Tips for troubleshooting older homes??

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milemaker13

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Suburbs of Chicago
Hey Gang!
I've recently come across several older homes that all had the same problem (one of those being my own home, lol) . A loose neutral connection of some kind..

What I'm seeing is a room or two goes dark (one circuit). I get 120v from hot to ground, 100v from neutral to ground, 0v between hot and neutral. Gets even weirder when you throw in a light switch. 90v/30v split and such...

Most of the time I get fairly lucky and locate a box with a loose neutral connection, or a melted outlet... one was a plug connector for an old 110v smoke alarm.

Some times I hunt around for hours opening a dozen boxes all over the house.


Can anyone clue me in a little bit... Lol, any tips to finding the offending box or connection.

What can be done to prevent or protect against this kind of fault? A slipped neutral.. No breakers in any of these recent jobs have been tripped.

Most of my work is in industrial building where you can follow the conduit around with your eyes.. So it takes me some time to imagine how they piped it when it was being built. Any tips there?
 
milemaker13 said:
Hey Gang!
I've recently come across several older homes that all had the same problem (one of those being my own home, lol) . A loose neutral connection of some kind..

What I'm seeing is a room or two goes dark (one circuit). I get 120v from hot to ground, 100v from neutral to ground, 0v between hot and neutral. Gets even weirder when you throw in a light switch. 90v/30v split and such...

Most of the time I get fairly lucky and locate a box with a loose neutral connection, or a melted outlet... one was a plug connector for an old 110v smoke alarm.

Some times I hunt around for hours opening a dozen boxes all over the house.


Can anyone clue me in a little bit... Lol, any tips to finding the offending box or connection.

What can be done to prevent or protect against this kind of fault? A slipped neutral.. No breakers in any of these recent jobs have been tripped.

Most of my work is in industrial building where you can follow the conduit around with your eyes.. So it takes me some time to imagine how they piped it when it was being built. Any tips there?
Click to expand...
Well if wiring is concealed it is not so simple to know just exactly what route is taken, though there may be some clues. One thing that seems easy to overlook is that the bad connection may very well be at the last working outlet in the circuit, just because it is working people tend to disregard it as having the problem but if incoming line is good and outgoing line is bad you will never know until you open it up and see it.

There are tracing tools out there that may be of some help, but some may not be justified in their expense if you seldom need to use them or have no other situations where you ever use them.
 
kwired said:
Well if wiring is concealed it is not so simple to know just exactly what route is taken, though there may be some clues. One thing that seems easy to overlook is that the bad connection may very well be at the last working outlet in the circuit, just because it is working people tend to disregard it as having the problem but if incoming line is good and outgoing line is bad you will never know until you open it up and see it.
Click to expand...
Last troubleshoot I had the problem was in a working outlet.
How did I find it? A trick my Dad taught me. banged on the outlet and wall with my fist. Stuff came on that was off so I knew I was in the right place.
 
One of the things about troubleshooting old houses is who came up with the idea of feeding a circuit from the light? What a pain to have to take down light fixtures to locate a loose neutral that is crammed with a butt load of wire above a light with a 100+ watts of light. Closet pull chains have been the most fun cause you hardly ever think they are there.
 
qcroanoke said:
Last troubleshoot I had the problem was in a working outlet.
How did I find it? A trick my Dad taught me. banged on the outlet and wall with my fist. Stuff came on that was off so I knew I was in the right place.
Click to expand...

Another good way is to use a plug tester. Go to the last working receptacle and plug in your tester. Then "wiggle" the tester to see if the other receps start working.

If the recep is only a 2-prong one you can use a breaker finder (the part that plugs in) because they have only 2 prongs, and wiggle it. But you could just use anything with a hefty plug to plug in and wiggle.

It helps to plug in a radio into one of the non-working outlets so you can hear if you find where the break is.

I found you need to make sure the radio is not the type that has to be turned back on after a power failure. Else you will never know if you find the culprit!:slaphead:
 
Ok I'm at home now. I have an outlet with 125v across hot and neutral. 85 volts from hot to ground. 40 volts from neutral to ground.
Another place I have a switch. I have isolated the wires, and they seen fine. No bleeding to ground or between conductors. When i put 125v on one conductor, 20 volts sites up on the second conductor. This is old cloth covered romex type cable. Turning the switch on, i get 125v back out.
 
milemaker13 said:
Ok I'm at home now. I have an outlet with 125v across hot and neutral. 85 volts from hot to ground. 40 volts from neutral to ground.
Another place I have a switch. I have isolated the wires, and they seen fine. No bleeding to ground or between conductors. When i put 125v on one conductor, 20 volts sites up on the second conductor. This is old cloth covered romex type cable. Turning the switch on, i get 125v back out.
Click to expand...

Sounds to me that the ground wire you are measuring to probably is not really connected since your talking of an older home. And if you are using a digital volt meter don't be misled by its readings because of induced voltage across wires that run together which will is not a problem we sometimes call this phantom voltage, the digital meter has to high resistive value to give good readings when it comes to troubleshooting. Grab a good old wiggy meter and check.
 
I don't think there are too many tricks. Take apart your last working on your suspect circuit and ohm to the next recep in line. Check hots and neutrals, if one is missing...........there you go.

Sometimes you get cases where things aren't wired very cleanly and it's hard to imagine how they may have done it.

Mostly it's just common sense and experience.

And yeah, the old power the light box was never a good idea.
 
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mopowr steve said:
Sounds to me that the ground wire you are measuring to probably is not really connected since your talking of an older home. And if you are using a digital volt meter don't be misled by its readings because of induced voltage across wires that run together which will is not a problem we sometimes call this phantom voltage, the digital meter has to high resistive value to give good readings when it comes to troubleshooting. Grab a good old wiggy meter and check.
Click to expand...


