Can't figure out the Issue

[FMC1959]

Let me first preface this by saying this house is very old, built in the year 1900. many of my neighbors homes were built in the 1890's, possibly earlier. A little rural village with 25-30 homes. I moved in, in 2020, a month before all the COVID lockdowns.

I have a light over our kitchen sink. Above it on the 2nd floor is the main bathroom. The toilet started having a leak at some point and water did trickle a couple of drops from the light and into the sink. A week or 2 later, the light stopped lighting.

I changed the toilet, and also changed the toilet flange and seal. That now looks to be working with no leaks anywhere.

The light has the light switch on the wall about 4 feet from the sink. It is a dual gang box with an outlet and the light switch. The light switch was fried. I also changed the outlet for a GFCI. Before installing the GFCI, I played with the wires a bit and saw that when I touched the light switch black wire to the one black line into the box, the light worked. Not knowing if there was still a short at the socket, I then proceeded to connect the GFCI line wires. Then connected the load wires going out of the box, not the light switch yet. I checked the outlet with a circuit tester and got the correct 2 green lights. When I connect the light switch wires to load, the black always tripped the GFCI.

I took the socket out from the ceiling. With the black, white and ground open/loose, the GFCI does not trip and the black wire shows power, using a no contact voltage detector. I added a new socket for testing and with the black & white connected, the GFCI does not trip. When I put a bulb in the socket, then it trips.

I didn't open the wall as it would also require removing a kitchen cabinet. But from the dual gang box, I can see the line wires coming in, then 2 loads going out; 1 for the switch and the other for something down the line, not sure what. The Romex 14/2 looks to go up the wall about 4 feet, then runs about 4-5 feet to the light above the sink. All looks pretty simple.

Taking the GFCO out, I could connect it with an ordinary outlet, but worry whatever is tripping the GFCI could fry the Romex wire in the wall, or the new socket, or new switch, or...something?

Anyone have any ideas what I am doing wrong, or how I should proceed?

 

[LXCam]

Pull the light socket and disconnect the white wire. Check for continuity between the neutral connection and the ground (mounting bracket, etc). If it’s bonded or shorted (continuity) that’s why. The current going out on the hot lead must be the same as the return current on the neutral (well within a couple hundred miliamps). With it bonded the return current is split (in theory)

Rereading, how do you have the ground connected to the fixture? Also you’ll need a cheap multimeter for testing continuity.

 

[sparky 1971]

You might not be doing anything wrong, the fixture could be shot and leaking a little current to ground. Also, you don't have to GFCI protect the light, but since it is tripping it you might as well just buy a new light.

 

[mm08822]

Since it's 1900 vintage, I'm sure it saw knob & tube, first versions of romex, etc. Possibly, someone connected a nuetral or ground wire to a pipe (SWAG) during a remodel

The gfci is new and is the only real change. With the light switch off, there is no current imbalance detected.

Lift the grd from the fixture cable and see if the gfci holds with the switch on and good bulb in fixture. If it doesn't trip, then there is a grd occurring somewhere between cable and fixture.

If you were to hook the switch up to the line side of the gfci, does the light work then?

Get a real voltmeter.......only way to troubleshoot.

 

[FMC1959]

Pull the light socket and disconnect the white wire. Check for continuity between the neutral connection and the ground (mounting bracket, etc). If it’s bonded or shorted (continuity) that’s why. The current going out on the hot lead must be the same as the return current on the neutral (well within a couple hundred miliamps). With it bonded the return current is split (in theory)

Rereading, how do you have the ground connected to the fixture? Also you’ll need a cheap multimeter for testing continuity.

Because I was just doing a test with the new socket, the ground was not connect to the socket, just hanging loose. If I were to install it, most sockets don't have a screw for the ground (mine is a cheap plastic basement/garage socket), I would attach the ground to the octagonal box holding the socket in place.

Not sure it matters but the ground is connected to the light switch. I have seen light switches that do not have a screw for the ground.

 

[FMC1959]

You might not be doing anything wrong, the fixture could be shot and leaking a little current to ground. Also, you don't have to GFCI protect the light, but since it is tripping it you might as well just buy a new light.

I had removed the fixture in place. This testing I was doing was with a generic cheap white plastic fixture. I took it out of the plastic bag brand new. So I don't think it was leaking to ground.

 

[FMC1959]

Since it's 1900 vintage, I'm sure it saw knob & tube, first versions of romex, etc. Possibly, someone connected a nuetral or ground wire to a pipe (SWAG) during a remodel

The gfci is new and is the only real change. With the light switch off, there is no current imbalance detected.

