On Friday, December 5, 2014 11:38:14 AM UTC-5, wrote:


My first concern would be whether there was enough room in that box on
the inside for another cable.
If it is the last one on a run, it is probably OK. If there is a cable
in and a cable out, the box is full.


In that case he might be able to locate the outside outlet so that
he could disconnect one of the cables that goes to the existing inside
box, run it to the outside, then run from the outside box back to the inside
box. That could work depending on how the cable runs, how long it is,
and the possible locations for the new outside box.