In Electrical Engineering, What is the difference between ground, earth and neutral?

In AC three-pin plug a cable having three wires is connected. The green one is earth or ground, the red one is live or Phase and the third one is called neutral.

Earth is connected to the body of your gadget and the other two are connected to the main circuit. When you switch on the gadget the circuit is completed and the device starts running.

In electronics usage they are often conflated, though I can't recall the last time I used earth instead of ground. Might be never. For me, an electric ground is a common reference point -- nothing more or less. It doesn't have to be at the Earth potential. In fact, a lot of circuits around the home will have floating grounds in them (all battery toys, for example, and almost everything with a wall wart) where the potential may be quite different than the nearby "earth." Of course "ground" sounds like it might mean "dirt" and so some naturally put the two together and think it must also be "earth." But the idea is separate to me. In my usage, a ground simply means a common reference point around which other voltages are measured and documented and it isn't necessarily, though it may be, the same as a local "earth" potential. An 'earth' is something that is actually spiked into the dirt or built into a foundation (ufer ground, for example, which is just rebar inside the cement structure.) It is a means of tying some specific reference point (probably an electric ground for some circuitry) down close to Earth potential in the nearby area. There are reasons to want to do that and there are reasons to not want to do that. It all depends. A pole power transformer will be grounded into earth at the pole and then again at the house it powers. Those are earth grounds and they help tie various points so that large ground potentials have a hard time building up and causing things like electrolysis and the subsequent corrosion of metals. A common example where that is a very difficult problem is when there is a high current smelting operation nearby. That can cause huge ground potentials over short distances due to the high currents within and around the local area. Weather and lightening can also cause problems that frequent ties into the earth ground help reduce. A decision was made a long time ago, in the US anyway, to tie one side of the AC power grid into the local ground wherever it is distributed. (Allowing a home's transformer power to "float" was considered to be more dangerous than tying one side into the local earth system.) I'd use "earth" advisedly. If you actually mean an earth ground, one that is tied firmly (with less than a few ohms) into the local environment, then I'd use earth ground. But if all you mean is a common reference point in a circuit, I'd avoid that and just use "ground" or "common," instead. The two may be tied together, but it is better to treat them separately and if they are tied then simply note this fact, too.

Neutral- it is a point where the sum of the current meeting at that point is zero. E.g. in three phase star connected winding the neutral is the point where all winding is meeting at a same point obviously at normal operating condition.

Ground- ground and earth both are same term. it may be a reference point for in an electrical circuit from which
other voltages are measured, or a common return path for electric current, or a direct physical connection to the
Earth.

Earthing -it is nothing but the process of connecting all the neutral points of the equipment and non-conductive
exposed part of the metal structure to earth.

https://www.electrikals.com/

In electrical engineering there are sources of electrical energy (power supplies, transformers, batteries, etc.) and sinks of electrical energy or loads (motors, light bulbs, television sets, etc.). An electrical energy source will have two terminals, each connected by an electrical conductor, or wire, to two separate terminals that constitute the electrical load.

The energy source, the two wires, and the load form a closed loop through which an electrical current flows to produce some useful electrical effect. This loop is called a circuit. For reasons that may become clear later, traditionally one of these wires is called the “supply” or “hot” wire and the other is called the “return” or “neutral” or “ground” wire. The neutral wire is usually connected to an earth ground at one point.

Many years ago it was discovered that for some purposes, such as telegraph signaling, the earth could be used as one of the two conductors necessary for a complete electrical circuit. This meant two points far apart could be connected by telegraph using a single wire instead of two wires that would ordinarily be required to complete the circuit. To accomplish this, a conductive rod, usually made of copper-plated steel, would be driven into the ground at each end of the telegraph line. By electrically connecting to these two rods, the earth became a common conductor for the telegraph circuit.

After years of usage, the terms “ground” and “earth” came to mean the same thing to electricians. It also became common practice to extend the “earth conductor” to other electrical applications, including power transmission. Today one can often see a single overhead wire providing high-voltage current to a line of freestanding light poles, the other wire for the lighting circuit being completed by a rod driven into the earth at each pole.

At a utility pole providing electrical service to one or more houses is a cylindrical “pole pig” or transformer. The primary side of this transformer, which may operate at about 7000 volts, often uses the earth as its second, or return, conductor by means of a “grounding rod” driven into the earth next to the pole. A heavy-gauge bare-copper wire stapled to and running up the wooden pole connects the ground rod to one terminal of the primary. A high-voltage feed wire, supplied from a distribution transformer miles away, connects to the other primary terminal as the supply wire for the primary circuit.

The low-voltage secondary side of the “pole pig” is a center-tapped transformer winding providing 120 volts alternating current (VAC) between the center tap and either one of the two ends. Between the two ends, 220 VAC is available for high-current loads such as an electric clothes drier, electric furnace, and electric kitchen range. The conductor attached to the center tap is usually a bare wire called the “neutral” line. It serves as the second, or return, conductor for loads connected between it and either one of the two secondary winding end-terminals.

