[Joseph]

What I do is:

1) Trip breaker at panel.
2) Return to all outlets and test with multimeter to ensure no power.
3) Physically remove all outlets from boxes.
4) Ensure wires are sticking straight out away from anything combustible or anything that would result in a short (metal box, etc).
5) Reset breaker at panel.
6) Using a multimeter, probe each set of wires until you have power, that one is first in the chain and is where you place the GFCI outlet.
7) Trip breaker at panel.
8) Return to live wires as found in step 6 and test with multimeter to ensure no power.
9) At location found in step 6, install GFCI outlet.
10) Replace all other outlets.
11) Reset breaker at panel.
12) Reset, Test and Reset the GFCI outlet (they usually come tripped for safety reasons) .
13) Test for power at each outlet.

Done!


Keep in mind that you can wire a GFCI outlet incorrectly.
There are two sets of lugs (Screws). One is marked "LINE" and the other is marked "LOAD."
"LINE" is connected to the incoming power (the two we found in step 6).
"LOAD" is where you connect the set that continues the circuit from there.

Also note that the lugs are color coded as are the wires. The lugs are brass and silver.
The "Hot (Black)" wire should be connected to the "Brass" lug and the "Neutral (White)” wire should be connected to the "Silver" lug.



Good Luck!



Joseph