Moshe, In general:
APPROVED "X" capacitors are required before the bridge. APPROVED "Y" capacitors are required throught the primary circuitry. Varistors are allowed from line to line, but cannot be used by themselves from line to ground. If used from line to ground, they can be placed in series with a spark gap meeting the creepage and clearance requirements internally and externally. If used from line to line they shall be placed after the fuse. Hope this helps. Regards, Edward Eszlari TUV Rheinland