It is a “building code” requirement in most places that the “neutral” conductor MUST be bonded to an “earth ground” at the service entrance. This is done by connecting a wire in the service entrance panel between the “neutral” and a nearby cold-water pipe exiting from the ground, or if none is available, a suitably prepared “grounding rod” driven into the earth.

At this point, where the “neutral” connects to the grounding point, whether it be a water pipe or a driven rod, there can be no electrical potential between this particular “earth ground” and this particular “neutral” because both are the same point. But not all earth grounds and neutrals are at the same zero potential. It all depends on how current is flowing in the earth and in the neutral wires. The earth and the neutral wires both have finite resistance. If there is current flowing in the earth, there will be a potential difference that is causing that current to flow. The utility companies call these currents “stray currents,” and the potential differences that cause them can be small, medium, large, and sometimes lethal.

There will be potential differences between the “neutral” wire and “ground,” measured at various places along the length of the neutral, because the finite electrical resistance of the neutral, and the net current flowing in the “neutral” from the electrical loads, causes a voltage drop across the length of neutral through which those currents flow. For this reason, one cannot consider the “neutral” to always be at “earth ground” potential except at the one point where it connects to the earth ground. It may be close to ground potential, but there may also be a significant potential, depending on the magnitude of the current flowing in the neutral and the size of the neutral wire.

Which brings us to that “green ground wire” found in modern electrical wiring. This third wire is connected to the service-entrance ground connection, near or at the connection between the “neutral” and earth ground. It should never carry current unless there is an electrical fault condition. If a fault does occur, it is designed to carry enough current to cause a circuit breaker to trip off or a fuse to blow. So, unless a fault does occur, the “green wire ground” should be at zero potential with respect to the earth ground at the service entrance and everywhere a green wire ground is present.

The concepts of ground, earth, and neutral came from the electric power utility industry, but they have also carried over into the design of electronic devices, whether powered from the line or self-powered. There is usually a common point to which all internal potentials are referenced and this point is usually called “ground” or “common.” All return circuit paths converge on this single point. Sometimes there will be more than one “ground” such as “analog ground,” “digital ground,” and/or “power ground.” Usually, but not always, these various “grounds” will connect together at one point, which in turn may be connected to “earth ground.”

Fascinating concept, the Earth as a conductor of electricity. Tesla wasn’t the first or only one to be cognizant of that.

Terminology

If earth is used as a reference a circuit is tied down to 'earth'.
Ground is usually the conductor which is tied down to earth.
Neutral is a conductor with ref voltage 0v this is sometimes tied down to earth.
bit vague but depends whether you are electrical electronic or autoelectrician

Ground: Generally the term ground is used for in the DC ( Direct Current ) system & it denotes the Negative Terminal.

Earth: It the Zero Potential Point. ( For Both AC & DC SYSTEMS). It denotes the Physical Earth which can be taken as a zero reference point for electrical system.

Neutral: It is the Star ( or Common ) Point of the 3 Phase Generator. it is also at Zero Potential.
Usally this Star Point of the Power Generator at the generating station will be connected to Physical earth with thick copper bars.
It is known that resistance of the Earth is very Low. The star point of the transformer or any other devices at distributing point can be connected earth for the getting the Neutral Reference. ( without using any separte conductor.)

Ground and earth are refered to same which is having 0V. Neutral is the common point which is taken from the neutral point of the 3 phase transformer (from "Y or Wye" connection) and in the most cases it will be connected to the earth or ground. Apparantly we expect ground, earth and neutral are same which are connected to common reference point with no potential difference.

Earth - refers to the absolute plane of zero potential to which everything else is referred.

Ground - a low potential that is specific to a certain piece of equipment. This may (or may not) be actually at "earth" potential. For instance, a thyristor drive has both positive and negative terminals ... the negative is sometimes called the "ground" even though is may be at several thousand volts. The positive only refers to the difference between the two (say several thousand plus the drive potential).

Neutral - a point where there is no real potential (voltage) present. This is sometimes connected to a true "earth", sometimes to a "ground", and sometimes left to float freely (particularly in the case where the neutral is a connection that is internal to a rotating machine and is a function of the winding configuration).

They all are at Zero potential.

In DC (direct current). Negative is generally grounded to chassis(attached to the the chassis, Frame). But in recent years some cars started using +ve ground.

In AC(Alternating Current) Uses three wires(now on).

In simplest form, which is single phase, you have Live wire and nutral wire, again ground is call neutral also. But two wires are used all the way to substation and beyond, earthing or grounding is avoided and if done it is for safety rather then carrying current. Grounding is always extra this is the third wire it is green insulation in colour or does not have insulation.

Earth is just another name for Ground or wire that is grounded.

If you look at telephone resent installations in USA, it is the wire that is attached to a bigger rod and the rod is actually, berried in the earth so it is called earth or earthing.