Electrical distribution along lighting grid

At 240V, Ron, they don't need to land multiple phase lines to get the needed voltage.
Perhaps not for the voltage, but the phase rotation would still be useful, especially for three phase motors. Our tab motor is three phase, but we run it from a single phase with a three phase inverter. We can vary the line frequency to a certain extent, which of course affects the speed of the motor.

I was told their logic was to keep the three phases well separated in an attempt to prevent staff from receiving a 240 volt shock.
Indeed, the separation of the three phases used to be stipulated by the regulations ("code"), the idea being that it would be impossible for someone unskilled, even with very long arms, to be able to physically touch the line of any two phases. That requirement was removed some years ago, and now you'll find all three phases often brought out on the same patch panel side by side, but the use of RCDs has also greatly increased since those days. A phase to ground or phase to neutral shock would result in a 240V shock, even now. Phase to phase would result in a 415V shock, so I guess you could see why they didn't want any old Tom, Dick or Harry poking around different phase connectors, but skilled staff shouldn't have been a problem, even then, since we used three phase devices back in the 90's.
 
I was told their logic was to keep the three phases well separated in an attempt to prevent staff from receiving a 240 volt shock.
Good plan until productions arrive requiring all three phases at the same device(s) and / or are counting on common neutrals for their 3 phase distribution.
London was 1996 and the second time our shop built, supplied, and installed all of "Tommy".
In 1995 we did exactly the same for a German producer in Offenbach / Frankfurt am Main, Germany where the Germans had no trouble feeding our 3 phase / 5 wire 125 Amp Cee-forms.
Toodleoo!
Ron Hebbard
Any new theatre, conference centre, or music venue being built in the UK today would probably have a number of company switches in the wings or back stage with multiple 3ph. outlets of various sizes. So you wouldn't have the same problem today.
 

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