Measuring peak high voltage, whether DC, AC, or impulse, often involves Sphere Gaps – a standard method. 

These gaps are set up in two configurations: Horizontal and Vertical. The Horizontal setup is preferable for lower voltage ranges. In both configurations, one sphere remains static while the other is adjustable. In Vertical setups, the lower sphere is grounded, whereas in Horizontal setups, both spheres are typically connected to the voltage source or one may be grounded. 

Series resistances are used between the source and the spheres to control breakdown currents and dampen undesired oscillations.