Ok, my first question here. In my spare time, I run a small PA company. On Saturday, I had a concert at a sports center where I´d never been before. Power for the event came from a standard 5-pin, 16A outlet. After connecting to my distribution unit, I got the multimeter out and checked the voltages. I found:
Line -> Neutral = 230v (on all 3 phases).
Neutral -> Earth = 0v;
Line -> Earth = 0v.
The last reading obviously threw me. Over the years, I´ve seen all sorts of 'floating' earth to phase voltages, but never 0v.
So I checked the voltage at the outlet on the wall in case my cable or distro was the problem, but found the same thing. I then checked with the guy in charge of the place, but he wasn´t much help. There was no other outlet in the hall, nor would he let me into their mains 'cubby hole' - at least not without their electrician present, etc, etc. All he said was that they have regular events there and have never had any problem with the power.
So I set up, made sure that the mics, etc. were safe and did the gig.
So my question is simply, what circumstances would produce a 0v Line to Earth reading?