Operation of Fluke VoltAlert depends on the user's proximity to the sensor's barrel

Here I demonstrate how the operation of a capacitive voltage sensor depends on the user's proximity to the barrel of the sensor.

[@Joso997]

Hi. We have developed a similar detector but are having a problem, it fails to detect when it is raining, the antenna is fixed on the insulated 230VAC wire.
It works fine when it is not raining. Do you have any idea what property could be changing when it is raining? Also the stronger the rain, the stronger the effect.