To have a neon lamp properly switched on, two specific appliances are required. These are the starter and the reactor:
The starter acts as a timer switch, consists of two electrodes contained in a glass ampule containing inert gases.
The ampoule is in turn contained in a metal tube. At start-up, the starter switches on current for 1-2 seconds then opens the circuit.
This timing is necessary to cause incandescent discharge filaments to glow in the gas contained in the lamp.
The reactor instead it regulates the current intensity of the lamp, allows it to be switched on and then enables the power supply.