What is the difference between earth, neutral and ground as electrical terminologies?

Question

What is the difference between earth, neutral and ground as electrical terminologies?

Answer 1

As mentioned earth and ground are the same terms used in different countries. The earth (ground) conductor is electrically connected to the earth so that anything it is connected to, cannot become live. There will be be some kind of local regulation determining the maximum resistance that is allowed where the connection is made to ground (rod, mat etc)

The neutral is one connection of the supply transformer that is also connected to earth. It is not a return path as such because ac is changing direction. The reason it is connected to earth is for safety. It means that a fault (to earth) of the live conductor will cause the overcurrent device (fuse or breaker) to operate and trip the power.

There are systems that do not connect one side of the supply transformer to earth (no neutral). They still function just the same as an earthed system. This is more common in military or medical and requires some form of sensing circuit to detect faults but the fault gives an alarm rather than a trip so that power remains until an outage can be planned to find the fault.

Answer 2

Earth and ground are at  the same potential.  A ground or earth connection provides a means to complete a circuit if a hard-wired one does not exist.  For example, if an appliance has a short between one of the supply wires and it touches the metal case, it would short out to ground (and would blow the fuse or trip the breaker) as most appliances have a ground wire attached to the appliance casing.  

A ground connection is obtained by connecting a wire to a metal stake or to a metal underground water pipe, e.g. where a water pipe enters a house.

A neutral is a supply wire that is connected to ground at the electrical service panel.  By doing this, only one of the supply wires is at high potential (e.g. at 120 volts AC in Canada & the US).  This practice makes wiring safer (only one "hot" wire instead of two.) The neutral is close to ground potential and if you put a volt meter on it to ground, you may measure a couple of volts.

The neutral is also considered in some areas as the center connection of a star-configured transformer; it is a common point for each of the 3 phases.

Answer 3

Earth (UK) and ground (US) are the same, and they are a protection in case a wire comes loose in your electronics, it should short to ground (and hopefully not electrocute you.)  Neutral is the return path for your live/hot wire to complete the circuit.