I am a retired Electrical Engineer, while I have never seen ball lightning, I have seen and created the equivalent while testing high current DC Motors. The Interrupter ( like a circuit breaker) for DC current has arch chutes that help extinguish the current when they open for protection. I have created arc balls bigger that a beach ball that travels as much a 50 feet. The sound that accompanies these balls is like a cannon going off. This is quite a sight and very nerve racking when you know the consequence of the interrupter not working.