I am designing a 3-phase voltage detector based on optocouplers as shown below:
For this I need to follow DIN 60664-1 and my biggest problem is to understand how to apply those rules for creepage and clearance. Namely, I figured out that with polution degree 2 I need to stick to the following measures: 3 mm minimal clearance and 4 mm minimal creepage. Fine, but how is that achieved in practice? From the circuit that I have shown, how do I determine the creepage and distance between L1_1 and L2_1, or between L1_2 and L2_2? Does that mean that for every point in the circuit I must calculate the voltage and then determine the creepage and clearance in the standard?
Take a look at the resistor connected to L1 and L1_1. It is 0805 size, but should leg L1_1 also have clearance and creepage of 3 mm and 4 mm with respect to the L1?
At which point may I bring lines closer to each other - legs of the capacitors connected with the optocoupler - there can never be a breakdown between them because the diode keeps that voltage low.