Piotr:you say: “there are no reason to have both its sizes to belong to different net classes.” However, the tracks at the R803 terminals do not necessarily have to have the same characteristic: For example: on the left a high current and a high voltage, AND on the right an almost zero current and a very low voltage (in order to simply “read” , measure…) or here a tiny proportion of what happens on the left track.
So if the presence of R803 can solve this problem of different characteristics, with a huge track on the left and a very thin one on the right, there remains an essential placement/routing problem: R803 MUST "stay as close as possible to the input pin of the “AOP” in order not to end up with a noisy AOP and the risk of unwanted oscillations, especially in a context where high voltage and/or current values are present…Only possibility: The track connecting the net class “dangerous” at R803 left side must be “very fine” and convey the voltage “nicely” to the place where the measuring AOP is installed.
Naïb : I obviously have these 2 net classes…As for the example of a CMS 1206 suitable for 400V, firstly “this is not the subject here”, and secondly, go and defend your opinion to very large manufacturers of HT resistors, I doubt that they will listen to you then .
Kicad have a calculator if you do not believe me.
ALSO just because a part might be able to survive a voltage, doesn’t mean a CCA will … how you do your PCB is not the responsibility of OE’s but yours. Also you mentioned your working voltage is 600Vdc so why are you considering a 1206 which “works” at 400Vdc, this makes no sense and is dangerous.
In fact if you only use IEC-60664-1 then 400V requires 1mm (assuming a PERFECTLY clean board…) and thus 400Vdc and a 1206 is subjectively compatible. BUT a 400V part, with 1.7mm pads used to standoff 600Vdc is not…
I have freely given my advice that using a single 1206 to support 600Vdc (uncoated, no board pollution) is not advised. Do with this advice as you will
Since this thread begin it is very hard to me to understand what you want to say (because you insert some sentences that are not directly related to the subject - something about Einstein for example).
Now it looks to me that it is also for you hard to understand what I am trying to say.
I said:
Now I see I wrote ‘sizes’ instead of ‘sides’ by mistake. But I believe it was clear that I am speaking about both N1 sides.
How do you understand if I’m talking about two sides of R803?