Open ground or neutral in branch circuit? 120v L to N, ~80v L to G, ~40v N to G

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turbozoin

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I took a look at a friends house today just to give a thumbs up or down on his electrical system. Cutler Hammer panels, decent work, and most circuits are sound. However, one branch circuit feeding a couple duplex receptacles and lighting for two rooms, has an issue. My basic 3 light plug tester showed reverse polarity on the receptacles. I checked wiring in the boxes and the wires were landed accordingly, whites to proper side of recep and blacks to proper side of recep. I believe L and N were crossed up in a box upstream because I read voltage on the white wire with my NCVT and nothing on the black wire. I swapped them on the recep and then saw my 3 light plug tester read "Okay". Although, the middle light was bright and the second yellow light was dimly light. It was borderline and "open ground" reading. THEN, out came the fluke meter. Keep in mind, in this situation "L" is the white wire and "N" is the black wire in the box(terrible, I know...). 120v "L" to "N", 80v L to G, and 40v N to G. I have seen a similar issue before when a ground wasn't tied through upstream in a branch circuit. On that occasion, I saw an inadequate voltage from line to ground. But I don't remember seeing voltage on the neutral, it's possible I didn't test neutral to ground that previous occasion. Anyway, I will spend a little more time investigating the cause of this issue. I will find the problem. I just don't know when I'll have time to return to do so. Will the issue create a hazardous situation? Do I need to advise that my friend discontinues use of the said receptacles. Thanks to all who read my post, and good day.
 
turbozoin said:
I took a look at a friends house today just to give a thumbs up or down on his electrical system. Cutler Hammer panels, decent work, and most circuits are sound. However, one branch circuit feeding a couple duplex receptacles and lighting for two rooms, has an issue. My basic 3 light plug tester showed reverse polarity on the receptacles. I checked wiring in the boxes and the wires were landed accordingly, whites to proper side of recep and blacks to proper side of recep. I believe L and N were crossed up in a box upstream because I read voltage on the white wire with my NCVT and nothing on the black wire. I swapped them on the recep and then saw my 3 light plug tester read "Okay". Although, the middle light was bright and the second yellow light was dimly light. It was borderline and "open ground" reading. THEN, out came the fluke meter. Keep in mind, in this situation "L" is the white wire and "N" is the black wire in the box(terrible, I know...). 120v "L" to "N", 80v L to G, and 40v N to G. I have seen a similar issue before when a ground wasn't tied through upstream in a branch circuit. On that occasion, I saw an inadequate voltage from line to ground. But I don't remember seeing voltage on the neutral, it's possible I didn't test neutral to ground that previous occasion. Anyway, I will spend a little more time investigating the cause of this issue. I will find the problem. I just don't know when I'll have time to return to do so. Will the issue create a hazardous situation? Do I need to advise that my friend discontinues use of the said receptacles. Thanks to all who read my post, and good day.
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Just be careful with the fluke. They are high impedence and will read a voltage across just about anything when the voltage most likely is an inductive voltage and is meaningless.
If the circuits leave the panel correctly and the correctly marked marked wires are terminated on the devices correctly then you have you work cut out for you wring out the circuits.
 
templdl said:
... If the circuits leave the panel correctly and the correctly marked marked wires are terminated on the devices correctly then you have you work cut out for you wring out the circuits.
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About a two weeks ago I was on a job and found a circuit that had reversed polarity with the conductors on the appropriate terminals on all of the receptacles of the circuit. I looked at the panel and all circuits were leaving the panel correctly.

I found the problem in a ceiling box where someone had replaced a light with a fan and had screwed up the wiring in the box. You may want to keep that in mind as you troubleshoot this issue.
 
Can this issue create a hazardous situation? Should I advise my friend to discontinue use of the said receptacles. I would think because there is 120v from line to neutral that resistors placed on the circuit should operate normally. But seeing the voltage on the neutral concerns me. My Fluke meter didn't see any voltage from neutral to ground on other receptacles in the house. Thanks
 
turbozoin said:
Can this issue create a hazardous situation? Should I advise my friend to discontinue use of the said receptacles. I would think because there is 120v from line to neutral that resistors placed on the circuit should operate normally. But seeing the voltage on the neutral concerns me. My Fluke meter didn't see any voltage from neutral to ground on other receptacles in the house. Thanks
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Welcome to the forum..:)


You need to find the splice that is crossed and fix it so that the blacks are hots and your white wire is the neutral in all of your receptacle boxes.
 
First, you will need to completely understand the distrubution of the circuit.

It's been said here before to divide the length in half - "open", then go forward, or backward and "open".
You might get lucky or you might open everything.

If you don't find it then it's a hidden or flying slice in the wall. Not a usuall situation but not an
unlikely one either.

In your case yes, I'd tell them not to use the circuit!
 
turbozoin said:
I took a look at a friends house today just to give a thumbs up or down on his electrical system. Cutler Hammer panels, decent work, and most circuits are sound. However, one branch circuit feeding a couple duplex receptacles and lighting for two rooms, has an issue. My basic 3 light plug tester showed reverse polarity on the receptacles. I checked wiring in the boxes and the wires were landed accordingly, whites to proper side of recep and blacks to proper side of recep. I believe L and N were crossed up in a box upstream because I read voltage on the white wire with my NCVT and nothing on the black wire. I swapped them on the recep and then saw my 3 light plug tester read "Okay". Although, the middle light was bright and the second yellow light was dimly light. It was borderline and "open ground" reading. THEN, out came the fluke meter. Keep in mind, in this situation "L" is the white wire and "N" is the black wire in the box(terrible, I know...). 120v "L" to "N", 80v L to G, and 40v N to G. I have seen a similar issue before when a ground wasn't tied through upstream in a branch circuit. On that occasion, I saw an inadequate voltage from line to ground. But I don't remember seeing voltage on the neutral, it's possible I didn't test neutral to ground that previous occasion. Anyway, I will spend a little more time investigating the cause of this issue. I will find the problem. I just don't know when I'll have time to return to do so. Will the issue create a hazardous situation? Do I need to advise that my friend discontinues use of the said receptacles. Thanks to all who read my post, and good day.
Click to expand...

I run into this all the time, it typically ends up being a bad connection on the neutral in the circuit. It usually run into the those blue crimp connectors that tend to be the issue.
 
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