Turning off a branch circuit breaker at an electrical panel is not the same as unplugging the equipment from the wall outlet. Distance...
Take a Square D QO single pole 20 amp breaker. In the open position the two contacts are about 3/4" apart. A several 1000 Volt lightning transient will easily jump that divide...
@jea48 , would a several 1000 Volt lightning transient be like a direct hit?