Lift the grd from the fixture cable and see if the gfci holds with the switch on and good bulb in fixture. If it doesn't trip, then there is a grd occurring somewhere between cable and fixture.

If you were to hook the switch up to the line side of the gfci, does the light work then?

Get a real voltmeter.......only way to troubleshoot.

Well, before I installed the GFCI, I did connect (just touched the lead) the light switch black the the line black, the light does light up. But as stated, I did not connect, only touched it for 2 seconds. My worry is shorting something if I connect it.

I have checked many (but not all) areas of the house, no knob & tube detected. There are many outlets with hot & neutral reversed. Many Outlets upside down (ground pin on the top). There many wires in the house that have the old paper covering.

This box I am working on, all the wires look relatively new.

You say to lift the ground from the fixture to see if it holds. As mentioned, the ground was not connect to the fixture, but it is connected to the switch at the other end. So I should check if it hold when I remove the ground from the switch, so no ground connect at either end?

I have a voltmeter, trouble is my knowledge on using it is very basic. I know how to check for continuity. I also know how to read voltage...but not much else.

 

[FMC1959]

"Check for continuity between the neutral connection and the ground (mounting bracket, etc). If it’s bonded or shorted (continuity) that’s why. The current going out on the hot lead must be the same as the return current on the neutral (well within a couple hundred miliamps). With it bonded the return current is split (in theory)"

I will check the neutral as stated, and also try removing the GROUND (edited, I had neutral before) at both ends of the fixture and light switch...but will do these tomorrow (and report back) as it is too late for me to work in this tonight.

 

[Joemctag]

Well, before I installed the GFCI, I did connect (just touched the lead) the light switch black the the line black, the light does light up. But as stated, I did not connect, only touched it for 2 seconds. My worry is shorting something if I connect it.

I have checked many (but not all) areas of the house, no knob & tube detected. There are many outlets with hot & neutral reversed. Many Outlets upside down (ground pin on the top). There many wires in the house that have the old paper covering.

This box I am working on, all the wires look relatively new.

You say to lift the ground from the fixture to see if it holds. As mentioned, the ground was not connect to the fixture, but it is connected to the switch at the other end. So I should check if it hold when I remove the ground from the switch, so no ground connect at either end?

I have a voltmeter, trouble is my knowledge on using it is very basic. I know how to check for continuity. I also know how to read voltage...but not much else.

Here in the U.S. ground pin up or down are both allowed.

 

[FMC1959]

Here in the U.S. ground pin up or down are both allowed.

Yes, in Canada also, but pin up looks awkward. Back in the 60's or 70's it wasn't as big deal, but today, many electrical devices, power bars and some extensions, have the wire take a 90 degree turn right from the plug. So for these items the wire goes up and then curves back down because your outlet is upside down. I am sure there are other reasons the ground pin on the bottom makes more sense, me, it bothers me to have it on the top when I ma so used to it almost always on the bottom.

Another reason it bugs me is because this house has half of the outlets up, and half down. I had also found 2 light switches that on was the down position.

This house has 1600sq ft section in the front of the house which was the village general store, post office and once a week the bank would come in a setup for the day, back in the 40's & 50's The owner back then was from all accounts the Mr Fixit of the village and did all kinds of plumbing, electrical and any other work required. Based on many things I have seen in electrical work (and plumbing), it is no small miracle that some of these houses have not burned down.

 

[dave*99]

"Check for continuity between the neutral connection and the ground (mounting bracket, etc). If it’s bonded or shorted (continuity) that’s why. The current going out on the hot lead must be the same as the return current on the neutral (well within a couple hundred miliamps). With it bonded the return current is split (in theory)"

I will check the neutral as stated, and also try removing the GROUND (edited, I had neutral before) at both ends of the fixture and light switch...but will do these tomorrow (and report back) as it is too late for me to work in this tonight.

It's important to understand the goal of this test. Focus on the Romex going from the switch box to the light fixture. We need to be sure the white wire and ground wire do not touch anywhere along their run.

If you completely disconnect that piece of Romex on both ends and test continuity from the white to ground wire, it should be open. If for instance someone drove a staple through that Romex and shorted white to ground, your GFCI can trip but it may not happen until a bulb is drawing current.

 

[FMC1959]

I think I found the problem.

