I have a programmable switch that requires a neutral line to work. The
switch boxes in this old house do not have a neutral line. I was told
this by an electrician.

However, my son has a newer house, which may have a neutral line. I have
an old Wiggy voltage tester. How can I test for a neutral line? How can
I tell the identify the line, the load, and the neutral (if there is
one)? I believe the ground will always be a bare wire, right?

Thanks