I read a discussion about upgrading two prong receps to three prongs. I opted for the GFCI at the first outlet in the series and regular three prongs down stream.

In one of the circuits, the last recepticle in the series was connected through a switch. So there were 2 two-wire feeds into the box. There was the hot wire and its nuetral, then the other wire had its neutral hooked up. However the black wire was not stripped. It simply had a twist cap on it.

I assumed that this was a load wire that dead ended. I hooked the one black to the hot terminal, and the two white wires to the nuetral terminals. The GFCI reset perfectly. However, when I plug anything into the last recepticle and turn the switch on, it trips the GFCI. What have I done wrong and how do I fix it.

Joe

 

Sounds like the switch controls something else and that it crosses circuits. (i.e. that it mixes a hot and a neutral from two different circuits.)

Figure out the wiring first, correct the wiring and then use your GFCI.

 

Racraft could well be correct and figuring out the wiring is certainly step one but this may have been meant to be a switch loop switching all or half the receptacle. If it is a switch loop then the white wire coming from the switch would not be connected to the neutral side of the receptacle. Check the switch box to see if this is a switch loop or if another power source is present in the switch box. If this is a switch loop then your wiring is incorrect and your Gfci is detecting a current change on the white wire when you toggle the switch. While your at it check to see if the tab between the brass screws of the receptacle has been removed. Post back with what you find ...RL

 

Sorry, but this fits no known legitimate wiring pattern. Something is out of the ordinary here, and it's impossible to draw any conclusions with some testing. There is a strong chance that somebody has been working on this circuit who didn't know what he was doing.

 

John you are correct.

Two more pieces to the puzzle. There is a ceiling light. And there is a security system in the house.
We have figured out that the true beginning of the circuit starts in the ceiling light. From there it is a mess. There are black wires that turn into white ones, white wires that have no end visible, and stray 117 voltage on both black and white with the entire circuit opened at the CB outside. Our guess is it is a combo of poor 1950's wiring plus some lazy security system instalation.

Thank for the help. If you want anything more in-depth, let me know.

Joe

 

One more thing.

The owner and I have reconsiderd the options presented in the much earlier post. Downstream GFCI is out and pulling new wire throughout the house is the new choice.

Joe

 

Well I screwed up should have read the post more carefully read it as one power source and a cable from the switch coming into the receptacle box....RL