I have a circuit in my house that provides power to 5 receptacles in my living room. The receptacles are all wired in series...that is, when I look at the wiring under my house, I can see where the power comes out of the breaker box to the first receptacle, and then from the first to the second, and second to third, etc etc. on to the last.

A few years ago, I needed to add an additional receptacle outside, so I added a GFCI receptacle to that circuit by cutting the line between the second and third inside receptacles. On occasion, the outdoor GFCI receptacle would trip (usually during times of heavy rain...which I attributed to some water getting into the GFCI outlet box) and naturally all of the "downstream" receptacles would then go out as well (i.e. #'s 3, 4 and 5). After a few hours of drying time, I could just go outside and reset the GFCI and all would be well.

A couple weeks ago, the GFCI tripped and I have not been able to get it to reset even though it has had plenty of time to dry. Not having the time to look into it right away, I just went under the house and took it out of the circuit so I could restore power to all of the downstream indoor receptacles that had lost power.

Yesterday afternoon I finally had enough time to try and tackle the problem. Thinking maybe the GFCI receptacle had just gone bad, I replaced it with a brand new one; then went under the house and wired it back into the circuit as before. When I turned the breaker back on, the new GFCI outlet tripped...so the problem was not the receptacle itself. I then undid the wiring from the load terminals of the GFCI outlet and threw the breaker back on...I had power to the GFCI without it tripping...so I thought maybe the wiring from the load terminals to the downstream receptacles had a fault in it somewhere. I then completely replaced both the line and load wiring to and from the GFCI just to be sure. Turned breaker on and GFCI tripped again. I then swapped the line and load wires to/from the GFCI under the house just to make sure I had not mixed them up; turned breaker on and had power to GFCI but not the downstream receptacles. Frustrated, I then took the GFCI out of the circuit by re-wiring indoor receptacle 2 to 3 as they had originally been wired.

There is a fault somewhere in the circuit that is causing the GFCI to trip...am I correct to assume it is either in the wiring or a receptacle that is downstream of the GFCI...or would it be in the up-stream wiring/receptacles? Seems like if it was upstream then the GFCI would trip regardless if it was the #3 outlet in a series of 6 or the last outlet in a series of 3, so that's why I'm thinking the problem is downstream of the GFCI. What is the best way to find out where the fault is? I suppose I could remove each receptacle and somehow check them and then go on to check the wiring between receptacles if they check out OK? Thanks,

Tony