What is good practice device to protect line input? Could be to a transformer or diode/thyrister circuit. I'm using a fusable link on the pcb in and out, and a line rated X1Y1 cap across the ac input. http://www.digikey.com/product-detail/en/DE2F3KH103MA3B/490-4217-ND/1021453 It's in a noisy environment. Hand held drill. I'm thinking a mov might keep blowing fuse from the noise. Noise won't effect the rest of circuit. Maybe nothing is best? Also have a diode across diode/scr bridge. Corner to corner. Redundant?