I was doing a job in a large cathedral in Southern England where a VIP was to make a public broadcast.
I walked in, all the lights, sound recording kit etc: ceased to function.
I went out to one of our vehicles..everything came back on again.
I returned to the cathedral, blackout and silence and ..chaos.. ensued.
Blokes I was working with collapsed in hysterics and when questioned by a cathedral Deacon told him of my beliefs. He asked me to leave the building and all the lights and sound gear came on, much to the relief of the BBC TV techies.
True story, a sheer fluke and probably a dodgy main connection somewhere, but I've been Wicca ever since..