The first photo below is me standing next to the coil, I'm 5,10 so it gives some idea of the size of the complete unit. All the arc photos were taken at different power levels up to and including 20kva. The coil stands within a steel clad building where I work. The roof truss is 4 metres directly above the top of the coil. Some of the power arcs went across the truss, a distance in excess of 4 metres. There were 8 people present at this session. The toroid used is 40 inches in its major diameter, 12 inches deep.