Acid-based flux such as Tix or Nokorode should never be used for electrical work. The 18 gage red wire was dipped in Tix flux and left to corrode for 6 months. The black "control" wire remained shiny.
The MSDS for Tix and Nokorode list Zinc Chloride, a fairly strong acid, as the active ingredient. Use rosin or "no clean" flux, both weak acids, for electrical work!