceful pushing and pulling and turn it into light.

So, your electric company doesn't charge you for the mere motion of charge; what they charge you for is all that "effort" (energy) that they're exerting in order to move it around. And all that effort is (normally) a one-way flow; your house never (normally) exerts its own effort in order to send electrical energy back to the power company.

All of this is analogous to the chain on a bicycle. When you pedal a bicycle, you're transmitting mechanical energy by using the motion of "mechanical charges" (the links in the bicycle chain). You're not transmitting chain links from the pedals to the wheels; you're transmitting energy to from the pedals to the wheels by using the chain links (by forcefully pulling on them).

So, your question can be interpreted in two ways:

Does the electricity company compensate me for this electrical charge that I return to them?

No, because electrical charge is available everywhere for free, and the electric company isn't billing you based on the charge anyway.

Does the electricity company compensate me for this electrical energy that I return to them?

No, because you're not returning any electrical energy to them; you're only returning electrical charge.

HandyHowie
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Cassie Swett
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    Very nice and explanatory answer! – Reverse Engineered Sep 13 '18 at 05:55
  • If one thinks of electrons as LP (propane) tanks, the act of using power involves receiving tanks and--very soon thereafter--returning them with slightly less gas. One is generally charged not for the tanks, nor in most cases even for the rate at which one exchanges them, but rather based upon the difference between the amount of gas received and the amount of gas returned. – supercat Sep 13 '18 at 17:20
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    @supercat I dunno how I feel about that analogy, though. The "amount of gas in each tank" corresponds to the electric potential, right? But if I have a long wire, I can change the electric potential of the entire wire in a fraction of a second without moving the electric charge any significant amount; whereas if I have a long line of propane tanks, there's no way I can remotely fill the distant tanks. Also, propane tanks can be completely emptied out, whereas you can't "empty out" the electric charge in a wire. – Cassie Swett Sep 13 '18 at 18:30
  • @TannerSwett: Yeah, I know the analogy isn't very good regarding the mechanism, since it fails to allow for the possibility of cans exchanging gas with their neighbors, but I couldn't think of anything else that handles the concept that one is continuously giving and receiving electrons, but the ones that are returned will have less energy than they did when they were received, and what one is billed for is the energy one has extracted from them. – supercat Sep 13 '18 at 18:57
  • @TannerSwett: Though I was just thinking that perhaps the right model is not that one takes something from the electricity and gets billed for that, but rather one pays the electric company to build up pressure in one's lines in alternating directions 60 times per second, and is charged based upon how much energy is required to do that. – supercat Sep 13 '18 at 19:03
  • Great answer. I'd just add that many modern devices do in fact return electrical energy -- LED lights driven by capacitor droppers and imperfectly compensated motors among other things. You are credited for the returned energy. – David Schwartz Sep 13 '18 at 19:43
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The electricity which comes into your home and you are billed for is not the electrons in the wire (which don't actually enter and leave, they just move backwards and forwards since it is alternating current that is being supplied). And the same quantity of electrons would be moving, whether you are running a single LED bulb or charging an electric vehicle.

What you are paying for is the force moving those electrons. In the case of the LED bulb a small quantity of that force is being converted into light.

Imagine that you have a small workshop run by water power (perhaps in an Amish community.) Water comes in through a pipe, turns a waterwheel which powers the machinery, and exits through another pipe. The "power company" isn't going to bill you for the water, because it is just a carrier for the power, and you are returning 100% of it to them in any case. They will bill you for the motive force that is pushing the water through the pipe (and turning your waterwheel).

Batperson
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  • As I have added to other answers, not every country utilises ad AC power grid. Although your point still stands. –  Sep 13 '18 at 00:05
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Your electrical devices allow a certain amount of current to flow through them. Lower powered devices draw proportionally less current than high powered devices. In simple electrical circuits the device's "resistance" determines how much current flows.

What comes in on the live wire returns on the neutral wire.

You pay for what you use.

A little theory:

  • The voltage supply to your house is constant 230 V in Europe or 120 V in North America, for example.
  • Each device, when on, consumes power at a certain rate. Power (watts, W) can be calculated by voltage (volts, V) x current (amps, A). Most devices will have at least two of these parameters on the label. You can calculate the third from that.
  • When you switch on your 10 W light bulb only 10 W is drawn from the mains even though the whole national grid is available.
  • You are billed in kilowatt-hours (kWh). If you leave your 10 W lamp on for 100 h you will consume 1000 Wh = 1 kWh. This will cost in the region of €0.15 / $0.15.

