Paul,
Thanks for you reply,
I was figuring:
A couple of years ago I had to install an underground feeder to a shed/workshop in January, and it was one of those rare English days when the temperature remained down at almost freezing point until well into the morning.
That January is the middle of the UK winter, it's the middle of our Summer.
But on the subject of cable types and regarding that link, concentric cable, is what we call Neutral-Screened, you can only use the outer screening as an Earthing(or if you are really slack in your quote, a Neutral)Conductor.
But, Paul, trying to bend any large diameter cable in cold conditions, has a risk all of its own, I posted a topic a while ago about installing a 300mm2 Al cable, and believe you me, the cable did not like being bent at all, this cable had XLPE insulation on it(as all cables of this size do), It wasn't the Al conductors in the cable that didn't like being bent,it was the outer and the core insulation that was moaningabout being bent, we've had XLPE cables split on us in really cold temperatures.
XLPE is nothing but a s**t-bag, to try and run in cold areas.
Regarding our LV cables, we have used the sheathed Earth conductor since the early 70's, I hope that our Australian folk can back me up on this!.
This method(to a certain extent) cuts down on Earth-Leakage currents, through the length of the cable.
Paul, over here in NZ, We are required to run an Earth continuity conductor to all points on a circuit, regardless of wether they are required or not, makes sense though, in the example that you gave, I have lost count of the times that I have sworn and cursed the Electrician that fitted the Double insulated light fitting and chopped off the Earth wire.
(Again I would ask for the input of the AUS sparkies to let us know how it is over there).