The current through a capacitor is I = ωC, where ω is in radians per second (ie, 2𝜋 60 Hz). I think 220 kV is the RMS voltage, so you get RMS current from the

The current through a capacitor is I = ωC, where ω is in radians per second (ie, 2𝜋 60 Hz). I think 220 kV is the RMS voltage, so you get RMS current from the formula above. Peak voltage would be √2 * 220 kV. Indeed, both the capacitor and the arc are in series, so actual current and power is somewhat less. As the arc grows longer, there should be an optimum length where you get 1/√2 of the maximum power.