As a hobby project I'm building a power line monitor to detect when a load is switched on and turns on some additional loads. I have
120 V 220 V running through my board and was curious what the standard board spacing is for high voltages.
I'm sure there's some specs by UL or other agencies for this, but I'm cheap.
Correction, the voltage I'm working with is 220 V, powers a cabinet saw. In any case, is there a general formula, possibly even for higher voltages (e.g. flyback for fluorescent lights)