Hi,

As steve mentioned that glitches do get reduced at the secondary side. With simple filtering it should not be much of a problem. If using on an external interrupts a choice of rising/falling edge can be made. Dips or Spikes, can't avoid both. Why not test it out Michael ? After your DC rectifier (Bridge/CT) put an additional diode to the filter cap. Take your signal before the diode and feed it with a 10-20K to the PIC. Posssibily its a schmitt trigger input so don't worry about shaping the signal.