Creepage Distances

[David]

Hi all,

I have a quick query regarding creepage distances and how they are defined. Standards such as EN60950 specify the creepage and clearance distances for, amongst other things, "current carrying parts of different polarity". Now, obviously the Live and Neutral lines in a circuit will be constantly alternating polarity. Does this therefore mean that the same creepage distance is required between say the neutral and some other circuitry and the live line and other circuitry? Also is "working voltage" defined as the potential difference between two conductors?

[Kremmen]

IEC 60950 talks about curent carrying parts and conductors in many places, but the creepage distances are mostly laid out on Annexes F and G. The distances apply only to circuits with the defined overvoltage classes in table G.1. The required clearances are listed in table G.2. Earlier in the text you will find tables 2L and 2N based on the working voltage of the particiular circuit. For the definition of working voltage see 2.10.2.