I'm considering on creepage distances on my PCB. I have read UL840,there are two significant tables. 6.1 "Minimum acceptable creepage distances" and 6.2 "Minimum acceptable creepage distances on printed wiring boards". I have read post: Trace width and clearance calculations. I noticed that Dave Tweed recommends to use 6.2 table. But in table 6.1 there is a sentence: "Creepage distances for equipment subject to long-term stress". I'm considering what does it mean, and when i should use values from table 6.1?
Electronic – Creepage distance get from UL840 note
creepage
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The biggest clue that the part is OK is the UL Recognized component mark (the backwards-looking "RU" symbol with C and US) on the part.
You will have to make sure that your PCB traces keep the necessary creepages and clearances, but the part itself (and the pinouts) are perfectly acceptable per UL and therefore not a cause for concern.
The pinout logic is most likely a function of the physical construction of the part given the form factor, or it could be to make it pin-compatible with some other vendor.
Here is a diagram that should help: -
Picture taken from this document.
Please also note that creepage distances might have to be bigger dependent on your pollution category and your material group. See this document for further info.
There is also this calculator - I have tried it and for 250V AC, the protection distances seem to be right i.e. basic creepage is 2.5mm with 2.5mm for supplementary making a 5mm total for reinforced. Ditto the clearance figures - they add up to 4.0mm for reinforced: -
Best Answer
The difference between 6.1 and 6.2 is based on the continuous voltage differential between the traces.
For example: If you expect a continuous 1000V between two traces, it should be spaced according to 6.1.
If you only need to be able to withstand a 1000V surge infrequently and/or for brief periods of time, then the spacing can be according to 6.2.