I had a "mystery" wire running through a wall I needed to remove for my
kitchen remodel. I say mystery since I could not figure out why it
went from the attic to basement and what it was controlling. Rather
than spend a ton of time tracing it, I just killed the main breaker and
put two junction boxes in - one in the attic, one in the basement (both
accessable) - and moved it to pass through the wall that was not
getting torn out. It got me thinking - is there a code requirement on
how many pieces of romex can be fastened with one strain relief? I
used standard 4X4 metal boxes with the round strain reliefs in a side
knockout (not the ones with the built in dual clamps on the bottom of
the box). For the attic run I used two strain reliefs with the wire
entering and exiting on opposite sides - the same way it was running.
In the basement I fed them both through one knockout because I only had
one left. It's standard 14-2 romex.