Query regarding PME

[harrymonkfish]

Hi all.

There is one fundamental thing I don't understand about PME supplies.

If the line conductor comes into a system and the neutral goes out, then in a balanced system the current should be the same in both conductors right?

So in a PME system the earthing conductor is connected to the live neutral conductor.

Why then is the earthing conductor not live as well and hence all othel conductors connected to it?

Thanks for your time.

Regards
Harry

 

[Des 56]

The neutral conductor carries the same current level as the Phase conductor in a balanced system

The phase conductor is at 230 volts with regard to true earth,because the neutral of the supply transformer is earthed at the star point of the transformer

Because the neutral is earthed at the star point,then its potential difference to true earth may be just a couple of volts
So yes the earth system in an installation and everything connected to it are at that low potential

The suppliers spike the neutral conductor at various points to make sure that it maintains that low potential
Hence the protective multiple earthing

Because of the possibility of that neutral/true earth potential rising due to external problems
PME should be assessed with regard to exporting it to garages and sheds etc

 

[sivoodoo]

but what stops the cpc in the installation carying the same current as in the phase neutral? ive just got myself confused???!

 

[Had8Lives]

As described by Des, the neutral conductor in PME is spiked (connected to the ground) at multiple points on it's route to consumers, therefore you cannot get a shock off it in theory as it is at the same potential as you stood on the ground.