Hello
The problem is that there is capacitive coupling (badly called induction) of the live cable with the return of the reflectors, the coupling is greater the closer the live one is to the return, the longer the distance they go together, and the further the distance is. live ground wire (not forgetting that you have a round wire and no grounding wire).
The solution in putting in the reflectors that make problem a capacitor between the terminals of this one, that capacitor you get it in the houses of electricity like "inhibitor of flash".

And of course, as Ricardo (greetings) says, connecting a grounding cable to the reflector is really important to avoid possible inconveniences.