So I set out to replace two bathroom fixtures, something simple right. Not. Pulled the first old fixture over vanity, no box just a romex tail. Removed ceiling fixture, a feed and 2 wire switch loop. Strange, a two gang box with two single pole switches. So I used my 4 " holesaw to cut a box in. I find a open carlon round box with four 12/2s in it. A nasty diy set up. As soon as I finished dissecting old carlon box, I traced feed to an old bar box with an octopus of wires. Well 2 1/2 hours of rewiring the fixture box, outlet in bedroom, and installing a box in the attic and clamp on the water pipe I was able to install two new fixtures.