P Conductor E Conductor->PE Conductor
I would think Wiki's definition  would be adequate for you.


  An earth ground connection of the exposed conductive parts of electrical equipment helps protect from electric shock by keeping the exposed conductive surface of connected devices close to earth potential, when a failure of electrical insulation occurs. When a fault occurs, current flows from the power system to earth. The current may be high enough to operate the over current protection fuse or circuit breaker, which will then interrupt the circuit. To ensure the voltage on exposed surfaces is not too high, the impedance (resistance) of the connection to earth must be kept low relative to the normal circuit impedance.


"PE" in Europe is referred to as "bonding" in the Canadian Electrical Code (CEC)  and the only place where the term "ground" is used is for the cable that goes from the main service neutral to the ground (earthing) electrodes.

Most electricians and engineers still refer to the "ground" wire that runs in each cable, in each cable tray etc, however, the CEC clearly refers to this as a "bond" conductor.

In Electronics we learn by experience that all grounds are simply 0V for convenience  even if they are floating or have noise on them until they are earth bonded or earth grounded and even then noise can get in/out.

With submarine cables there is more than 1kV difference between "Mother Earth " in EU and North America.  The magnetic currents also induce large currents if not protected.

A HV transmission tower earthing typically has about 100 ohms in typical soil with much lower possible, but in global average, it is in this ballpark.  It is much lower for distribution to service entrance.