On Thu, 28 Aug 2003, Wouter van Ooijen wrote:

> >   Now the question: if the undergounded pipes have a smallest
> > resistance
> > than the proffesional house ground (which is perfect possible
> > because of the
> > different soil where these are undergrounded and the lenght of those
> > circuits, much longer in pipes situation) the pipes corrosion
> > will be huge
>
> Will it be? I guess you have AC mains, so there won't be much
> electrolysis.
>
  It's a very good question Wouter ! There are two reasons why it's
forbidden to use pipes for electrical ground:
1. gas pipes to avoid explosions
2. water pipes to avoid corosion, the electrolysis take place between two
electrodes, the earth is not a real electrode, it has a distributed
resistence, various oxids etc which attack the pipe surface which is wet
even in AC mode.


All underground metallic pipes must be isolated (not electricaly, it's
impossible) from the earth in polietilene foam. However there are plenty
places where the isolation is broken. Fortunately, now there are only
polietilene pipes even for 10 atmosferes.

Don't you answer me about my oscillator RC question with your 5V PIC
fadder conclusions ? :)

best, Vasile

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