By default, I was the electrician. Even our own amplifiers had different plugs on them, and no-one thought of standardising or using a distribution board. The usual procedure therefore was to take the plugs off all the power leads, twist the lives (red) and the neutrals (black) together with a separate length of cable, bare the wires at the other end of the cable, and poke them into whatever socket was available using matchsticks to keep them there. The junction point, where all the wires came together, was put under a carpet or mat for insulation…
Amazingly we never had a fire, and although I did receive a number of shocks myself, we never managed to kill anyone.
But guitar amplifiers could be dangerous; even later on, earthing was frequently not present, and it was not unusual for a microphone or the guitar pickups to float up to mains voltage. All was well provided nothing that was earthed was touched, but I saw a bass-guitarist from another band once get a shock from a microphone, sufficiently violent that he broke his guitar strap and the guitar crashed to the floor. He was unhurt but very shaken.
There were lighter moments though. In the early days we played at a dancehall in a hotel, long since demolished, on the seafront at Dovercourt in Essex. They had their own PA system with expensive moving-coil microphones, and some engineering genius had fitted the microphone leads with small, three-pin round plugs, identical to mains plugs, for plugging into the PA amplifier system. Amazingly, the hall had the same mains sockets for power. One of us, who shall remain nameless, decided to help me set things up. He saw the microphone plug, plugged it into the mains socket and switched the latter on. I was standing near the microphone. There was no sound, but an exquisite, tiny, ring-shaped puff of smoke exited from the microphone as its fine moving coil, having been connected across the national grid, was reduced to its constituent atoms.
Quietly, without alerting the hall manager, I unplugged the microphone and moved it to the side of the stage; we had to make do with just one microphone that night.