Maximum hole or slot size (electrical safety)

[Jester]

Assume you have a power supply with hazardous voltage (240Vac) inside a non-metallic enclosure that requires some cooling, hence some slots in the enclosure to aid with cooling. I recall the slots must be smaller than some dimension (tested with UL test finger). The closest hazardous component (a fuse) is spaced 250 mils behind the slot.

Does anyone know what the maximum opening size can be that will prevent the finger from accessing the fuse?

 

[FvM]

The smallest test pin is 4 mm diameter / 100 mm length according to IEC 1010.

 

[Jester]

FvM,

Thanks, you always seem to have the answer.