detect AC voltage

Hi,

Ahem, don't mean to be a downer, but what kind of insane worst case scenario is this taken from?

It's from the german laws that where made to prevent severe accidents caused by electrical appliances.

Wikipedia says : Electrical injury - Wikipedia

It is sometimes suggested that human lethality is most common with alternating current at 100-250 volts, however death has occurred from supplies as low as 32 volts and supplies at over 250 volts frequently cause fatalities.

Worst case? Yes.

Don't miss the next question in our series :
Do I really have to wear a seatbelt when driving slowly?

Eberhard