With mains systems there are two common systems regarding the earthing arrangements.
M.E.N. system, Used in the UK and it's colonies like New Zealand, Australia etc.
In this system the neutral and earth cables are linked at the supply LV (240/415Volts ) transformer secondary, and earthed to the earth bank, they are linked along the cable en-route in distribtution pillars and to the local earth bank by the pillar, and at the end user at the mains switch board and to the earth pin(s).
When close near the N/E link there should be no voltage present between the E and N, or from E at switch board to the earth pin(bank).
The earth wire in the MEN case always carries a current, although it is less then the neutral current because the ground resistance usually will limit this current flow and the bulk of return current is carried by the neutral.
In case of a high resistance or broken neutral caused by a cable fault, a voltage may be present at the neutral and earth, to an independant earth away from the earth pin from the end user.
A higher (270 V) or lower (130 V) than normal voltage may be present , depending upon the balancing of the 3 phases supplying the end user.
In continental Europe a separate earth is used and is not linked to the neutral.
A low voltage may be present between the earth pin at the switchboard and the neutral from the supply, depending upon the loading of the system.
Of cause local POCO's may have some non standard systems in use as well.