+ 1.

"Usually" any low number like that on a ohm meter is a false reading. Lighted switches give off a voltage reading when they are off as well.

If you put a load on your low voltage reading it would disappear.
 
milemaker13 said:
Ok I'm at home now. I have an outlet with 125v across hot and neutral. 85 volts from hot to ground. 40 volts from neutral to ground.
Another place I have a switch. I have isolated the wires, and they seen fine. No bleeding to ground or between conductors. When i put 125v on one conductor, 20 volts sites up on the second conductor. This is old cloth covered romex type cable. Turning the switch on, i get 125v back out.
Click to expand...

What are you checking the hot/line to at the switch? Meaning most likely there isn't a neutral in the switch box since it's an older home.
I agree, most likely you have phantom voltage with the readings you have. Also sounds like you don't have the ground/egc bonded at the panel.
 
All good information so far. Connect an extension cord to a receptacle that you know is wired correctly. Now you can use the female end of the extension cord to verify wiring at problem receptacle.
 
mopowr steve said:
And if you are using a digital volt meter don't be misled by its readings because of induced voltage across wires that run together which will is not a problem we sometimes call this phantom voltage, the digital meter has to high resistive value to give good readings when it comes to troubleshooting. Grab a good old wiggy meter and check.
Click to expand...

Interesting. I have been using a digital meter this whole time. This could very well be happening here.
 
I was up all night going thru fixtures and boxes. Just improving the poor connections, crumbling insulation, that kind of thing looking for a problem. I found a lot of really crazy looking rat nests of soldered wires... but no obvious fault, and no improvement in the condition. But I did gain a better understanding of what I am looking at here.

All my connections seem OK. Using the extension cord idea from above (great minds think alike!) I have determined that I have 125v on my hot side and 0v on my neutral side. But I also don't have a ground connection to the main panel. All these devices and boxes are grounded together (bonded?), but they are not grounded the same as a known good outlet.

From the known good extension cord ground, to the ground on my troubled outlets my digital meter shows 50 v.

Another example: Under my cabinet I have two different outlet boxes, close enough to touch both with my meter probes... One is the old stuff, one is a newer direct line. I show 50v between the two steel boxes.

Could this just be phantom voltage that would disappear if I bonded these two boxes together?
 
OK, we seem to be heading in the right direction:) I ran a jumper wire between these two steel boxes, and now the first "bad" out let is "good". 125 hot to ground, 0 neutral to ground. Awesome.

But apparently all these devices aren't as well bonded as I thought, lol. Of course they aren't ! So other outlets downstream still have the funky condition.

So now its a matter of logistics I guess... Most practical way to bring a ground wire over to those other outlets:blink:

I want to thank everyone that helped. I feel like I have a few extra tools in my belt now when it comes to tackling these older homes. The phantom voltage / digital meter tip is a gift! Without the idea that the digi was inaccurate, why would you second guess the reading? Wow.
 
Rather than saying that the digital meter is inaccurate, I would rather say that it was measuring very accurately a voltage that you are not particularly interested in.
Also, for receptacles anyway, installing GFCI devices can make the system much safer without the major hassle of getting an EGC to each outlet.
But a plug in tester will still show a missing ground. :)

Tapatalk!
 
Its the plug in tester that I'm afraid of:eek: My final inspection on this repair odyssey is Monday. I just know if I don't fix this, he'll pull out the plug in tester and fail it.

Better to be ready and him not give it a second glance, right?
 
milemaker13 said:
Its the plug in tester that I'm afraid of:eek: My final inspection on this repair odyssey is Monday. I just know if I don't fix this, he'll pull out the plug in tester and fail it.

Better to be ready and him not give it a second glance, right?
Click to expand...


Inspection???

I thought you were doing this in your own home.

Anyway is it a home inspector or an electrical inspector.

An electrical inspector will understand the "no ground" problem but you must make sure:
1)- you don't have 3-prong receptacles with only two wires
2)- if there is only two wires you need to change the receptacle to a 2-prong (no ground)
or
3)- replace the receptacle with a GFCI receptacle and put the little stickers on that say "no equipment ground"
or
4)- run either a new home run or find a good ground/EGC and tap into that. It's usually easier to just run a new home run.
or
5)- replace the breaker for the circuit with a GFCI breaker, but you still need to label each receptacle as "no equipment ground"

If it's just a home inspector explain to him what you did to remedy the problem. If you installed GFCI protection and he still says no ground. Tell him to go pound sand!!!:happyyes:
 
milemaker13 said:
Interesting. I have been using a digital meter this whole time. This could very well be happening here.
Click to expand...

To get a little deeper into what is happening here it is not so much from induction but rather what they call capacitive coupling.

Remember a capacitor is two conductive components with an insulating component between them. Now think of what you have in raceways and cables - the same thing. Get a cable with one "live" conductor in it next to a couple other conductors that are insulated from the first one and you will charge this rather crude and fairly weak capacitor, but it is still a capacitor. When you connect a high impedance meter across the "capacitor" you read the stored voltage in said capacitor. If you connect a low impedance meter across the capacitor - it is such a weak capacitor the low impedance off the meter completely discharges what was stored in it. That capacitance is so weak that just putting your fingers across it will discharge it without you feeling a thing - but is not a good suggestion to do so just in case it is not capacitive coupling that is driving the reading you see.

There are digital meters that have a low impedance or a low impedance setting, voltage/continuity testers, soleniod type testers, and most analog meters are low impedance and will not read voltage when this coupling is taking place.
 
All fixed now. I ran 3 bonding jumpers. One to each offending outlet. Now i get proper readings on my digital meter. Again, thanks to you all. I have a better understanding of this type of fault now.
 
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