D Yuniskis wrote:

Sylvia Else wrote:

Phil Allison wrote:

The MEN system:

In Australia, AC power delivery uses a system called " Multiple Earth
Neutral " - which requires that the neutral conductors in a
premises be connected to the plumbing system at the distribution
board (ie power box). It also requires that an earth stake be
installed for the same purpose, but some older premises may not have
this.


If as you say, neutral has to be tied to Earth at the premises, then I
can indeed see that the situation might not be so bad.


Grounding the mains to "plumbing" *was* common in the US many
years ago. Now, I believe, you *must* ground to a metal
rod driven into the earth (8 ft?). Note that if the water
meter was removed, your earth-through-plumbing would fail.

On the face of it, having significant current flowing from neutral to
Earth would have to indicate a fault. It would be nice for the
breakers to trip in such a situation, but I can't see that they will.


This is how GFCI breakers work -- they watch for current "leaking"
off to ground someplace other than in the "return" conductor.

Please don't go there, there are many experts that really don't know
how a GFCI is suppose to work.

They thieve on the idea that most units now sold have the arc
detection in them and no longer label arc (AGFCI) detection as part of
the unit,which does not require a ground path, along with it having the
original ground fault system which does require grd path to fault.

Those that have installed these units in outlets that have no ground
in them, there by, allowing the unaware person to become the ground for
it. They think it's ok because just sliding the plug in/out, which
causes those nice little arc's to form, from the appliance load, will
trip it.

And it's obvious, if you don't have a working ground from the
receptacle to the appliance, the GFCI isn't going to work very well when
the appliance starts generating small little intermitting shorts that
would normally trip the device if the ground on the appliance was
present to unbalance the common mode device in the GFCI, with out taking
out a human in the process.

Devices like lamp cords, that normally do not have a grd terminal, are
excepted because, the arc detection will actually trip, some times. They
have to be rather large ones before they work, and other times, things
like high powered radio's going by, will false trip them.. That's what
you get for trying to accommodate those that don't want to do it
correctly. This problem is also prevalent in AF-breakers and code allows
variance to accommodate for life saving equipment and the like.

I just love it when the building inspectors use their U-ground testers
on GFCI's that have no working ground at the receptacle to find it not
tripping when they hit that GF test. It brings a smile to my face..

Have a good day..