Protecting the "earth" cable.

I'd like some opinions about the following scenario from other electrically qualified people. Please assume that the country may not be Australia but similar rules do apply (due to the lack of any other rules). Also, IEE rules do apply (which makes Australian rules generally valid in this case). Answers to this situation have already been given citing Australia Standards (AS NZS 3000:2007). The answer is not my answer.



QUESTION:
I’m having my electrical upgraded in my home in *******. The existing power that runs to the outlets goes through metal conduit within the walls. About 20%-30% of the outlets have grounds; the rest don’t. I am trying to minimize the amount of wires or conduit running over the surface of the interior or exterior walls.

I was wondering if it’s possible to use the conduit as a ground connection. If in all the outlets with ground I had a clamped connection from the green ground to the conduit and do the same with the non-grounded outlets would this work? I’d of course want to test each outlet to ensure that the conduit was in fact continuous but is this an acceptable way to get a ground to an outlet without running a new ground wire to it?
If I want to cut some channels in the exterior wall for the wire should that be in conduit within the wall? I was thinking of just a thin cut maybe 1-2 cm deep and just lay the wire in there to make it a little less unsightly.


ANSWER:
The ground is not a current carrying conductor (except when there's a fault), nobody will get a shock if they bang a nail through it so don't worry about protecting it in conduit. I reckon the option of a narrow slot with the wire buried an inch or so down would be a neat solution, you may be able to cut the slot with a tungsten-carbide tipped blade in a regular circular saw (don't use a solid carbide blade, they tend to shatter with nasty consequences).

It's worth considering just which outlets actually NEED grounding. It would be a waste of effort to ground any outlet which only ever gets two pin double-insulated appliances plugged in, grounding these will not make anything any safer (obviously leave two pin sockets installed here).

Looking around my place I see that, apart from my AV and computer equipment, 99% of ground-needing appliances are in the kitchen.


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