The snubber circuit is there to protect the triac. When the triac is turned on, it is almost a short and AC voltage and current travels through it to the output. When the triac is not turned on, AC voltage will still pass through the snubber, as AC will pass through a capacitor, but the impedance through the snubber circuit is so high that usually only 5 mA maximum can flow. (This is generally referred to as leakage current.) Read the specifications for the field device to make sure it cannot be turned on by this leakage current.