- One is the tiny existing can harmed vulnerable devices that do not have ESD protection, even although this can be solved with proper style. Yet another dilemma is, if lots of unearthed appliances using Y capacitors are attached together, the leakage currents will add up and certainly will subsequently exceed the secure grades. br br The supplies a reduced impedance return path for currents generated from the switching voltages amongst the primary and secondary windings of the transformer. Without this minimal impedance path, the currents will probably come back by other avenues - typically via stray capacitances from secondary into Live or ground or Neutral - often bypassing the input filter and generating considerably increased quantities of ran EMI."y capacitor" s suppress electrical noise and provide safety against electrical shocks and fires.