please see this circuit. http://www.emanator.demon.co.uk/bigclive/ozone.htm
in the first part of the description about making an ioniser /ozoniser,just above the pic of close-up view showing the emitter and tube, and also the neon output level indicator.
you can read like this.The connections between the sections of voltage multiplier are just thin hookup wire, since the potential between stages is relatively low at a few hundred volts. The output goes via the usual safety resistor/s and also passes through a neon and capacitor based current flow indicator as used on the ioniser page. The final output is on three needles pointing at three short tubes made from brass eyelets soldered to self adhesive copper tape. The tubes are all conected to mains neutral via a few safety resistors. suppose i use a two pin plug and i accidently changed from live and neutral,it will be really hazardous.any methods to prevent it?