EN60335-1 safty standard question

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
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Hi Andy
In 60335-1 the clearance varies with voltage and creepage varies with voltage, material group and Pollution degree. If you intend to design a product to the requirements of a standard, you must have a copy of the latest version of the standard available, otherwise you will definitely get it wrong. I work for TUV Rheinland in the UK and most of the products that fail on test, fail because the designer did not read the latest version of the standard before he finalise the design.
If the product you are designing is for sale internationally, you need at have a copy of IEC 60335-1, plus a copy of the applicable part 2 standard and a copy of the IEC CB Bulletin that covers the countries that the product is to be sold into, to have any chance of design a product that is fully compliant.
BillB
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Yes I do have a copy of this standard that we purchased a few years back. There is a table in there that lists different creepages and clearances for different situations, but I have never been quite sure which row in the table would apply to the "high to low" situation I refer to in my original post. I do know from past experience that if I stay with at least 8mm I will not have an issue with this spacing when the board goes out for agency approval, but I am never quite sure if I can get by with less spacing.
Thanks, Andy
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Rubber Gloves!!

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