Properly connected, the probe is rated to 15 kV Overvoltage Category I. The use of the probe is restricted to low energy applications, which are energy limited circuits like electrostatic air cleaners. Do not use this probe to measure high voltages on power distribution systems. The probe is a precision 1000 : 1 voltage divider formed by two matched resistors. The unusually high input impedance offered by these resistors minimizes circuit loading and thereby optimizes measurement accuracy. WRead