Ed_Gee wrote:
JUST BE SURE YOUR BREAKER IS OFF FIRST !
And after you THINK the proper breaker is off, test for voltage anyway. If you see one more wire than you think there should be, there might be TWO different circuits using the run.
Also try to make sure that you can tug enough slack in the existing wire to actually make the splice that you want to make.
If the existing wire is exactly behind where you want the new outlet, then you should be able to use the two sets of screws on the new outlet to effectively splice the wire back together and no wire nuts will be needed......except maybe for the ground.