When something stops working, such as outlets or lights; when the
lights are flickering. Sometimes you get small shocks from the
plumbing. These are things that require troubleshooting.
This
means simply finding and repairing the problem. Since there is no way
to know the amount of time or materials this will take, it can't be
set-up as a bid.
Unfortunately, it's also the time when people can get taken for the most money; that's because it's hard to understand if someone is really fixing the problem or just spending your money!
As they have more experiance, Electricians can get an idea of how
a structure is wired and where the problem may be.
Troubleshooting
is not an exact science! Look carefully and find an Electrician with
the experiance to get this right.