I am trying to figure out how this handheld unit works for detecting
power. I don't have a manual.
I am disconnecting and removing electric baseboard heaters. I just want
to figure out which fuse controls this power circuit. Even with all the
breakers thrown my handheld AC Sensor gizmo seems to beep furiously as
if there were power. I know there is not because when I turn the heater
switches ON they do not heat up.

Can anyone tell me how to use this thing to determine if the power
lines are live? (working intuitively - admitedly not a good idea with
electricity - I hold the side button down and pass the unit over the
leads. But it still beeps.)