Apparent voltage on plastic service head

Have you tried putting your other hand on [*] the service head, by the neutral, to simulate the final stages where instead of pointing the stick at the surface/insulator, you reach around (~0.23) so the knuckles of the holding hand are that much nearer the neutral greatly increasing the capacitive coupling of your body to the 'earthed/neutral' and cross bonded metalwork?

[*] perhaps with a piece of cling film or thin poly bag for extra safety, in case that case is actually partially conductive ;-)

Aside: for an electronics folks (frequencies >75Hz ;-) this stray capacitance is why the old fashioned idea of disconnection of an oscilloscope earth for those metal cased Tektronix 'scope didn't work - the case to ground capacitance was already sufficiently high that it still provide a ground loop return path at any reasonable HF frequency.

It's a fun calculation to consider [just] two 1cm^2 plates separated by a piece of sellotape, in picoFarads, then scale it to the human body, then scale it to impedance at operating frequency - it's how most noise get's into electronics, from the PSU switch and the metalwork! Try 230V through 1pf into a 10kohm sensor input impedance, on e of those high sensitivity ones..

Have you tried putting your other hand on [*] the service head, by the neutral, to simulate the final stages where instead of pointing the stick at the surface/insulator, you reach around (~0.23) so the knuckles of the holding hand are that much nearer the neutral greatly increasing the capacitive coupling of your body to the 'earthed/neutral' and cross bonded metalwork?

[*] perhaps with a piece of cling film or thin poly bag for extra safety, in case that case is actually partially conductive ;-)

Aside: for an electronics folks (frequencies >75Hz ;-) this stray capacitance is why the old fashioned idea of disconnection of an oscilloscope earth for those metal cased Tektronix 'scope didn't work - the case to ground capacitance was already sufficiently high that it still provide a ground loop return path at any reasonable HF frequency.

It's a fun calculation to consider [just] two 1cm^2 plates separated by a piece of sellotape, in picoFarads, then scale it to the human body, then scale it to impedance at operating frequency - it's how most noise get's into electronics, from the PSU switch and the metalwork! Try 230V through 1pf into a 10kohm sensor input impedance, on e of those high sensitivity ones..