I've been roped into helping a choir with sound when they are doing big gigs, but as a sound guy I'm a rank amatuer. We had a gig on Sunday where we also used a lights guy for the first time. We were both setting up and everything seemed to be going fine, the fun started when we turned the lights and PA on together. No power!! Lights by themselves were ok, sound by itself was ok.
In true "suck it and see" style we had blown two circuit breakers on a locked distribution board before we realised what the problem was. We were sharing a 15A power board, he was using two LEDs (which I understand don't draw too much power) and we run a 400W PA for the choir and a couple of 15W "practice" amps for the band which have lived happily together for a number of gigs including a practice session in the same venue.
The emergency electrician, after resetting, suggested that lights use a left of house circuit and I stuck to right of house, and we got through in the end. The lights guy said something about not running lights and sound on the same circuit but looking around on the web I can't see anything that says "don't do it". For future reference, can anyone shed any light on what might have been causing the problem?