Figuring a way ahead after finding faulty wiring

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JHZR2

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Location
New Jersey
Occupation
Power Systems Engineer
I know there are lots of these stories on the web, because I searched first before posti this one... Looking for recommendations on the way ahead.

Was as working in a home that is entirely wired with cloth type two conductor NM cable. It has an updated 100A service with 15A GE breakers, all looks good. Owners desired to install a three-prong outlet in each room, so the first step was to check the wiring upstairs. Essentially, two conductor NM comes up to an outlet, the continues on via that outlet and a junction box in the attic to feed a bunch more outlets as well as a few lighting fixtures. So the fix was to put in a GFCI at that first point, the from the load side everything would be protected, so the install a three prong duplex receptilce in each of the other bedrooms, properly labeled, so they had their convenience and protection. Easy, it worked, left.

Got a call back tonight because when they turned on the upstairs hallway light, the GFCI tripped and it went dark. So it turns out on the load side of the GFCI I installed, there are two, three way switch circuits that operate a light in one and an outlet on the other.

Testing things, switching EITHER of the three way circuits, i.e. The one that operates the light or the one that operates the outlet, trips the GFCI.

i took the box apart and saw this...

CC75951B-D14B-4F17-9143-12BA1DDFA9AD_zps7jjdqdax.jpg


AE11A114-B98D-43BE-91B9-3066983312BB_zpsxlhhqnme.jpg


scary.... Two three way switches with a bunch of wires twisted (but not nutted) together, just taped and twisted up in there. I think eight conductors total.

So what's the best way ahead? Old house, not everything is accessible from the attic or basement, and who knows why people did what they did long ago. I don't like that twisted pair that isn't even nutted...

My gut feel is that some circuit, maybe the switched outlet, is fed from another source as well, and has a crossed neutral. I suppose I could have crossed neutrals on the GFCI too, though not sure why that would cause an issue with only the three way switch operations...

So so what's the best way ahead? It seems that the easiest and least time consuming, if the issue isn't immediately obvious, would be to go back to the original GFCI outlet that I installed, jumper the load to the line screws, and then just install gfcis at all positions downstream where a three prong outlet is desired. That way each three prong op ungrounded outlet will be protected by its own GFCI.

Are re there any other approaches I should consider? I will try to look for obvious points where a neutral might be crossed or wrong, and not just immediately default to the plan b GFCI in all spots option...

but it anything else I should consider when trying to solve this and track it down?

thanks!
 
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Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
These pictures remind me of why I don't miss working on residential projects. Ditch digging is more fun unless it's cold, or hot, or muddy.

As you know, fixing that is going to be fun with each box opened a new adventure. A GFCI for each device would appear to be the best work around but those old boxes barely had enough room for the 2 wire device.

No real help here.
 

KundaliniZero

Member
Location
CL
Hi i am new. It the first time i heard GFCI. I recently saw how it work. I think GFCI trigger with mA in my country we don t use it.

I think GFCI is triggered because a wire is inducting current in other circuit which belong to GFCI. 5ma is too easy to trigger it happened to me with another device triggered by 30 mA

That it happened to me when i put two circuits in the same conduit, one of them it has a similar device a residual current device (RCD sensibility 30 mA) the other had ilumination.

Enviado desde mi GT-I9195 mediante Tapatalk
 

JHZR2

Member
Location
New Jersey
Occupation
Power Systems Engineer
Forgot to mention, generally, I find the neutral to be switched instead of the hot in old wiring such as that.

That was going to be a first check. There is a "modern" NM-B wired outlet in the bath with a functioning ground. So I was going to check potential first to see which conductors show me 120v.
 

JHZR2

Member
Location
New Jersey
Occupation
Power Systems Engineer
These pictures remind me of why I don't miss working on residential projects. Ditch digging is more fun unless it's cold, or hot, or muddy.

As you know, fixing that is going to be fun with each box opened a new adventure. A GFCI for each device would appear to be the best work around but those old boxes barely had enough room for the 2 wire device.

No real help here.

The box I put the GFCI in was just big enough. My concern is that I'm not sure there is enough space to put a nice jumper in to allow me to put both conductors on the line side. Because of the age and condition of the wires, I'm somewhat concerned on that one. The other outlets all just have one set of wires coming in, so no big deal.
 

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
Hi i am new. It the first time i heard GFCI. I recently saw how it work. I think GFCI trigger with mA in my country we don t use it.

I think GFCI is triggered because a wire is inducting current in other circuit which belong to GFCI. 5ma is too easy to trigger it happened to me with another device triggered by 30 mA

That it happened to me when i put two circuits in the same conduit, one of them it has a similar device a residual current device (RCD sensibility 30 mA) the other had ilumination.

Enviado desde mi GT-I9195 mediante Tapatalk
More likely capacitance than induction. Capacitance allows current to flow outside the wired path. Induction can cause unbalanced voltages but current flow in the closed loop will still balance.
Now inductive kick from opening a switch can cause high induced voltage spike in another circuit and that spike can cause larger current through stray capacitance.
 

growler

Senior Member
Location
Atlanta,GA
My gut feel is that some circuit, maybe the switched outlet, is fed from another source as well, and has a crossed neutral.

