As far as my experience is concerned there is no definete timeline or warranty for Residential Wiring cause after we Intalled such electrical wiring we make sure we perform detailed Electrical Tets and Standard procedures,the rest comes from Good Maintenance of the owner provided that they are well informed when troubles occur.
ABCD, checking your work after installation is standard procedure, but as we all know any man-made item is bound to fail with time, what I get from your post is this, a light fixture you installed 20 years back is still under your warranty, I would think not.