Just to expand on the comments above, It is called Neutral because it is the NEUTRAL point of a three phase STAR connected Alternator set.
For safety, the UK also connect this neutral point to Earth at the source of the energy. This is expanded in some supply types to give what is called Multiple Earth Points.
Neutral and Earth are NOT the same, as I have said in a different thread, the Earth connection of the Neutral point is designed to reduce the potential difference of this point to as near to that of the Earth as possible, in reality this can be anywhere between 0 and 49V. If it hits 50V RCD's will disconnect the supply.
If the Alternator and supply infra-structure where not connected to earth in this way, then the potential difference between the Neutral conductor and Earth would be the same as the Phase to Neutral potential difference, ie, 230V.
From this statement you will see that connecting your neutral to Earth will create an inherently dangerous situation.
I seriously hope this is just a theory question, there is nothing to be gained by this action except putting lives at risk.
There are actually THREE reasons why a Neutral Earth connection will trip an RCD. The most common known has been stated above, however there are two other ways in which an RCD can detect a fault and disconnect the supply.
Firstly, the toroid of soft Iron that coils are wrapped around for the Phase and Neutral conductors are not alone, the earth also has such a coil. This coil will instantly detect, via magnetic effects, any voltage above 50Vac/dc on the Earth line, it does this via a magnetometer coil mounted inside the torus of the RCD.
Secondly, the RCD sensing coil will "know" that the supply is off or on, the electronics know the potential difference between the Neutral and true earth. The electronics constantly monitor the PD between the two, should that suddenly change to zero within 0.02 seconds, the RCD will disconnect the supply.
An RCD is a clever bit of kit, the ones with little white tails of wire connected to them are DC sensing RCD's, these constantly monitor the Potential of the earth connection and should it change rapidly or increase above a factory set level for a given current rating, then it will disconnect the supply.
It is for this reason that putting any RCD, but especially the DC sensing type, on any circuit containing large inductive loads or electronic equipment is likely to cause nuisance tripping of the device as both are notorious for "backfeeding" a dc voltage onto the Earth of the circuit, normally via the body of the machine or piece of equipment.
To answer the other question, PSSC, also called PSC or PSCC is the Prospective Short Circuit Current
Simply stated, this is the maximum amount of current that will flow through a circuit in the event of a short circuit before the installed protective device will operate and disconnect the supply.
For the supply coming into your house this can be in the 10kA to 20kA range, depending on how the local supply grid is connected up and the ratinf of the nearest transformer substation that has protective devices installed. It is very unlikley you would cause one of these to operate in the event of a fault, unless you damaged the cable before your service head, effectively between your supply and the transformer. Even then it is unlikely they will operate. They have surge capabilities which for a split second can handle currents many times their nominal rating, in this time the current flowing would vapourise any metals it past through and effectively disconnect the short from the circuit.
Nah, only joking.
