The KiCAD calculator can calculate these things for you when you know the sizes. The metal tracks are obviously uncoated external layer tracks. Attached are some examples.
By the way, for anything connected to 230 V AC mains, you need at least 3 mm of spacing for equipment with safety earth and 6 mm between conductor and anything you can touch without safety earth. That's because there can be nasty voltage peaks on the mains when a large load is switched off or lightning hits a high-voltage line.
The first one is a DIP board, also.
In a seaside environment, electricity can short 1000 v per inch. I'd say 32 v max between adjacent pads, maybe .032" apart? 1/32"?
The reason 1n4007, rated 1000 v piv, is such a laugh. Too short for that.