Originally the light stopped working and it was due to the light switch being fried. I changed it and at the same time introduced the GFCI. What I did not see (yes, I am the problem) was that the 2 neutral whites, 1 from line and 1 for the light switch were pigtailed together (I thought I saw the load white and light switch white pigtailed). Connect this the the line side of the GFCI was fine for the outlet. I connect the load white and black to the appropriate GFCI load connection.

So, if I understand this correct, the GFCI would pop every time I tried to turn on the light switch because the black was connected to load and the white to line, not completing the circuit that the GFCI verifies.

Does this sound right?

Another question as I finish up on this. I have to see what fixture I will use, but if it is a fixture that has no special ground connection, then just connect the ground to the metal box holding the fixture is fine?

Thanks to everyone for their help

 

[FMC1959]

It's important to understand the goal of this test. Focus on the Romex going from the switch box to the light fixture. We need to be sure the white wire and ground wire do not touch anywhere along their run.

If you completely disconnect that piece of Romex on both ends and test continuity from the white to ground wire, it should be open. If for instance someone drove a staple through that Romex and shorted white to ground, your GFCI can trip but it may not happen until a bulb is drawing current.

I did a test earlier, which was a useless test I believe. When everything was disconnect, I checked the white that would go to the light switch and at the other end to the fixture for continuity...again, useless test. It showed the white intact.

I forgot to check the white and ground to see if there was any continuity, when they were all disconnected. Now that I have everything connected and working, if a staple or nail had shorted the white and ground, the GFCI would definitely alert me...or should I disconnect everything and check to be sure?

Then, if I re-use the old fixture, if it suffered any damage due the water (like Sparky1971 mentioned 'leaking current to ground"), again, the GFCI would detect this? (I can toss the fixture but it is a pot light that matches 7 others in the kitchen)

 

[FMC1959]

Yes, if you read all the posts on this thread, you can see I am no electrician. As the saying goes, I know just enough to get myself in trouble.

Thanks all

 

[dave*99]

Check the old fixture visually and check for continuity between white and the fixture housing or anything metallic.

 

[FMC1959]

Check the old fixture visually and check for continuity between white and the fixture housing or anything metallic.

Got it, thanks

 

[sparky 1971]

So, if I understand this correct, the GFCI would pop every time I tried to turn on the light switch because the black was connected to load and the white to line, not completing the circuit that the GFCI verifies.

If the line and load are mixed up, the GFCI is going to see it as an imbalance and trip. It doesn't know what the problem is, just that something isn't right.

Does this sound right?

Another question as I finish up on this. I have to see what fixture I will use, but if it is a fixture that has no special ground connection, then just connect the ground to the metal box holding the fixture is fine?

Most modern fixtures outside of plastic and porcelain keyless types are going to have a ground wire, but yes, bond the box.

Thanks to everyone for their help

 

[Joemctag]

Here in the U.S. ground pin up or down are both allowed.

I should have added that I’ve only seen professional commercial and residential projects done with the ground pin DOWN. At least where I’ve lived, it’s a “convention”, you can say. And it’s how I do them myself. “Looks” wrong otherwise.

 

[Chuckster in NJ]

Since it's 1900 vintage, I'm sure it saw knob & tube, first versions of romex, etc. Possibly, someone connected a nuetral or ground wire to a pipe (SWAG) during a remodel

The gfci is new and is the only real change. With the light switch off, there is no current imbalance detected.

Lift the grd from the fixture cable and see if the gfci holds with the switch on and good bulb in fixture. If it doesn't trip, then there is a grd occurring somewhere between cable and fixture.

If you were to hook the switch up to the line side of the gfci, does the light work then?

Get a real voltmeter.......only way to troubleshoot.

With 'Knob and Tube' anything is possible.……. I remember back in the early 1970’s going into a dirt floor basement and pulling out a male end of an extension cord (that was wrapped around an sewer pipe) out of a porcelain lamp holder with a receptacle and the entire basement went dark. I said WTF and checked the receptacle on the lamp holder and it had no voltage, THEN I checked the male plug on the extension cord a it had 120 volts.
A friend of mine owned the early 1900 era house and when I started looking into things I found water pipes with wires going to them or a neutral wire because somewhere a neutral was lost.……. So to make a long story short we rewired the entire house and cut out all the exposed knob and tube.

 

[KenC]

I should have added that I’ve only seen professional commercial and residential projects done with the ground pin DOWN. At least where I’ve lived, it’s a “convention”, you can say. And it’s how I do them myself. “Looks” wrong otherwise.

Commercial and residential are installed down usually, just by convention. But, every hospital, clinic and urgent care I've been in have them up. Something about objects that fall hit the ground, not a live wire.