"You may also want to consider starting with a wall mount unit that goes directly to +12V DC ... you are doing your small part to keep mother earth green and nice."

...And to keep yourself safe!!

This approach removes the need to mess about with anything at 220VAC - or even to have it anywhere inside your unit!

If you are designing a product for sale, this can be a major consideration on the Legal/Regulatory front! (especially as the question seems to suggest that you are not too familiar with power supply design?)