... so the meter compares how much electricity goes in to my home with how much exits, and essentially logs the difference (which I have to pay for)?

No. What goes in goes out (returning to the source) so there is no need to measure it twice. Just measure what comes in.

Transistor
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  • Ok, so the meter compares how much electricity goes in to my home with how much exits, and essentially logs the difference (which I have to pay for)? – UA412 Sep 12 '18 at 21:28
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    Sorry UA412, it isn't that simple. There is no well-defined concept of 'electricity' as you use it. As T says, all electrical current that enters your house als leaves your house. – Wouter van Ooijen Sep 12 '18 at 21:32
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    @UA: See the update. – Transistor Sep 12 '18 at 21:34
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    @UA412 I *believe* electricity is an umbrella term for current and voltage. It's okay to be vague and say *electricity* when you are talking about either in some public newspaper, but right now, on this site, you have to learn that there is a difference between them. It's time to learn. Time to be less vague. – Harry Svensson Sep 12 '18 at 22:09
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    Something that does track current in vs current out is an RCD - a safety device, since if there is a mismatch it means current is probably flowing in a human. – pjc50 Sep 12 '18 at 22:13
  • "Constant 230V" is a rather confusing description of an AC supply, IMO. But I accept you have to keep things simple at first! – alephzero Sep 13 '18 at 00:39
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    @UA412 you don't pay for electricity, you pay for electromagnetic energy. The electrons flow in a complete circle, like an endless drive belt. Utility companies don't sell "amount of drive belt," instead they sell "amount of energy." (In physics class they finally tell us that the electric company takes back every electron that they send out: wiggling equally back and forth as AC, with none being used up.) – wbeaty Sep 13 '18 at 02:50
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As a first suggestion, please forget about moving electrons.

The most important difference is voltage versus current and idealise the notion of power consumption to having no line loss.

Voltage is static, current flows.

Voltage is always there, no matter if there is any consuming device - e.g. your light bulb. Current flows as soon as there is a consuming device switched on.

Current together with voltage is power.

What you pay for is power (in Watts or Kilowatts) over time (in Seconds or Hours). The more power and the longer your devices draw, the more you pay.

To summarise: You do not return anything to your electricity provider if no device is switched on, because there is no current flowing anywhere, and also no power consumed.

rexkogitans
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    Even _if_ you are an electrical engineer, you should forget about moving electrons. That's something only a physicist or chemist should deal with. – pipe Sep 13 '18 at 08:50
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It's useful to think of electricity like water. Your house is probably connected to a public water system, which supplies you with water.

If you do not use water by turning on a tap or something, does any water leave your house? Of course it doesn't. Only the water which you use leaves the house through the sewers. Also, no more water than what you use enters the house. But even if you don't use water, the pipes have pressure so you CAN use it.

It is the same with electricity. If you have nothing powered on, no electricity enters your house, and nothing leaves. If you turn on a 10-watt light, 10 watts of electricity enters your house. It then leaves again. But even if you don't use any electricity, you still have voltage in your sockets. This voltage is equivalent to the water pressure. If you connect something, the voltage will create a current (equivalent to water flow) flowing to your device and powering it.

The electricity company bills you by measuring how much power enters your house, or, equivalently, how much leaves your house.

If the amount entering and leaving ever differ, you have a potentially fatal grounding fault. You have a fuse protecting you from that.

mike65535
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Suppen
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    Welcome to SE! Please watch/research your terminology (power/voltage/current) to avoid misconceptions. No need to include the assumptions about ground faults, as well as the presence of any possible protection circuitry. – Chris Knudsen Sep 13 '18 at 11:52
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    As a side note, fuse won't protect you if some of the current does not leave though neutral (fuses are there to protect the instalation from fire, and will trigger when line and neutral are shorted). To protect from current taking other exits then neutral, you need so-called Residual Current Device (also known as `RCD`, `GFCI`, `FID`etc) – Matija Nalis Sep 13 '18 at 23:46