I once ran 3 20 amp circuits thru what was left of a burned out home as
a temporary service. The existing wiring was toast, and had been done
by a idiot Like finding 2 lengths of romex in a wall, tied together
in a knot, with no box or support. It was a wonder the bad wiring hadnt
caused the fire. cat knocked over lamp.

Had a failling out with our houseguests, they were here 7 months and
got too comfy, they had no insurance for replacement living.

anyhow I heard later their electrician remarked whoever did the
temporary did a good job

I suggest the original poster run a proper line if he figures this may
be needed again in the future