Are re there any other approaches I should consider? I will try to look for obvious points where a neutral might be crossed or wrong, and not just immediately default to the plan b GFCI in all spots option...

There is the possibility that the neutrals are crossed but it's also possible that you have a ground fault when the light switch is turned on.


Just because the system is ungrounded doesn't mean there are no grounds in the house. I'll bet there are old metal water pipes in that house.
 

JHZR2

Member
Location
New Jersey
Occupation
Power Systems Engineer
There is the possibility that the neutrals are crossed but it's also possible that you have a ground fault when the light switch is turned on.


Just because the system is ungrounded doesn't mean there are no grounds in the house. I'll bet there are old metal water pipes in that house.

Agreed, but given where the light is and the wires are run, it is indeed ungrounded. And it would also assume that there is some leakage of current elsewhere, which is not definitely the case.

not arguing or saying you're wrong, but from observing the run, I'm not seeing how it would be grounded to anything...
 

growler

Senior Member
Location
Atlanta,GA
There is the possibility that the neutrals are crossed but it's also possible that you have a ground fault when the light switch is turned on.

Agreed, but given where the light is and the wires are run, it is indeed ungrounded. And it would also assume that there is some leakage of current elsewhere, which is not definitely the case.

not arguing or saying you're wrong, but from observing the run, I'm not seeing how it would be grounded to anything...

I'm not saying I'm right only a possibility ​of a ground fault that would not be enought to trip a breaker or show up normally. Things that can be checked without opening other boxes and only take a couple of mintues.

A lot of old paster is done with chicken wire and that can ground a metal box to and old metal drain pipe.

The light would not have to be grounded, it could be at any point past the switch to include the switch junction box.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Here is the kind of things you may find hiding on a job like the OP describes.

This was in a cupboard. Yep, that's a shelf built over the box. A cover can just be squeezed on.

View attachment 13469

This was hiding in a decorative ceiling beam. I think that's what it's called. We had to remove the bottom to get to the wiring. You are looking from the bottom up. Click on the pic to get a better view. What you see was covered in layers of hard, old, nasty friction tape and was intermittently stopping power to about half the cottage.

View attachment 13470

I'm glad I never have to bid on jobs that have wiring like this. Some guys do and I've seen them lose their shirts bad on some of them. You never know what's hiding in these funky old places.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
A lot of old plaster is done with chicken wire and that can ground a metal box to and old metal drain pipe.

I had a job once that had 2-wire in a garage, no grounds anywhere. The owner had put 3 hole receptacles in and they all checked out OK with my ice cube tester. The garage had a sub-panel in it, no EGC there, no 3 wire cable.

I tore my hair out trying to figure out where the 'ground' was coming from......then I discovered the wire mesh in the plaster. The boxes were metal, touching the mesh. The sub panel was screwed into the plaster and thus, the mesh as well. The neutral bar in the panel was not insulated.

So, yes....it can....and does happen.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
And when you think you have seen everything. Surprise there is a new one.

I don't have a pic but a while back I saw a job the inspector not only tagged, but had the POCO pull the meter until a service upgrade was done. I kept the old disco and have part of the triplex with a hole.

It went something like this:

POCO fed #6 triplex with holes burned part way through from (I think) lightning. Only one leg used, the other taped off and folded back on itself. #6 noodle to meter. This is now 120 volts, remember. #10 from meter socket feeding ancient disconnect with both hot and neutral fused not once, but twice. There were 4 30 amp fuses for the single circuit. Two inside the disco, and two outside on the bottom. Inspection sticker from 1919. #4 split into two circuits at ancient panel feeding new 100 amp Sq. D. Homeline breaker panel. 120 volts to ground, 0 volts from leg to leg. No 240 volt on the premises.

This was a two story approx. 1300 square foot home in the city. There were A/C units in the windows! Everything was working fine since 1919. The inspector shut it down when it turned to a rental and had to be inspected.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I was a first year apprentice when we put a service on a small home. POCO told the owners no more power unless a fuse or CB was installed. Only fusing was on the POCO primary of a 50 KVA transformer. One Romex down the center of the attic split on occasion to allow the 16 gauge zip cords to wrap around a conductor. Even back then it was a :jawdrop:for me.
 

JHZR2

Member
Location
New Jersey
Occupation
Power Systems Engineer
I'm not saying I'm right only a possibility ​of a ground fault that would not be enought to trip a breaker or show up normally. Things that can be checked without opening other boxes and only take a couple of mintues.

A lot of old paster is done with chicken wire and that can ground a metal box to and old metal drain pipe.

The light would not have to be grounded, it could be at any point past the switch to include the switch junction box.

Agreed. Found that in my own home on a light that was mounted to the aluminum siding...

cheers!
 
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