wrote:


I then was able to track down the fault - one multi-way extension
cable attatched to the many, many pieces of equipment had Earth
and Neutral reversed, thus connecting all Earths and Neutrals
in the middle of the studio as well as back at the mains Intake.

Ripped the offending extension out, the buzzing ceased immediately,
and the BBC and Public Image Limited got their recording and the
Sound Company didn't lose the gig or it's reputation.



** I know of a similar example involving a 30kW, 3 phase lighting system for live entertainment here in Sydney. Was back when lighting consoles communicated
with triac dimmer racks via 0-10V analogue signals.

The system seemed to have a mind of its own, lights came up and varied about with all faders set to zero. Bringing one fader up affected many others.

After hours of fruitless searching, the culprit was identified as the AC plug on the lighting console itself which had neutral & earth reversed.

Seems a roadie had fitted a new plug after accidentally damaging the original and told nobody.


..... Phil