So the general sportsmobile electrical lay out is two 30-amp circuits, one for the passenger side, and one for the driver side. The driver side also covers the front overhead area. The water pump, ceiling lights and some individual equipment have dedicated fuses for them off of it. Refrigerators, Heaters and radio circuits generally are fused at fuse box. The fans generally don't so the fuse protection would go back to the 30-amp circuit fusebox.
If the cutting the wire caused a spark, I suspect it is still energized. Also I would expect that you would have reported other devices not working. These power wires generally run behind the side wall to roof rail trim. Sportsmobile generally uses the crappy piggy back taps off of those wires. It would also be possible they transitioned off of the 12 volt socket you said was close,
If you do not track it back to the source, I would split the zip wire, and tape off the individual sides, or preferred use glue lined heat shrink to terminate.
This of course is their general wiring practice, no guarantees yours is wired this way, or hasn't been changed by the previous owner.