Hello:
Years ago when I was required to start designing electronic controls to meet the EN60335 requirements I was under the impression that I needed to have 4000V isolation and at least 8mm creepage AND clearance between any high voltage to low voltage.
When I say high voltage I am refering to120 or 208/230/240VAC line voltage. When I say low voltage I mean any circuitry connected to secondary side of the power supply transformer where an end user will come in contact, like a user interface, say push buttons or temperature sensors.
More recently a few people have told me that this spacing and dielectric strength really depends on the contamination level of the circuit board. If it is in a clean environment, you really don't need the 8mm clearance. Is there truth to this?
Thank you, Andy