Hi,
if you want polarity free isolated switching without a relay try a MOSFET based Solid State Relay (SSR).
Omron make the G5VM series, NAIS the AQY210 and AQY221 and IR the PVA2352 and PVG612
They are basically opto coupled MOSFETs. There are normally two FET's in series so the body diodes don't conduct on AC. The input is just an LED so there are no noise or common mode problems with long wires. You just need a series current limiting resistor on the pic output like any other LED.

Robert G8RPI.